[HN Gopher] Watching Paint Dry: The unexpectedly interesting sto...
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Watching Paint Dry: The unexpectedly interesting story of car
coatings
Author : rwmj
Score : 121 points
Date : 2023-05-23 15:40 UTC (7 hours ago)
(HTM) web link (edconway.substack.com)
(TXT) w3m dump (edconway.substack.com)
| Gupie wrote:
| Strange seeing "duco premier email a froid" in the vintage
| poster! I assume it is vintage? Anyone know what "email" means in
| this context?
| ShakataGaNai wrote:
| https://www.1stdibs.com/furniture/wall-decorations/posters/o...
|
| " Cellemail le premier email a froid Francais / Cellemail the
| best French cold enamel "
|
| So, I think it's french for enamel? Based on that link.
| tomcam wrote:
| As an old-timer, I can tell you that modern automotive paint is
| off the charts gorgeous end of a quality that would have looked
| like alien technology in the 1970s. One color you will see
| frequently is a metallic red that consists of the red pigment
| with fine metal particles that give it a deep glimmer. 30 years
| ago the only way you could get that was a very expensive coding
| process that required 10, 12, 20 layers of paint. Now anyone can
| get it on their Corolla for little or no markup.
|
| Another piece of trivia is that Fender, the guitar company, has
| often used automotive paints for its guitars. The reason is not
| just availability and durability, but that it accurately tracks
| recent color trends.
| csours wrote:
| There's a red tintcoat that's just amazing. It's red basecoat
| with a red tinted clearcoat. So much depth, I feel like I could
| wade through it.
| supportengineer wrote:
| The red paint on recent Mazdas specifically - I stop and stare
| every time.
| tomcam wrote:
| YES
| danzk wrote:
| Mazda Soul Red is what's called a "Candy Color". It's
| achieved with a translucent red layer applied over a base
| color layer. It's rare for an OEM to offer a color like this
| because the thickness the coating is applied changes the
| color and It's much more difficult to achieve a consistent
| color.
| greenthrow wrote:
| Fender only followed car color trends in the late 50s and early
| 60s. After that they went their own way (including natural wood
| bodies and many "interesting" color choices of the 70s.)
|
| Most Fender guitars sold today are still in those "custom" Duco
| colors from the late 50s and early 60s. (The standard
| Stratocaster was a burst color and the standard Telecaster was
| butterscotch or blonde. Any of the Duco car colors back then
| was a "custom" option for an additional charge.)
| tomcam wrote:
| I interviewed their #2 guy for a radio show a few years ago
| and he's the one who gave me that info. In fact, they follow
| lots of other color trends--right up to and including women's
| shoes (not joking). I called him out on it and he said, "Do
| you have any better ideas?" and that shut me up really fast.
| photochemsyn wrote:
| Great article, I agree that _" the influence of the chemical
| industry on modern products is astoundingly important, yet it's
| one of the least appreciated and most rarely told stories in the
| modern industrial pantheon."_
| legitster wrote:
| There's so much more detail you can go into in this stuff.
|
| Before the Model T assembly line in 1916, most manufacturers did
| something like 6 or 7 coats by hand because it was such thin,
| slow drying varnish. And to get that nice shiny enamel surface we
| are used to with hand brushes, they had to alternate the
| direction of the brushstrokes between every coat as well as sand
| it. In addition to time, this is a huge QC issue.
|
| Part of the magic of the all-black Model T is that you can just
| dip parts that can be dipped, Japan parts that can be Japanned,
| and pour paint on parts that cannot. At final assembly they will
| all be matched up together without any mismatching paint jobs.
|
| And we cannot understate how magical the introduction of
| asphaltum and naptha were to the paints. This was still pretty
| new technology then and the precursor to our modern petrochemical
| derived paints and even plastics. You could get thicker coats
| that dried faster. So paint could just be poured on and the
| surface tension would smooth the surface perfectly. And they were
| more durable because they produced a more flexible coat.
