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What's the Difference Between Paint and Coatings?

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  • Published on Nov 26, 2022

Comments • 1 340

  • Practical Engineering
    Practical Engineering  Month ago +116

    🥑Turn dinner from a chore to a fun night in with HelloFresh: Use code PRACTICAL65 at bit.ly/3cZhkEY
    📖 My book comes out in less than a month! Preorder now for early access and other cool stuff: practical.engineering/book

    • Jan Girke
      Jan Girke Month ago

      Couldn't they just use local renewable energy for electro galvanic corrosion protection would work on ships too.
      LTO cells could last up to 50 years for that application.

    • Maps Of Being
      Maps Of Being Month ago

      one good example is the Quebec bridge, they never finished painting it for over 2 decades, had to stop a few years for environmental protections and when they restarted the project had to be done all over, and that project blocked too
      at this point the bridge is a rotting hot potato being passed between the CN and Quebec's govt

    • april generic
      april generic Month ago

      the pretreat for snow fall in minnesota is calcium chloride, it eats paint and metal like it's candy. 3 years your in a rust bucket in 7 you can see thru the body panels by year 8 you need a furnace to keep your interior warm.

    • Alivo Hereiam
      Alivo Hereiam Month ago

      Sorry but never preorder!

    • Vault Traveler
      Vault Traveler Month ago

      So you could say you are an tired chemist because of explaining?
      ...I see myself out.

  • Glenn Draper
    Glenn Draper Month ago +2434

    This retired paint chemist says thanks for explaining this in a way that people not in the industry could understand. Ever thought about getting your "rustomatic" an ASTM approval? The current tests are in sealed boxes, for reasons you have yourself discovered. Again, thanks for highlighting this little-known, but important, field. Take care.

    • Glenn Draper
      Glenn Draper 25 days ago +1

      @Larry Vaughn They were lying to you. And then when stuff like this happens everyone blames the paint and not the applicator. We get accused when writing specs like that of "just trying to sell more paint" but we write those only after thoroughly testing our product. I never wanted the paint I formulated to fail.

    • Larry Vaughn
      Larry Vaughn 26 days ago +1

      Good info. We hired a company to paint some outside metal stairs and the specs called for 3 coats. They put on one thick coat and said it was the equivalent of 3 coats. I went by a few years later and a lot of it had peeled off with lots of rust underneath.

    • Loris Rrahimi
      Loris Rrahimi Month ago +2

      Im a young paint chemist and i want to thank you for acknowledging the work thats behind high performance coatings it kinda made me happy😁

    • Master
      Master Month ago

      The mark of a truly wise individual is the ability to explain immensely complex things in a way that even a child can understand.

    • Derek Frigon
      Derek Frigon Month ago

      You know you knocked it out of the park when a paint chemist shows up to pat you on the back.
      Thanks for keeping my brain thinking, I can't get enough knowledge. 🏆

  • rpbajb
    rpbajb Month ago +1488

    I was a paint and coatings chemist for nearly 40 years. Grady nailed it in this video - no errors that I noticed. By the way, the collapsed bridge at 3:02 was the Fern Hollow Bridge in Pittsburgh, where I lived and worked. But no, I didn't paint the thing.

    • Delibro
      Delibro Month ago

      I thought about that bridge when Grady talked about the sophisticated techniques they use to protect buildings and bridges. At that bridge at contrast they not only led rust some beams to the core and even then removed those beams and let the bridge sit some more years until it collapsed.

    • rpbajb
      rpbajb Month ago

      @Obviously Ambiguous So, you have no educational credentials, no experience in the industry, and you were never taught how to have a polite discussion. Do better.

    • Obviously Ambiguous
      Obviously Ambiguous Month ago

      @rpbajb Weird, I didn't see you refute anything or back it up with "facts". 🤔 Just that you did something for some time. You sure laid your hand, but you don't even have a pair.
      Also, you can be an expert in your field, and still be conceited and prideful. That's what 'egotistical' means, if you didn't know. You're welcome for the free lesson. 😁

    • rpbajb
      rpbajb Month ago

      @Obviously Ambiguous It's not ego when you've walked the walk, and not a joke when you can back it up with facts. I've laid my cards on the table. What have you done?

    • Obviously Ambiguous
      Obviously Ambiguous Month ago

      No errors? Really? Not even at the very start when he says paint is decoration and doesn't protect a surface? 😂😂 You guys are both egotistical jokes.

  • Robert Levine
    Robert Levine Month ago +585

    Grady,
    I spent my career as a naval architect and marine engineer working for tanker operators. We had full-time corrosion engineers that monitored the ships and studied the changes in coatings.
    I remember them testing coatings in distilled water rather than salt water. It turns out that distilled water is harder on coatings than salt water. We used pure epoxy paints for potable and fresh water tanks. In general, if coatings did well in distilled water they would work well with crude oil or salt water.
    Surface preparation is everything when it comes to coating performance. In coating ships we started in most cases with a near white, SA2.5 finish. Coatings, whenever possible, were applied in a dehumidifed atmosphere. We used not only our own corrosion engineer to oversee the coatings, but inspectors from the coating manufacturers. We hired the manufacturers paint inspectors and had them report directly to us to remove pressure from the shipyard.
    As for primers we used weldable primers such as Nippe Ceramo, as well as zinc chromate and inorganic zinc, depending on location. In cargo tanks we used two coats of epoxy paint the first coat wss applied directly to the prepared surface. Coats were of contrasting colors to make seeing holidays easier.
    It should also be mentioned sharp edges are the bane of effective coating. Paint flows away from sharp corners leaving the surface exposed and a place for corrosion to start. On old bridges or ships with riveted construction there's an inherent problem of corrosion between plates of steel. When surface preparation is done you can't blast between the plates.
    Bob

    • Thomas M Leahy
      Thomas M Leahy 16 days ago

      @Charles Courtwright Yes, vinegar will work, and you'll have to flush that out with water to remove the taste/smell.

    • Josh Revelo
      Josh Revelo 24 days ago

      @FullMetal Kind of crazy these are available at most stores for a buck with no warning on the label.

    • FullMetal
      FullMetal 25 days ago

      @Josh Revelo no, it is absolutely not.
      A glass woth won't hurt you, but a bottle WILL mess with you.

    • Louis Victor
      Louis Victor 26 days ago

      @Larry Vaughn But that will come out from your overall health, diet and total water intake, and shouldn't come down to the difference between distilled water and actually safe for consumption drinking water (or any other liquids). The water you injest (be it drinking water, juice, inside your solid food) doesn't go straight to urine formation, it always enters the body proper through the digestive system, so everything else previously mentioned also applies here. Urine is basically just the side B of filtered blood (excess water and waste), it should be far too indirect to be significantly affected by the consumption of distilled water vs normal safe to drink water on it's own. If that is making a measurable difference, this is probably the symptom of a larger issue elsewhere (e.g. already malfunctioning kidney, severe nutritional deficit, some other organ is sick, your normal drinking water shouldn't be considered safe to drink actually due to too many contaminants).

    • Larry Vaughn
      Larry Vaughn 26 days ago

      @Louis Victor Less rich urine is also good to help prevent kidney stones.