|
| One of the innovations of the Dodge Brothers (that Ford later
| copied) was that by using more metal body components, not only do
| you save on labor (working with wood is much more skilled than
| running a metal press) but that metal can withstand the much
| faster oven-baked finishes.
| 1970-01-01 wrote:
| >They all use electrodeposition and most of them use robots to do
| most of the car spraying. They are gradually beginning to explore
| replacing their gas ovens with electric ones to reduce the carbon
| emissions at plants.
|
| Toyota's electrodeposition and prep process can be seen here:
|
| https://youtu.be/DLav5xRvWUo?t=269
| mhb wrote:
| > These days, where we use enormous ovens to cure and dry car
| coatings, it is comfortably the most energy intensive and carbon
| intensive parts of making a car.
|
| I guess so if you don't count what it takes to make aluminum and
| steel.
| csours wrote:
| It would be better phrased as "most ... intensive part of an
| automotive assembly plant". Generally, the only big thing that
| assembly plants actually manufacture is the body (including
| painting the body)
|
| Once production was shut down at my plant because it was too
| cold and the natural gas company said they had to use the gas
| for residential customers.
| yread wrote:
| a friend (a paint engineer) believes there are massive energy
| savings to be had from the painting (baking). He was shocked to
| see how wasteful the process is in automotive plants compared
| to his other clients. All because the paint has to be perfect
| and last long
| [deleted]
| linksnapzz wrote:
| The paint shop at a modern car assembly plant can be 50% of the
| square footage under the roof, and cost 50% of the outlay, so
| half a billion for a new one at least.
|
| The change from VOC-borne to water-based paints was also a big
| deal for the environment. The lacquers did a good job, but
| imagine living in a neighborhood where several tons of toluene or
| acetone was being evaporated into your air every hour. In places
| like LA, this process was a _huge_ contributor to smog in the
| 1960s /70s.
| sokoloff wrote:
| On the other hand, at least the early water-base painted cars
| were prone to premature rusting, which has its own
| (distributed) ecological impact. My W210 Mercedes was
| mechanically great the day I sent it to the scrapper for
| excessive rust through on the rockers and underbody structure.
| Hundreds of thousands of car met such an earlier than otherwise
| demise.
| linksnapzz wrote:
| Glad you liked yours; the 210s and 220s and the original MLs
| were the nadir of Mercedes value-engineering when it came to
| many things, and rustproofing was certainly one of them.
| geepytee wrote:
| You should tour any of the Tesla factories, this is not the
| case.
| linksnapzz wrote:
| I'm pretty sure the cost is still a large part of the plant
| budget, as well as the floorplan.
|
| Also, Tesla isn't all automakers.
| hef19898 wrote:
| And Tesla is famous for trying things evrybody else knows
| are either stupid or just don't work economically when it
| comes to manufacturing cars. They sell it pretty well so,
| usually as some groundbreaking innovation of sorts, one
| that miraculiosly justifies the over hyped shares and cars.
|
| Not that Teslas are bad cars, far from it, but tue delta
| between perception and substance is larger than anything
| German "Premium" OEMs could have ever dreamed of.
| danzk wrote:
| Acetone is not considered to be a VOC.
|
| https://en.wikipedia.org/wiki/VOC_exempt_solvent
| csours wrote:
| I used to work in an automotive paint shop. When our exhaust
| scrubber (burner) went down, we had to stop painting cars. We
| had a 'budget' of VOC exhaust per year. I don't know when that
| went in, I imagine in the 80's or 90's.
|
| We switched to water based paints in 2013 and that really
| helped with the VOC.
| dghughes wrote:
| Take care of yourself!
|
| My neighbour was a car painter for decades he died of
| dementia. My Dad and grandfather had a house painting
| business in the 1960s/1970s using leaded paint for most of
| that time. Both Dad and my grandfather died of lung diseases.
| csours wrote:
| Yea, everyone in that shop was a little crazy, but we were
| never sure which way the causality pointed.