  • FuchsiaCone
    FuchsiaCone Month ago +164

    This might be off topic... Our company moved to stainless steel for outdoor fasteners. The surface corrosion was a lot less offensive to our customers. However, larger enclosures still exhibited ugly surface rust. We tried 304, 316, and I think 316L. All exhibited the surface corrosion. So we visited the nice people at the Monterey Aquarium Research Institute. While this group shares the same name as the commercial aquarium, it's nothing like the aquarium (you might enjoy that little research tidbit). We found those guys used electro polishing on all of their buoy mounted instrumentation. We then tried 304 with a passivated surface, 304 with an electro-polished surface, and 304 that was first passivated then electro-polished. Turns out 304 with electro-polishing stayed beautiful under pretty extreme conditions.
    We used elevated temperature salt-fog testing to accelerate the test interval.
    Then we setup an outdoor test site on a beach near Moss Landing CA. Photos every 30-days. Test ran for, I'm not sure but I think about, 5 years. 304 with electro-polish was super good.
    This was all done like 20 years ago now. You might enjoy exploring SS options.
    BTW: We have found that coatings like paint and powder-coat that sustains enough mechanical damage (which doesn't have to be more than a small ding or scratch) will allow corrosion to creep under the coating effectively pealing off the coating. Aluminum was the substrate material. We found anodize was the most resilient. We also found not all anodizing is created equal.
    Love your videos! Keep having fun and sharing your findings!

    • Kevin Song
      Kevin Song 9 days ago +1

      Thanks for sharing ! 304 electro polished it is then

    • FuchsiaCone
      FuchsiaCone 27 days ago

      @ItzTonyPlayz_RBX Thank you. Corrected in the post above. Silly me...

    • ItzTonyPlayz_RBX
      ItzTonyPlayz_RBX Month ago +1

      Steel*

  • Daniel Brotherston
    Daniel Brotherston Month ago +375

    Painting your home is often about protection as well. Bare drywall and wood are highly permeable surfaces that aren't resistant to water and generally should be painted for protection as well as looks.
    This is doubly so for outdoor paint.

    • Sylvia Rusty FæThey
      Sylvia Rusty FæThey 26 days ago

      @Larry Vaughn What part ya didnt get?

    • SuperDeinVadda
      SuperDeinVadda 26 days ago

      @Larry Vaughn
      Best thing is to keep the weather of you wood. A proper roof with overhang helps more than any coating will do.
      Then you have to repaint frequently and repair cracks in the paint layer as soon as possible.

    • Larry Vaughn
      Larry Vaughn 26 days ago

      @Sylvia Rusty FæThey where they cudve farmed trees....?

    • Larry Vaughn
      Larry Vaughn 26 days ago

      @SuperDeinVadda So what do you suggest, since nearly every wood home is painted, unless it's redwood or cedar left natural to turn gray eventually. Homeowner associations don't allow unpainted wood.

    • Rusty
      Rusty Month ago

      THIS! As we say in the paint industry, paint's function is to "protect and beautify". Paint protects your home, too!

  • Jamsterman25
    Jamsterman25 Month ago +203

    I’m pretty sure if engineers designed a similar testing apparatus for use in the industry they would also call it the Rust-o-matic 3000 in spite of what marketing wanted to call it.

    • Scott Strehlow
      Scott Strehlow Month ago +2

      Rusty McRustface

    • XMS Alton
      XMS Alton Month ago +3

      @M. Krabs New-World-v2024-PostWW3

    • Jason Dashney
      Jason Dashney Month ago +5

      6 months later I'd come out with the Rust-o-matic 3001 and take all their money.

    • T Hoog
      T Hoog Month ago +6

      "Bob"
      or perhaps "Rusty".

    • ludde sundström
      ludde sundström Month ago +6

      Rustinator of course

  • Simon Alan Clark
    Simon Alan Clark Month ago +483

    The Forth Rail Bridge really was painted continuously for decades, until a new, longer lasting coating was introduced ~20 years ago

    • Bandana_girl
      Bandana_girl Month ago

      It also wouldn't surprise me if the new coating was able to be applied in slightly more general conditions. Being able to have a crew actively applying it for a full week probably speeds things up as compared to only having the team apply it for a couple hours during a day because it has to be in this general temperature range fo the first six hours, and midday gets too hot, but you also need some UV to help it start to cure, so you can't do it too close to sunset.

    • Sylvia Rusty FæThey
      Sylvia Rusty FæThey Month ago +1

      @jsquared1013 I wasnt callin that aspect capitalism xD I was sayin thats how they managed to help folks survive despite the capitalism methods that wud see folks starve if left unchecked.

    • jsquared1013
      jsquared1013 Month ago

      @Sylvia Rusty FæThey "pay folks to dig a ditch and pay other folks to fill it in" has absolutely nothing to do with "capitalism" and is in fact about as far away from capitalism as you can get. What you're talking about is government WASTE and corruption, brought to you by the tax-and-spend people whose "solution" to everything is always more taxes and bigger government, inevitably creating more problems than they solve.

    • Alexander Dickie
      Alexander Dickie Month ago

      Can confirm

    • Denis O'brien
      Denis O'brien Month ago +3

      I should add I remember thinking how weird it was seeing the fourth rail bridge with no "painting tent" suspended from it at some point. FWIW Grady, they forth bridges make an interesting case study, forth rail being the oldest, forth road, suffering from cables snapping inside the big cable tubes, and a new forth road to replace the latter. Bridgey mc painty face will likely outlast them both.

  • Robb Gosset
    Robb Gosset Month ago +440

    I can't remember if you've already covered this but it would be interesting to see your take on the new safe containment structure that has been built over the remains of Chernobyl. Apparently they have to have a forced dried air circulation to prevent the structure from rusting because the radiation levels are too high inside the structure to paint it manually.

    • Warhawk76
      Warhawk76 Month ago

      Would love to see you cover this

    • WorkableWax
      WorkableWax Month ago

      Doesn’t matter anymore unfortunately Russia ruined it

    • Jess H
      Jess H Month ago +1

      @Kyle Lambert But they said the forced air circulation was for rust prevention. It's not, it's for dust containment. Full stop. I'm not sure what the purpose of your comment is

    • 1224ChrisNg
      1224ChrisNg Month ago

      all the safety systems won't work if you save Russian conscripts digging trenches in the Red Forest, thankfully the only people they're hurting are themselves

    • rydplrs
      rydplrs Month ago

      @Joe Moross that still doesn’t pass the smell test. The levels inside were near zero when they built it, and 7 years later the paint/coating shouldn’t have degraded as it’s in a controlled atmosphere.
      Whoever is saying what you wrote must have struggled through jr high science class if they took it at all.

  • maritimefred
    maritimefred Month ago +135

    I’m a chief officer on an oceangoing container ship, I always tell my guys surface prep is of upmost importance. We use coroseal and 2 part epoxy, but if it’s not prepped right it won’t last long in the very unforgiving environment. I’ll definitely use this to teach my guys of this! Thank you!

    • KuntRRyBoy
      KuntRRyBoy 9 days ago +2

      Ive been in the coasting industry for many years and never thought of those ships needing painters

  • S Thomas
    S Thomas Month ago +303

    I am an aerospace engineer who has worked with coatings, epoxies and composites. And I also had a long time Summer job in a paint store and on a paint crew. I learned the lesson about surface prep from my job on the paint crew (the family had been house painters for a few generations). Even "decorative coatings" serve to protect the underlying structure. The crew that I worked with had painted houses in our home town for decades, and the duration and protection afforded by the house paint was directly related to the quality of the surface preparation (cleaning, sanding, and later a chemical bonding agent was used), as well as the quality of the paint and the number of coats. Even in the span of time I worked with them, I could see houses that had been painted cheaply and quickly by other crews having the paint deteriorate in a few years, whereas one with our quality job might last for 15-20. The protection against deterioration of the underlying structure was also evident: well painted wooden houses more than 100 years old were common, whereas houses that were left with poor coating, could start to deteriorate in a few years.

    • wally7
      wally7 25 days ago

      @Larry Vaughn If you read that report I linked the original tests were done with smooth planed western red cedar siding and on the newer test smooth planed radiata pine siding. No mention was made of pressure treated wood.
      I know many contractors like to "season" a fence for a year before painting/staining. Pressure treated wood is an odd duck though. It starts off ~50% water by weight that has to dry. I'm wondering if contractors are spraying a stain rather then paint and they had poor performance of the stain spraying right away as there would be little absorption of the stain into the wood with the wood super saturated with water when fresh. I guess another reason to wait a year is that pressure treated wood also shrinks a lot when drying, about 1/4" in width for a 1x6 picket which if painted right away would leave bare wood exposed on the rails everywhere after it shrinks and be an eyesore.
      I'll say that building fences out of pressure treated wood must make for some wavy wonky warped looking fences. Pressure treated wood warps like crazy as it dries out. If you want a nice ruler straight fence then western red cedar for all the above ground parts (rails, pickets, trim) and metal posts is the way to go but more $$$.

    • Larry Vaughn
      Larry Vaughn 26 days ago

      @wally7 How does that work with pressure treated wood and non pressure treated cedar siding? I live in the high humidity Florida and near a woods with lots of trees. Our wood houses have to have wood replaced in a few years in some areas because the wood rots out, the lower areas are usually the worse, like fascia trim boards and door jambs. Fences typically are pressure treated and left natural to dry, sometimes for a year before painting. Contractors typically just spray one coat of paint onto the exposed surfaces after the wood is installed.

    • Dave
      Dave Month ago

      Anyone have any good video references for correct surface prep for metal buildings? I've got one with heavily oxidized paint that I need to repaint, but I'm going to need to prep it first. I'm hoping it's not going to be something like 'hand-rub Scotchbrite-red all 1500 square feet, then repeat with green, then wipe down with metal prep" or something crazy like that.

    • Victor Quesada
      Victor Quesada Month ago +2

      @wally7 WHOA! TIL! Thanks for that Wally!

    • Victor Quesada
      Victor Quesada Month ago

      @Eric For ALL things DIY, check out this guy's channel! ru-clip.com/user/ProjectFarm
      In all seriousness, his methods are not necessarily scientific in terms of statistical reliability due to repeated runs, but I love his stuff. ru-clip.com/video/S4RPaoU47jo/video.html for the paint interior episode.
      Expensive paints are often longer lasting, easier to apply, hide underlayers with less coats, and easier to clean. Your goals, needs, timeline, and budget will really determine what is best for you.

  • David V. Revay
    David V. Revay Month ago +51

    Love the content Grady. If you’d be interested in chatting with a NACE / AMPP level 3 coating and corrosion expert, and a NACE Cathodic Protection Tester, I’d be overjoyed. So many people don’t realize how complex our infrastructure is. Everything that we use to build modern structures, use materials that degrade without protection. Seeing the conditions that a large chunk of our infrastructure assets are in, is very concerning. Over the next 10 plus years, mark my word, you will see more flint Michigans, more bridges and buildings collapsing, and worse. Unless something changes. Too much corruption and greed.

    • David V. Revay
      David V. Revay Month ago

      @Heavy Ink Printing excellent man! Love to hear it. I handle superyacht coating projects within the US and abroad, in addition to bridges, overpasses, water and wastewater treatment, structural steel / buildings, water towers, pipelines, above ground tanks, etc. if it involves coatings, gel coats, metals, FRP, we are on it.

    • Heavy Ink Printing
      Heavy Ink Printing Month ago +1

      I wonder if he took a coating class he explained most of the basic knowledge of SP & Coatings? if not good job on the research & explanation. And same here I'm a certified coatings inspector/ coatings engineer in the shipyard industry.

    • James Ocker
      James Ocker Month ago

      So much infrastructure is taken for granted until it fails and people wonder why

  • Ian Nicol
    Ian Nicol Month ago +82

    Before the Forth Rail Bridge was coated with a coating made for offshore rigs, they used to paint it every 6 years and it took 6 years to paint so they were always painting.

    • kcgunesq
      kcgunesq Month ago +1

      I suspect it is as much a matter of economy as anything. They could repaint in a week, but they'd have to bring in a contractor with 100 painters. Or, they can have one (or more) maintenance guy or gal who has various tasks, but the predominant one, and the one that is assigned to do when other tasks don't have priority, is to paint.

    • Fabian Laibin
      Fabian Laibin Month ago

      that's both interesting and somewhat depressing haha

  • MaddMan119 -
    MaddMan119 - Month ago +42

    As a pipeline corrosion tech, I am loving this series. It is always tough to relay the importance of surface prep or the correct coating with management that just want to do it cheap..
    For us, we call coatings for underground structures and paint for above ground.
    The CP video was awesome for a visual of 70% of my job. When we deal with hundreds of pound of anode material to protect 10-15 miles of pipeline, people have a hard time understanding how chuncks of metal and current protect metal. It is truly fascinating to see!

  • floogy
    floogy Month ago +48

    This whole series is amazing. I'm in a team of materials engineers that is focused primarily on corrosion prevention. Anybody that wants to understand why we do what we do will be sent these videos. Thank you so much!

  • Alec Golas
    Alec Golas Month ago +10

    I worked at a shipyard painting the hulls of boats during the summer of my freshman year of college, and I always wondered what the different layers of paint were. Iirc, we had to apply three layers of protective coating, and then that got sent to the more experienced guys to do the more precise aesthetic paint layer. We never did any of that calibrating paint thickness or surface roughness, the paints were well designed so any reasonable paint roller will put down a layer that fit within the painting specs.
    Plus, those power washers to strip the paint and roughen the surface were no joke. They were about the size of a golf cart. Originally they used to strip both sides of the ship at once, till one time a guy's power washer fell below the bottom of the hill and hit the other guy in the leg. Went straight through his calf muscle.
    That job motivated me to stay in school.

  • WuggleBee
    WuggleBee Month ago +4

    As a Scot, as soon as you said "Popular Myth about bridges" I instantly knew you were gonna reference the Forth Road Bridge and it's painting. It is a cracker of a bridge btw. Not worthy of tourism especially compared to the mountains and whisky, but it's fairly cool if you're into engineering.