| eig wrote:
| For those of us who would like a little more depth in the history
| and chemistry of automotive paints (and more images/videos too),
| there's a great video essay by New Mind on youtube:
|
| https://www.youtube.com/watch?v=b_hgPinCZks
|
| I was quite surprised at how important paint actually was to car
| production.
| csours wrote:
| I used to work in an automotive paint shop. Another point of
| interest:
|
| There's a limit on the number of tries you have to "repair" the
| paint job, because the vehicle has to go through the oven again
| to bake the coatings. The trips through the oven affect more than
| just the paint. Some panels are filled with foam; there's
| internal sealant and glue, and external sealant. All of those
| things don't really love being baked too long. For the shop I
| worked in, we got 2 tries to repair.
|
| The main limit on repairs though? The windshield. Windshields are
| glued in with specialized urethane 'caulking'. They have to stick
| to the paint, and the paint has to stick to the body. That is
| only certified reliable with less than 5 trips through the ovens
| (in my shop).
|
| ---
|
| Paint is the hardest thing to get right in the whole assembly
| process, because there are so many process variables. Temperature
| and humidity (dew point) are the biggest besides the actual paint
| mix, but there's also unexpected problems from every direction.
| Our solvent paint process (pre-2013) was very vulnerable to
| siloxane (silicone) lubricants. Someone in IT applied some
| lubricant to a label printer and ruined hundreds of paint jobs.
| Livestrong bracelets also ruined at least a hundred paint jobs.
| Someone did weekend work on the roof? Congratulations on your
| dust quality spill (spill means a bunch of problems).
|
| All of the parts of the paint have to work together, and that
| includes things that you don't think are paint. The body is just
| dumb metal, right? Of course not. The metal panels have oil on
| them in stamping, and they MUST stay oiled right up to the point
| where the body takes it's first bath. If too much of the oil has
| evaporated, then you start getting corrosion, and in many cases
| you won't be able to tell until the vehicle gets to the customer.
|
| ---
|
| Paint shops have the most complicating routing of any part of
| automotive assembly. The electronic quality and build data has to
| be synchronized with the physical process, and that data package
| can be updated by several different systems. Then either IT or OT
| (operational technology) can make a routing decision, or an
| individual can use a key switch to manually change routing. "Why
| did this vehicle go here" is not a straightforward question to
| answer sometimes.
| bluGill wrote:
| > The metal panels have oil on them in stamping, and they MUST
| stay oiled right up to the point where the body takes it's
| first bath.
|
| I toured an assembly line a few years ago. The guide told us
| that in the 1970s they had teams of people watching iron/steel
| prices, when they thought the prices where at the low they made
| a massive order of all iron that factory would need for the
| next few years. When the factory when to just-in-time (sometime
| in the 1980s or 1990s) they couldn't do that anymore - but they
| also got to get rid of all the equipment to de-rust all that
| stored iron: since every raw material was shipped out as a
| final assembly in a week there was no time for significant rust
| to form and so they avoided a lot of problems.
| csours wrote:
| JIT assembly has SO many non-obvious implications. I had not
| heard of this one, thanks.
| geepytee wrote:
| You were painting bodies with windshields already bonded onto
| them? Seems like a good idea to adhere windshields after paint.
| singleshot_ wrote:
| I got the feeling they were in an auto body shop, where the
| paint might be trashed and the windows might be fine.
| csours wrote:
| Nope, the windshields go on top of the paint, but the
| requirements for the windshield affect the paint process.
| EvanAnderson wrote:
| Thank you for this comment. I enjoy hearing about intricacies
| of engineering processes-- particularly those that sound "easy"
| on the surface.
|
| This gives me a deeper appreciation for cars with plastic body
| panels. I also wonder if DeLorean Motor Company took any of
| this into account when they designed the DMC-12 with stainless
| steel body panels.