    • RHonda-My_Honda_CB500X
      RHonda-My_Honda_CB500X Month ago

      As a Kiwi who was this time 6 years ago finishing up a solo self tour the Western Highlands (incl Islay, Jura, Mull & Skye), I heartily concur re the mountains, the scenery, and the whiskies😁I was essentially doing my own Distillery Discovery Trail and managed to visit 29 distilleries. That might seem like an impressive number, but when the well informed (like yourself) know there are over 210 distilleries 'nationwide', I had barely scratched the surface substrate of the 'uisge beatha' topic 😆But since I'm into engineering too, I also did the Cruachan Pumped Hydro scheme ("The Hollow Mountain") tour, along with some of the other pioneering hydro schemes hidden in them thar hills.😁

  • secretsquirrel
    secretsquirrel Month ago +59

    The same myth is said about the Sydney Harbour Bridge in Sydney Australia.
    I grew up believing that this was true and also feeling very frustrated for the “painters”, having to turn around and start all over again.
    I remember asking my father about it because it didn’t make sense to me that they would turn and repaint from the end that they had just finished - wouldn’t they have to walk back to the other side and start again from there?
    I remember my dad took me to the library and he and I investigated bridge coatings. I was bored quite quickly but my father was fascinated - we both then busted the myth at future opportunities 😂
    When I was younger and lived in a rented house, in a row of similar houses all with wrought iron fences, my neighbours would “paint” their fence with something called “harbour bridge” paint.
    It was per ported to be the same as the product used on the bridge . It was a grey/silver coloured paint but it had many small pieces of metal included in the paint.
    It caused the iron fence to have a textured surface and subtly sparkle in the sunlight.
    At the time, my neighbour was absolutely convinced. I didn’t have the heart to say anything ❤️🙂

    • Ciaran Gale
      Ciaran Gale Month ago

      @John Shannon I believe you probably overlooked priming the surface. about 75% of the total time, if i recall from the video correctly

    • John Shannon
      John Shannon Month ago

      @James Bowie I just did some math on this... If it takes 30,000 liters of paint for one coat, and one coat takes 5 years, and there are 2000 working hours in a year... then 10,000 working hours to paint the bridge. This means 30,000 liters/10,000 hrs is only 3 liters per hour. Even if I half the working hours, that would be only 6 liters of paint per hour. Something seems off, as this appears too low of an application rate. Did I overlook something?

    • James Bowie
      James Bowie Month ago +3

      "Sydney Harbour Bridge has an annual $20 million maintenance budget, with its exposed surfaces needing to be repainted every five years, while other parts of the structure last 30 years without a new coat. ... It would take about 30,000 litres of the traditional 'Sydney Harbour Bridge Grey' paint to do just one coat. The paint is a registered trademark colour and not for sale on the open market." Daily Telegraph -- January 3, 2015.

    • cr01
      cr01 Month ago +1

      That paint you describe on the fence was probably a MIO (micaceous iron oxide) paint. The tiny flakes of mica lay flat and form a barrier to the penetration of moisture, and give the sparkly appearance.

    • Terry
      Terry Month ago +2

      The harbour bridge is painted with micaceous iron oxide (MIO). I believe it is Dulux Ferreko No. 6

  • Mike Fochtman
    Mike Fochtman Month ago +5

    "The Mighty Mac", the Mackinac bridge connecting lower and upper peninsulas of Michigan is one of those structures that has nearly continuous maintenance. Of course in the dead of winter, with freezing and blowing winds, it's not 'year round'. The inside/outside of towers, the cables, the deck steel, and approaches all need periodic work. At 5 miles (8 km) in length, it keeps a work crew busy. Fortunately, no saltwater though. :)

  • Michael Y
    Michael Y Month ago +7

    I really enjoyed the video since this is what I do and teach every day. Some comments on what is discussed in the video:
    1. Coating failure figures are close, but also should include application as well
    2. Testing method you are using is called a prohesion test where it's dry/wet cycling. This is definitely good and the industry uses salt fog chambers for ASTM and ISO testing. Also to get more accurate and repeatable results we do a scribe in the middle (bare steel cut) and measure the rust creepage from the scribe. For inorganic zincs, it's typically half of a regular epoxy system since cathodic passivation helps the test results.
    3. Replica tape is what the industry standard is. We use a point detector and now also use 3D mapping on the profile as well. Ultra high pressure washing is also becoming readily used for maintenance as well than just abrasive blasting.
    4. Holiday/spark testing is to detect pinholes but also for low-thickness areas of coating since we set it at a certain voltage. Typically 100 volts per 1 mil of coating. DC testing for coatings and AC spark testing for very thick and reinforced membranes/thermosets/plastics.
    5. Coating people come from all walks of life which is great with the diversity it brings. AMPP/NACE is a great organization for resources and standards that I've updated and help created over the years.

  • James Salsman
    James Salsman Month ago +19

    I used to work in the patents department of Morton International back in the early 90s where I learned more about coatings than seemed possible, and had to explain summary claims at Chicago area consolates in person to attest applications in front of clerks that had no idea of the subject. A handful of countries required that someone show up in person to recite claims and potentially answer questions before a patent application could be filed from another country. Of course it was just a weird formality from a long-ago era, and I'm sure it's gone by the wayside by now.

  • Adam Madison
    Adam Madison Month ago +8

    I am an inspector for a civil engineering company in Alabama, and I recently got involved with inspecting Water Tanks during the sandblasting and coating phase. The Tnemec product data sheet that you showed was the EXACT type that the Contractor used in my job! I always learn something new from each episode you put out. Loved this video and always watch your content!

  • Erik Swiger
    Erik Swiger Month ago +4

    This makes me think of stripping and waxing floors, and also, using epoxy resins. In both cases, preparation is what takes all the time, and determines the quality of the results.

  • 💧DRIP💧
    💧DRIP💧 Month ago +11

    Grady you’re one of the best teachers that I’ve ever had the pleasure of learning from. Thank you so much for making your videos so accessible and so interesting and informative. This video, along with the first two taught me so much about corrosion. You’ve taught me about weirs, culverts, potholes, flood gates, and that’s just off the top of my head. I really appreciate you!

  • Dillon Bothwell
    Dillon Bothwell Month ago +6

    I do blade repairs on wind turbines and had a conference call with engineering trying to figure out if we needed to feather out our paint on a 1 foot external repair. I had a rough idea of why we used 3 layers of different coats but this fully explains it.

  • Special EDy
    Special EDy Month ago +13

    I recently refinished a very old pistol that had a rough duty life. Stripped it down to polished, bare steel. Then, coated it in corrosive chemicals that flashed rust all over it, then dipped it in boiling water to convert the iron oxide into black oxide. Had to repeat the process about 10 times to get a beautiful, dark coat of bluing.
    Chemistry is always baffling and truly amazing. I'm an Industrial Mechanic(mostly robotics), I fancy myself as a fairly competent mechatronic engineer as a hobbyist, but if there was one subject I wish I was smart enough to study and become an expert on, it'd be chemistry. You chemists are the real heros.

  • Dean Collins
    Dean Collins Month ago +4

    The one thing I noticed was that you appeared to use the same brush for applying the coating to the 4 test specimens, starting with one of the oily specimens. I would have recommended different brushes for each specimen to prevent cross contamination.

  • Adam Carmichael
    Adam Carmichael Month ago +4

    One of the neighbouring companies at work specialises in corrosion control, I'm kinda interested in knocking on their door now and asking if they haveay have a few minutes to show me around what they do. Thanks Grady!

  • Clay Suddreth
    Clay Suddreth Month ago +3

    my first serious job was selling paint and coatings. This was mostly to homeowners and organizations doing their own maintenance. Client education was a huge part of the process, at least for those that were willing to listen. I always said as a rule of thumb that you should spend more time on prep than on actually applying the paint. This isn’t always the case, but considering the number of people I saw that were wanting to apply paint with literally zero cleaning, zero sanding, zero prep of any kind, I felt that exaggeration was necessary to make a point.

  • Richard Vickers
    Richard Vickers Month ago +16

    You're right, Grady, you can make watching coatings perform interesting. My favorite tech channel btw.

  • ryanjamesj44
    ryanjamesj44 Month ago +6

    Can you do a series on preventing wood rot? I deal with this all the time and had a big impact in construction.

    • jim b
      jim b Month ago

      fastest wood rot is where soil touches wood in the top six inches of the soil, where oxygen and water is readily available. otherwise in the cracks between and under wood pieces, where wood stays moist. moistness always fosters mold growth and encourages termite and other boring insect colonies. water seems to always work its way through any coating because of the soft surface causing cracking and the wood stays moist under the coating layer. old timers have sworn to me that if you can build so that the wood dries rapidly everywhere after a rain, an uncoated piece of wood will last forever, the biggest enemy being wind driven sand or snow erosion and wasps/hornets chewing off the surface to build nests (but thats a big problem only after 200-300 years).

  • Manuel Camera
    Manuel Camera Month ago +5

    i'm a complete stranger to the engineering world, thanks to this man i'm discovering a whole new universe

  • Alan J
    Alan J Month ago +9

    I was brought up

  • Alexander Thomas
    Alexander Thomas Month ago +4

    We have a balcony with iron railings, and re-painting them is always a chore, because indeed at least 80% of the total time for the job goes into preparing the surface. After a few years, the spots we hadn't properly sanded and de-greased will mercilessly become visible.

    • lajya01
      lajya01 Month ago

      I got rid of mine last summer for that reason. I liked the style but it's too much of a hassle to maintain. I've replaced it with wood railings with aluminum bars.

  • Jon
    Jon Month ago +6

    Wonderful series! Really well explained.
    I would love to see more about coating types and their fillers.
    One of the coolest I have heard of, is the glassflake filled costings used on oilrigs. These can last for decades as the flakes both gives an inert and impact resistant surface, but most importantly increases the distance water has to travel through the coating without increased to thickness.

  • Rockscanfly
    Rockscanfly Month ago +12

    It's definitely an ongoing area of research. One of the Academics at my uni has made her career in non-destructive defect detection and she currently has a PhD student investigating methods of rust detection through anti-corrosion coatings

    • Robert Levine
      Robert Levine Month ago +1

      As I recall the American Bureau of Shipping (ABS) had been doing work with strain gauges placed on painted and unpainted surfaces to study detection of structural fatigue cracking. At one point prior to my retirement in 2009, I discussed the possibility of placing strain gauges in cargo and ballast tanks on our tankers.
      ABS would be a good starting point to look at coatings and structural cracks. Another source is the Tanker Structural Cooperative Forum (TSCF). The TSCF is made up of Oil Company's marine operators, independent tanker companies and marine classification societies. TSCF has publications on design, inspection and coatings.
      I find it interesting how so many of the issues that I encountered with tankers so closely parallel those ashore. Infrastructure issues are very much the same. Currently there is information coming to light on potable water contamination by JP5 jet fuel on the aircraft carrier USS Nimitz. Information to date makes it seem like a Flint, Michigan issue.
      Bob

  • unfa🇺🇦
    unfa🇺🇦 Month ago +14

    This was fascinating. It seems like coating large steel structures is really hard work, not just because of the amount of labor required, but also the tight specifications on what will work well and what will fail prematurely. Respect to everyone doing this job!

  • David Norman
    David Norman Month ago +5

    I used to work in a shop that refurbished construction equipment and I started out in the paint department doing paint prep and worked closely with the painter as his sort of assistant at times, learning a lot about what he does and why. Parts of this video showed clips of people doing various parts of the job of coating infrastructure, buildings, and ships, and in a many of those you see them using equipment such as boom lifts and scissor lifts. Another layer to this whole process is making sure those machines are in good working order, and a part of that is the coating that protects them from the same elements as the infrastructure in question, for the same reasons. We took great care and pride in our work on both the paint and mechanical sides of the shop because we knew the safety of anyone using that equipment was in our hands. A lot of this video included things we made sure were right as we were doing our jobs to ensure the folks doing things like maintaining our infrastructure were able to get the job done as safely as possible. Of course, some of these things are monitored far more closely and to a tighter standard when you're doing something like coating a bridge, but definitely interesting and cool to see how similar the underlying focus of the jobs are, and how one supports the other. The paint job looking good is great and all, but the coating being properly done is the primary emphasis. And if you do the second part right, the first will follow.
    Sorry, just saw some specific equipment I know inside and out but havent worked on in a while and combining that with the topic sent me down a memory hole lol

  • wolvenar
    wolvenar Month ago +18

    This "myth" came from a popular tv series where one of the episodes was about the Golden Gate Bridge.
    One of the foreman said that they work continuously on the bridge. Painting and stripping being pretty much non stop. When they get to the end they start again from the beginning and continue with only one off repairs here and there where there's damaged paint outside of the normal painting. I don't know if it's true, but I clearly remember that interview.

    • Erik Peterman
      Erik Peterman Month ago

      Dirty Jobs?

    • wolvenar
      wolvenar Month ago

      @Michael Chui Sorry I don't remember which. It was a lot like "How It's Made" but I don't know anymore.

    • Dave D
      Dave D Month ago +4

      My dad was a painter on the GG, it's not a myth from what he said.

    • Michael Chui
      Michael Chui Month ago +1

      Do either of you know which "popular tv series" it was?

    • Mike Fochtman
      Mike Fochtman Month ago +5

      Now go look at the "Mackinac Bridge" in Michigan. About 3 times longer than Golden Gate. But fortunately, no salt. But freezing winters means the work calendar is somewhat shorter. So yes, maintenance is pretty much continuous, weather permitting.