| csours wrote:
| Plastic panels are a whole bucket of issues in themselves. As
| far as I know, the color matching plastic panels are painted
| using a different process. That means the the front and rear
| fascia (bumper) of your vehicle are painted in a different
| plant (usually) from the rest of the vehicle. The colors have
| to match to a very high degree.
|
| And yes, that's a big reason why they went with stainless.
| Stainless steel does corrode, just much less visibly than
| regular steel. It also has different physical properties like
| work hardening etc. It's also VERY expensive. Salty napkin
| math says $10,000 more for the Cybertruck.
| EvanAnderson wrote:
| > Plastic panels are a whole bucket of issues in
| themselves. As far as I know, the color matching plastic
| panels are painted using a different process.
|
| I was thinking about "molded-in color" panels like the old
| Pontiac Fiero. That makes sense, though, re: painted
| plastic panels. They'd be a whole different ballgame and
| there's, I'm sure, interaction between the paint chemistry
| and the plastic chemistry that's probably pretty hairy.
| buildsjets wrote:
| The DMC-12 had stainless steel body panels, but it had a
| plain ol' carbon steel frame (designed by Lotus and similar
| in design to the Esprit) with an epoxy coating, and they have
| NOT fared well over the years. You can buy a new-build
| stainless frame for it, it only costs as much as a new
| regular car.
|
| https://deloreanindustries.com/8-1-0-stainless-frame/
| hef19898 wrote:
| Same with old Land Rovers, people belive they don't rust
| being all aluminium. Chassis are steel, and those rot. Plus
| some other bits and pieces. New galvanised chassis are
| available, getting the body mounted is the fun bit so.
| akiselev wrote:
| That sounds fascinating and complicated. I scratched my car a
| few years ago and decided I wanted to DIY a chameleon paint job
| instead of taking it to the shop (the car is worth less than
| the paint job if I pay retail). I've been slowly acquiring all
| the gear I need like a forced air respirator and sprayers.
|
| I was wondering how realistic that really is to DIY or if I'm
| kidding myself. Sound like even if I rented a stall in a paint
| shop for a few weeks, I won't have the time to finesse the
| technique to get a good end product, especially with how much
| more finicky I understand the chameleon paint to be.
| csours wrote:
| My understanding about chameleon paint is that it's very hard
| to match if it's not all painted at once. I think the
| difficulty may depend on your expectations for the final
| product.
| akiselev wrote:
| Yep from what I've read I'll have to do the full body in a
| single shot after spending several hundred man hours
| sanding down the old paint job and prepping the surface.
| I'm hoping in Southern California's weather I won't have
| much problem with rust between the prep and actual
| painting.
|
| I don't care so much about getting the matching perfect -
| "it was my first time" is a perfectly cromulent excuse in
| my social circles - but I do want the paint job to be good
| enough so that I'm not redoing it every year or two (I hate
| sanding). What should I exepct?
| csours wrote:
| I don't think I can help much more, sorry. The shop I
| worked in was completely automated and worked on new
| builds. In most ways, it's much harder to do a one-off
| repaint of an assembled vehicle.
|
| Only advise I can give is to get some cheap paint and
| some kind of panels and start practicing.
| crazygringo wrote:
| This is fascinating, thanks. Can you elaborate more on how the
| label printer and Livestrong bracelets ruined paint jobs? Was
| it something they emitted through the air? How would that be in
| concentrations to affect the paint job, what would happen to
| the paint?
| csours wrote:
| Silicone oils caused the paint to "run away", like putting
| soap in a greasy pot.
|
| Droplets were enough to cause problems - there's no hiding
| problems on a car's paint job and customers are VERY
| demanding.
| _tom_ wrote:
| So it was workers wearing the bracelet that caused the
| problem, not end customers?
| danzk wrote:
| Silicone has very low surface tension, imagine water on a non
| stick pan. If paint encounters a droplet of silicone it will
| shrink back on itself and form a hole around the
| contamination.