  • Paul Haynes
    Paul Haynes Month ago +9

    Excellent, as always! Informative and educational, without being dull - I could easily watch one of your videos if it was an hour long.
    As for the Forth Bridge, It wasn't actually true, that they had to start repainting again as soon as they finished - but pretty close. To quote Wikipedia, " Such a practice never existed, as weathered areas were given more attention, but there was a permanent maintenance crew. In 2011, the bridge was covered in a new coating designed to last for 25 years."
    It is a massively complex structure (typical Victorian over-engineering) and in a terribly exposed situation (North Sea estuary in Scotland!!), so, continuously painted, or not, this is still an amazing achievement.
    I travelled over it recently, and it is a truly astonishing structure. You simply wouldn't believe the size and complexity of the engineering - almost entirely steel girders and millions of rivets! I just couldn't imagine painting that...

    • cr01
      cr01 Month ago +3

      @rpbajb All passenger services from Edinburgh to the north cross the Forth Bridge.

    • rpbajb
      rpbajb Month ago

      You travelled over the Forth Bridge? I was under the impression that it was used by freight trains only.

  • 0utlander
    0utlander Month ago +4

    Great video! But boy are you right when you say you're just scratching the surface. A couple other major difficulties of applying coatings that come to mind are relative humidity requirements and environmental requirements to capture 100% of the abrasive material during surface prep.

  • Pro -N- Stal1
    Pro -N- Stal1 Month ago +2

    Again, love the channel! And, thank you for sharing your family for your sponsor, I wish other makers did this, then just pushing an ad. As an EE and ME, I enjoy your views and enjoy the insite you provide to the engineering community!

  • LaserFloyd
    LaserFloyd Month ago +1

    You made a rather benign-sounding subject particularly interesting! Thanks to channels like this I look at bridges and other structures in a new light.

  • severo hernandez
    severo hernandez Month ago +4

    This video is awesome, thank you! I am a multi discipline inspector for a power plant and one of my areas is pipe and tank coatings. My company purchased me a brand new positector and all the attachments. I’ve been getting my self familiar with coatings and Cathodic protection these past few weeks so this video along with your catholic protection video served me very well. Thank you again.

  • KentD
    KentD Month ago +3

    Thank you again, Grady, for helping us laypeople know the difference between coating and painting! Great job as usual.
    BTW, how often/frequently is the Golden Gate Bridge painted (uh, I mean coated)?

  • chris roberts
    chris roberts Month ago +2

    I've do sand blasting and have been using ppg coating products for several years, love the process!

  • Liquid Flames
    Liquid Flames Month ago +3

    I don't work in infrastructure at all. I just like learning anything technical or scientific and this channel is awesome. So, it seems to me that coating a structure is kind of like putting a latex glove on a hand. It forms an unbroken, sealed jacket around the structure to keep all the bad stuff off the surface. As long as that seal remains unbroken and affixed to the surface, it is really hard for anything to touch the surface and start the corrosion process.

  • Vikingebo
    Vikingebo Month ago +1

    Nice vid! One small remark: the device that measures dry film thickness uses ultrasound, not magnetism.

  • Mike Flanery
    Mike Flanery Month ago +1

    Excellent, I learned a lot, especially re test equipment. As the PE with a large water system I was involved in many corrosion issues, including failure of prestressing wire used in 60" diameter prestressed concrete pipe, where the wire was drawn to 294,000 psi, where the high pH of the concrete coating was not enough to keep wire from rusting (hydrogen embrittlement was also a factor, among others). Frankly I had the best success in wrapping pipe in 6 mil pvc.
    Looking back, my biggest painting challenge was as an enlisted sailor in the Navy, where I was a disappointment in painting a Battleship, the USS New Jersey, We chipped paint, no sandblasting. I'd miss places and the Chief was not pleased. And I got no credit for using the right shade of grey paint. :-)

  • Mark Andrew Koval
    Mark Andrew Koval Month ago +1

    Amazing how these topics translate so well into everyday life. Weather, corrosion resistance, coatings, etc. is something I always consider in design, making purchases thinking about materials…esp here in the rust belt, East coast

  • Caleb Lewis
    Caleb Lewis Month ago +2

    Outstanding series, I wish you had done some samples that were just dirty (not oily) in the Navy we had a saying for painting, "once for dust, twice for rust"

  • Cy Early
    Cy Early Month ago +2

    Makes me think of my automotive lift, the company bragged that it was powder coated, but I am finding things that are powder coated don’t necessarily have good corrosion resistance or should I say there is no zinc primer layer. So rust will actually grow under the powder coating and all of a sudden large flakes of the powder coating just pop off , It might be years down the road but still. I also see this with trailer hitches. They look so nice but then the coating just flakes right off

  • Ryan Davis
    Ryan Davis Month ago +8

    This channel IS THAT GOOD that I would watch you watch paint dry Grady! And happily listen to you narrate it! 😂

  • Tom Lambert
    Tom Lambert Month ago +3

    I'm incredibly impressed by the work and investigation you've done for this series of videos is more than I've ever seen. Very high quality work.

  • Andrew Priest
    Andrew Priest Month ago +4

    Would you consider applying your expertise to a series of videos on how to best plan for and manage erosion around the yard? Very similar to your other ground water videos, but very practical to us home owners that have to deal with it on our own.

  • Green Pickle
    Green Pickle Month ago +4

    As a professional painter and super fan of the channel, I can’t wait for this one!

  • rtfgujihy uyhjigtfbr
    rtfgujihy uyhjigtfbr Month ago +1

    I was in the bridge building business for 5 years, 2 of those years spent in the paint bay, and nobody gave me as good of an explanation as to what we were doing as you just did

  • Dave Staggers
    Dave Staggers Month ago +5

    You do a very good job of providing clear and interesting descriptions of so many things that most people take for granted.

  • John Demore
    John Demore Month ago +1

    I recently found the use of dry ice as a rust and dirt removal and was amazed at the quality of the clean and the application
    possible uses

  • Evelaraevia
    Evelaraevia Month ago +3

    I feel like every time I watch a science and engineering video I learn of a new field of work. It's like the R34 of engineering "if it exists, there's an engineer specifically for it".

  • P S
    P S Month ago +2

    I'm in county road engineering and about to take my state Bridge Paintings and Coatings certification (we have quite a few bridges), I feel like I have a head start with this! Personally, I'm a big fan of weathering steel. Despite early concerns and certain exceptions, it can work great even in high chloride environments when all environmental factors are considered. Michigan used it on select projects from the mid-60s through 1980 but had issues in certain locations where the steel rarely had the opportunity to completely dry and the oxide coating never had a chance to form, resulting in significant section loss. Sadly MDOT has shied away from it ever since and spends a fortune coating structures (the entire structure including the concrete parapets and substructure components along with epoxy or healer/sealer deck treatments too). Michigan didn't have this stance until about 2003 and bridges since then have held up very well when combined with epoxy-coated rebar (used here since 1976, mandated 1980).

  • WiIdbiII
    WiIdbiII Month ago +1

    In my 40 years of working with steel , I've found that when you accidentally spill paint on something it tends to stick forever, opposed to purposely trying to paint it.

  • Peter Johnston
    Peter Johnston Month ago +6

    I worked for a very large company that made SCADA equipment for the electrical utility indusry. It's customer base was truly global in nature. A customer in Arkansas complained that the NEMA 4 class enclosure was leaking - which it is not supposed to do. Our investigation lasted several months, and we enlisted the expertise of the foam and adhesive manufacturing companies. The adhesive manufacturer, 3M, was particularly helpful and was instrumental in solving the issue. The gasket adhesive on he leaking cabinets was not compatible with he "surface energy" of the coating system used. It was simply a matter of matching adhesives to the surfaces they were intended for, and we never had another leaking cabinet. I would be interested in knowing about the engineering associated with adhesives and surface energy.

    • LizJ
      LizJ Month ago

      *supervisory control and data acquisition

  • itsmebatman
    itsmebatman Month ago +1

    Wow I didn't know just how effective these modern coatings are. Amazing. Although doing it properly and maintaining it looks to be labour intensive and thus expensive.

  • Mumbai Verve
    Mumbai Verve Month ago +2

    Just like pinhole and holiday detectors, there are adhesion test equipment which check the adhesion of the coating to the substrate.Something called a dolly is stuck to the coating and pulled out with a hydraulic puller. The pressure and the area of disbondment is measured.Prior to this a cathodic disbondment procedure maybe done by subjecting a sample to voltages which replicate the corrosion voltages in the environment. All this has relevant ASTM standards.

  • Svatopluk Čech
    Svatopluk Čech Month ago

    Thank you so much for the great insight. I value your experiments a lot. Data give the actual information bigger impact, it is more convincing and they give you space to think about it further. Thank you for sparking curiosity and for giving a peak into this fundamental principle of protecting infrastructure.
    I'm looking forward to your next video! Have a good day 👍

  • Conoalie
    Conoalie Month ago +5

    My favourite engineering RU-clip channel covering my local Scottish landmark ... this is weirdly fulfilling!
    My dad replaced some of the rivets on the forth rail bridge while he was still working as a welder. He brought some of the old ones home to me as a teenager and I didn't appreciate it back then!

  • ThinkTooMuch (b)
    ThinkTooMuch (b) Month ago +2

    Very cool! How 'bout covering hydrophobic and anti-icing coatings? And biomimetic anti-icing surfaces?

  • Hyper Nova
    Hyper Nova Month ago

    I'm super thankful for the content you provide us Grady. As a second year civil engineering student i sometimes feel kinda depressed reading online how dissatisfied people are working in this industry. This channel though restores my confidence in my major choice.
    Keep up the great work!

  • Lowell Martin
    Lowell Martin Month ago +2

    Was told by a fellow about a small business owner of an old Automotive Automatic Wash.
    The steel structure hadn't been regularly cleaned and painted for decades when the owner decided to have a couple of guys prep and paint it.
    The fellow said that it should have had parts replaced because scraping just removed the loose rust and if it had been blasted alot of the supporting structure would have probably looked like swiss cheese. They used a very thick epoxy applied by brush which didn't get into corners and other voids like mating surfaces.
    Needless to say within three months the epoxy was bubbling up in the worst areas. Basically the surface rust was held together with epoxy even as it became so bad it was separating from the rusted area underneath.
    Also he said the cure time wasn't near long enough for the epoxy and the carwash was put back into active operation too soon and had water now being collected behind the epoxy causing even more bubbling and hence the new layer of rust under the coating.
    This highlights the need for properly cleaning and coating at installation plus an inspection and maintenance on a schedule that fits the environment the metal will be exposed to.

  • Jan Vaughan
    Jan Vaughan Month ago +1

    Given a required bridge recoating period T, I imagine that employing N people full time to coat the bridge in T years could easily be a better business decision than bringing in kN contractors intermittently to coat it in T/k years each time - at least if T is sufficiently short and N is close to an integer.

  • Taylor Powell
    Taylor Powell Month ago +1

    I love watching these little experimental demonstrations that you make

  • T.J. Kong
    T.J. Kong Month ago +2

    If you want rock solid performance, do a conversion coat first. On small steel pieces, I like to Parkerize. It passivates the surface and leaves pores that can be filled with a zinc phosphate primer. At that point it's fairly bullet proof even without the top coat. On steel sheets, you can use something called Dupont 5718S I think. Similar to Parkerizing but without the requirement to boil your part. On aluminum you can use chromic acid to passivate the surface. But Erin Brockovich wouldn't like that.

  • CrankyOtter
    CrankyOtter Month ago

    I would love to see more rustomatic content. It’s a great rig with great documentation.

  • Locut0s
    Locut0s Month ago +1

    I work in a retail paint store and many of the things you mention here apply to the light industrial coatings we sell too, just on a smaller scale. We sell 2 component epoxies and many other such light industrial coatings and just like for larger projects it’s all in the nitty gritty details of surface prep and application. A lot of people applying said coatings don’t know the importance of doing said work, especially at the light industrial end where they aren’t out on critical infrastructure and so don’t have the training and education. Or they just don’t want to do the necessary prep and don’t believe it will make a difference. We have seen many costly failures as a result, these coatings costing easily $100 or 200 a gallon in places.

  • Adam Murdoch
    Adam Murdoch Month ago +1

    Great Video i have been working as a "painter" for the last 3 years mainly painting ships and there are area on ships that have similar conditions to your salt tank except you cant blast them if you are lucky you can get tools to mechanically prep them withing 4 years they will be rusted again its a nightmare the external of the hull is the easiest part of a ship.

  • SpaceCowboy
    SpaceCowboy Month ago

    You really can make watching paint dry interesting. Awesome content, thank you so much!

  • lnpilot
    lnpilot Month ago

    Love your videos. I'm an engineer (EE + CS), but I never thought I'd be interested in civil engineering until I started watching your channel.

  • Jacob W
    Jacob W Month ago

    Hey Grady, if I may suggest a topic, I'd love to see you do a video on how the repeaters on transoceanic fiber optic cables are powered. Every time I see a video on the cables the presenter just glosses over it, but seeing how much effort has to go into sending power over just a few hundred miles overland, I have to imagine there are some difficulties powering repeaters in the middle of the ocean, thousands of miles from the nearest generator.

  • grimreefer
    grimreefer Month ago +1

    I’m a painter and the surface prep is extremely important to paint adhesion and longevity. We almost always sand or remove rust or even clean metal surfaces with thinners. I often use pretty nasty paints and primers for metal surfaces in particular. People think of painting trades and envision just painting houses or something but people don’t realize how critical paints and coatings are to everything in our society and life. Your car, your house, a bridge or structure all need to have coatings applied to protect them from the environment/oxidation and it plays a vital role in our infrastructure. I do everything from residential to commercial to industrial work but most often i’m doing commerical and industrial coatings in my company. Sometimes being a painter feels like you’re a glorified cleaner because of how much preparation is involved, we’ve had to scrape black soot off of ceilings above magnesium cauldrons in factories after an explosion which is very dirty and dangerous. Being a painter can be very dangerous and we take it for granted. You have to get in awkward positions and be comfortable with heights, it’s taxing on the body

  • Leggir
    Leggir Month ago

    The enormous refinery I worked at never painted or put coatings on the majority of the steel beams. The few exceptions had concrete cast over the steel for increased protection and structural improvements in a fire. As the engineers described it, the rust increased the heat tolerance of the steel.