| wlesieutre wrote:
| That's a lot of work to paint 80% of new cars in the most boring
| colors possible
| nicenewtemp84 wrote:
| I worked in car sales for a decade.
|
| If you like model xyz, and you like red, but we only have it in
| Silver, you'll probably buy it.
|
| If you like model xyz, and dislike vibrant colors (very
| common), you won't buy the red one we have.
| wlesieutre wrote:
| It's true, if I weren't married I'd be getting Soul Red
| Crystal. Gorgeous color. But it's not for everyone,
| apparently.
|
| And the blue option isn't available, so white is it. If they
| had literally any non-red color we would've bought it, but
| they didn't.
| joezydeco wrote:
| I have a deep blue crystal Mazda but I also lust for that
| Soul Red color. It's amazing.
| wlesieutre wrote:
| Can't believe I'm paying $400 for white, but even with
| that the overall price beats what I could get out of
| another dealer 100 miles away where they had a deep
| crystal blue on the lot. Beats paying thousands of
| dollars of markups for literally nothing.
| crazygringo wrote:
| Then what's boring to you is clearly tasteful to the 80% of
| people buying them.
|
| I personally like to express my personality in other ways. The
| last thing I want is a car screaming some garish hue.
| Especially since I can do things like match clothes to my mood
| and the season, but I can't get my car repainted every day or
| every three months.
| wlesieutre wrote:
| It's not even really up to customers today, most people (me
| included) will take whatever color is available as long as
| it's not hideous. That's how I'm ending up with a white car
| even though I'm not enthusiastic about it. I guess
| manufacturers know that, so it's no problem for them to keep
| cranking out the whites and grays.
|
| Was talking to a Mazda salesperson recently and he was
| complaining that the first five or six of the new CX-90s they
| were being allocated are all white. Though looking at their
| website they have some red and dark blue ones on the way now,
| so maybe that was just the first production run.
| crazygringo wrote:
| It's still up to customers in the sense that car companies
| are cranking out whites and grays because that's where the
| most consumer demand is.
|
| If people stopped buying white today, Mazda would stop
| producing it tomorrow.
| wlesieutre wrote:
| I get that they do it because it's boring and
| unobjectionable, but I stand by my original point that it
| _is_ boring.
| crazygringo wrote:
| No, you're _projecting_ "boring" onto it. That's how you
| feel about what they're buying, not how they feel.
|
| I stand by my original point that it's _tasteful_.
| Classic shades of white, gray, silver, and black are in
| good taste, which is why people buy them. The buyers aren
| 't saying "I want a boring color", they're saying "I want
| a tasteful shade".
| wlesieutre wrote:
| Maybe we can agree that it's tastefully boring
|
| At least it's not beige, which would only be boring
| crazygringo wrote:
| > _At least it 's not beige_
|
| Ugh, if the 1990's are calling, tell them I'm not home!
| wlesieutre wrote:
| If you get a call from the 1990's tell Honda to bring
| back cypress green pearl
|
| Meanwhile at Mazda, I can see "zircon sand" working for
| the CX-50, but I'm skeptical on the Miata
| https://www.caranddriver.com/news/a41995585/2023-mazda-
| miata...
|
| Unless it's such a weird choice that it somehow
| transcends boringness?
| elzbardico wrote:
| Bach's fugues are tasteful, french cuisine is good taste.
| White and grey cars are just boring, the definition of
| good taste for the unimaginative petite bourgeoisie, the
| hallmark of conformity and middle-class sensitivity.
|
| I have a grey car, but I am fully aware this is the case
| just because I am a terminally boring middle-class
| denizen, mass-produced, and absolutely non-remarkable for
| history.
| mhb wrote:
| The gap between boring and garish is at least big enough to
| drive a Mini Cooper through.
| Swizec wrote:
| > Then what's boring to you is clearly tasteful to the 80% of
| people buying them.
|
| Apparently this has to do with how the economy is doing. When
| times are tough, people like boring car colors. Something
| about ease of resale and broad palatability in car
| dealerships.
|
| https://www.cnbc.com/2020/09/22/most-cars-are-painted-one-
| of...
| ughitsaaron wrote:
| > The conventional wisdom is that Ford decreed that all Model Ts
| should be black because that was the fastest-drying of all
| colours
|
| Is that actually the conventional wisdom?
| emmelaich wrote:
| These days people using vinyl wrap as well.
|
| e.g. if you see a Tesla in other than white, red or blue, then
| it's probably:
|
| https://www.3m.com.au/3M/en_AU/p/c/films-sheeting/vehicle-wr...
| dekhn wrote:
| these innovations spread back into the normal paint world, I've
| come across a number of things about modern paint that show it
| was first developed for cars (and mostly GM/Ford). Automobile
| primer is great for covering 3d prints.
| ZeroGravitas wrote:
| Masking tape being a notable example:
|
| > By the early 1920s, two-toned cars were the rage, and that
| created a major headache for the automotive industry. To craft
| this duo-tone look, one portion of the car had to be masked off
| while the other was painted. The problem was nobody knew how to
| do this well. So automakers and auto body shops improvised.
| They glued old newspapers to the body and windows with library
| pastes, homemade glues or surgical adhesive tape. This helped
| create a sharp demarcation between the two colors, but the
| adhesives stuck so firmly that trying to remove them often
| ruined the paint job.
|
| > At the time, 3M primarily manufactured sandpaper and other
| abrasives. One of Dick Drew's jobs was taking samples of
| waterproof sandpaper (another 3M invention) to nearby auto body
| shops for testing. One morning in 1923 he walked into one of
| these shops and overheard "choicest profanity I'd ever known."
| Yet another paint job was botched and the worker who'd done it
| was furious. Drew had seen this occur on many other visits, but
| this time he spoke up. He could, he said, produce a tape that
| would end the painter's torment.
| AlbertCory wrote:
| There are actually videos on YouTube of watching paint dry, e.g.
|
| https://www.youtube.com/watch?v=PLOPygVcaVE
|
| 1.3M views! I found the plot a little thin (drum roll).
| aidenn0 wrote:
| I think you meant rim-shot, not drum roll?
| david422 wrote:
| Gonna watch that on 1.5x speed.
| intrasight wrote:
| Great article. Reminded me of this article about the mineral
| "Fordite" that I recently read:
|
| https://www.boredpanda.com/car-paint-deposits-fordite-detroi...
|
| Many dozens or perhaps hundreds of "watching paint dry" cycles
| results in some spectacular agate-like specimens.
| doctorhandshake wrote:
| Might be a little OT but I was hoping this would include more
| discussion of the contemporary interplay between aesthetics and
| paint chemistry / technology.
|
| I know there are some interesting stories behind titanium dioxide
| production, the use of which is critical to making paints vibrant
| and opaque [1].
|
| Further I have a pet theory that the recent trend in 'flat'
| automotive paints (without the apparent depth and larger
| suspended metallic flakes common in decades prior) has been
| enabled by some kind of technical advance as well, not just a
| change in consumer tastes, although I have no evidence to support
| the idea [2]
|
| [1] https://www.theverge.com/2014/3/6/5476904/china-stole-the-
| co... [2] https://www.latimes.com/business/story/2023-03-07/la-
| fi-car-...
| notjulianjaynes wrote:
| >Further I have a pet theory that the recent trend in 'flat'
| automotive paints (without the apparent depth and larger
| suspended metallic flakes common in decades prior) has been
| enabled by some kind of technical advance as well, not just a
| change in consumer tastes, although I have no evidence to
| support the idea.
|
| I've wondered about this as well. One theory I've had is that
| older paints used lead based pigments which gave a glossier
| finish, but are no longer used. I also do not have any concrete
| evidence to support this aside from pointing out that
| automotive paint was exempted from the 1978 (US) lead paint
| ban.
| [deleted]
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