  • ZoonCrypticon
    ZoonCrypticon Month ago

    Thank you for your great video ! A question, is there an option of sputtering steel surfaces with thin layers of e.g. high velocity titanium or zinc ions, that would have a specific depth of penetration into the steel dependant on the applied voltage. Here I would assume that the weak points, where corrosion would start, become scarce and the bondage with the more noble or sacrificial metal stronger compared to galvanization or spray coating.

  • Btown2294
    Btown2294 Month ago +2

    Awesome video as always! In my industry, we deal extensively with corrosion on aircraft. That got me thinking about how unique the infrastructure of airports is. If it catches your interest, I’d love to see you do a video on airport infrastructure!

  • simon stucki
    simon stucki Month ago

    very interesting thanks! I guess the oil used as "dirt" also protected somewhat against rust, maybe a control sample would have been interesting!

  • Jaqui Greenlees
    Jaqui Greenlees Month ago

    One aspect that was missed, you have a perfectly done coating on a steel structure with no flaws in the coating at all.
    oops, the hot summer day has caused the steel to expand, now you have cracks in your coating. This same issue applies to aircraft and ships as well.
    The cold winter night shrunk the metal causing even more damage to the coating.
    While metals are fantastic building materials, the expansion and contraction they have adds breaking stresses to coatings designed to protect the metals from the environment.

  • Timbo!
    Timbo! Month ago +2

    Great video Grady! The one bridge I'm familiar with that *does* do the fabled continuous re-painting (at least in part) is the Mighty Mackinac in Michigan:
    “Every component of the bridge has an expected life cycle in the case of its paint,” said Bob Sweeney, CEO and executive secretary of the Mackinac Bridge Authority. “Each new full paint job will have a 35-year life expectancy - but to get that we have continually reapply some of the paint every 3 to 5 years.”
    One of my very formative memories that sparked my interest in engineering and infrastructure was Mike Rowe's Dirty Jobs episode he filmed with the bridge service crew.

    • Practical Engineering
      Practical Engineering  Month ago +2

      I suppose you could adjust your coating speed for any steel structure such that you finish right when you need to start up again!

  • danners430
    danners430 Month ago +1

    The Forth Bridge was painted continuously for decades - that’s no myth. Because it’s a rail bridge, it was easier to access, using semi-permanent structures which used the outside of the bridge for access. About 20 years ago a new type of coating was introduced which reduced the need for re-coating.

  • KF5HCR
    KF5HCR Month ago

    Thank you Sir,
    I appreciate your time to produce this high quality presentation.
    I have W8 red iron columns on my back porch, primed from factory and painted with latex top coat.
    Unfortunately, my wife's pool is adjacent to the porch.
    CHLORINE!!!
    I can't imagine how cathodic protection would be of use, but I don't know it all, so can you suggest a cathodic system and the best coating in this circumstance.
    Thanks in advance for your thoughts.
    Take care

  • Daniel M
    Daniel M Month ago +10

    I’ve always wondered if it was just a buzzword to call them coatings. Really interesting to learn the difference!

    • steviesteveo1
      steviesteveo1 Month ago +1

      Yeah, I always had a cynical suspicion that "coating system" just sounded more expensive than "paint"

  • Bill Scott
    Bill Scott Month ago

    The differences are often amazing. I learned that on the first set of water tower repainting specs I worked on. The document was bigger than the Dallas phone book.

  • Bruce Le Smith
    Bruce Le Smith Month ago +2

    I'm 1000% into watching Brady talk about paint dry! Even as a home/boat owner rust is the bane of my existence. Thanks for this!!
    p.s. I'm actually very surprised at how well the smooth and oily square performed. I wouldn't want that performance in a work setting, but as a diy homeowner those test results give me some hope! It's hard to think of a worse surface prep, but the film actually provided some protection.

  • Dwayne Penner
    Dwayne Penner Month ago

    There are couple of other common methods of measuring surface roughness: comparator gauges and optical micrometers, they are about on the opposite ends of complexity but even the comparator is surprisingly accurate.

  • NightCrawler1000
    NightCrawler1000 Month ago

    I am mind blown watching this video. It never even occurred to me that rust protection is an entire field in science and how important it is to prevent corrosion. I used to winner how the steel rails on the railway tracks never get rusted. They also don't seem to be coated. Does anyone know the answer to this?
    Also, does aluminium metal ever get rusted?

  • Honest Lyre'ed
    Honest Lyre'ed Month ago +7

    the only thing better than watching paint dry: watching coatings prevent rust :)

  • Eric Elton
    Eric Elton Month ago +1

    Your even voice, your proven intellect and your nuanced presentation make your channel a pure joy to take in, fine sir.
    I thoroughly enjoy learning from accomplished peers such as yourself. Please keep up the exemplary work! 👍

  • Just1Spark
    Just1Spark Month ago +1

    Well done. You should do a video on the myth of powercoat 'durability'. It seems to have gained this odd reputation of being the be all, end all coating. When in reality, it is quite inferior to even the most basic off the shelf liquid coatings.
    Ive so long pondered on how it got this reputation. I figured 1 of 2 possibilities.
    1. Since its 'baked on', folks perceive it as similar to baked on porcelain enamel. Which ofcourse, in reality, it doesnt even compare.
    or 2. Upon removal of a finished powdercoat via abrasive blasting or grinding, it proves very difficult. The reason this is true, is because of the heat produced from the blasting/grinding, the coating softens (it is just melted powdered plastic after all). So as it softens, it absorbs the abrasive impacts from blasting. And from grinding, just oozes around and turns to a horrible stinky gum.
    And for an extra dose of nonsense, powdercoat is also considered a "green coating". lol Its made from petroleum. It out-gas's when baked. And requires 350f+ temps to make. But most industrial process's also require it prebaked, or baked dry after its chemical wash prior to powdercoating.
    (Im speaking of the most widely used, most common, urethane powders. There are other more niche powders that fair slightly better.)

  • Todd
    Todd Month ago

    What a great video to open the eyes of many who have never been involved in the industry. Years ago starting off my pipefitting apprenticeship I was part of a large process piping project and spent time between fabrication and the "paint shop" where our fabricated pipe spools were sent for sandblasting and coating. Young and naive, I remember thinking how overkill the quality control inspectors were and being shocked at just how much time and money was spent on perfecting each step of this process. Of course with time and speaking with some of these inspectors I learned just how much importance it has and all the chemistry, engineering, and science that goes into it.

  • BB Wolf
    BB Wolf Month ago

    A great overview of this topic that anyone can understand, outstanding work as usual.
    I wish the videos had been around when I was in college and I hope they are being shared there these days.

  • Corey Gilson
    Corey Gilson Month ago

    This is an absolutely wonderful example of good, simple experimental design! I am going to show this to my sixth and seventh graders!

  • Buggy
    Buggy 29 days ago

    I love this video. I’m an industrial coater and sandblaster. Explanations I’ve always wanted the answer to, but no one would answer. Come to find out my coworkers just didn’t know how it worked either! Mostly “common sense” and “tricks of the trade” were as far as it ever was said.