I'm going to have a car chassis powder-coated. The issue I'm having is that some people say powder-coating is brittle and will chip when struck by small rocks. Yet I read elsewhere that powder-coating should not be used on suspension arms because it hides cracks, that since the coating is flexible and stretchy... it'll bridge the crack... well that's not brittle is it.

So what is correct? Okay, so maybe there's two types of coatings... so I call up the place and they say nope, there's only one type of coating. Or are they just saying that because they only use one type? I always get skeptical about peoples intentions when money is involved...

Anyone here in the industry who can give me the straight story? I'd like to get educated on this before "going to battle."

 

I actually worked as a painter in a powdercoating plant. Powdercoating is a very strong and durable type of finish. A properly coated; baked at proper temperature part will NOT flake or discolor. If you are going to do high temp parts (manifolds and turbos, chargepipes are not high temp) than make sure they coat it with a high temp powder. I believe it was Dupont that had powders that were good to 1600 degree. This is of course if the person who is applying the coating has an oven that can bake the part at the appropriate temp.


The only difference in powders that I've seen is the high temp. But besides that all powders are the same weather they're flat black or the dupont color changing bling-bling.


But powdercoating is the strongest coating available, but remember its still just a coating and not indestructable. When its sprayed on its very thick and durable. When we painted we plugged bolt holes with rubber inserts and when the parts came out of the oven the rubber parts were also powdercoated. Since the powder doesn't stick to rubber you could pull just the finish off (kinda like paint chips) and you could crush the finish with your fingers and it wouldn't crack. The only way to break the finish was to actually rip it.


Summary: Powdercoat is not indestructable but IMO its the most durable finish on the market and when powdercoating chips and flakes, its usually becuase of the painter.


Also, what coating do you think is stronger than powdercoat?? The only other option I can see is rubberized undercoating.


Modified by USDMforLife at 12:15 PM 10/25/2004

 

There are several different types of powders that are used in the industry. First are something called thermoplastics which include such formulations as halar and kynar. These are a freeflowing for life coating which are used mostly in the medical field and are fully functional coatings with great electrical insulation properties. Than there is theromosets which are commonly used for aethetic reasons and include 2 main types formulated with the resins of epoxy and polyester. These thermosets are the powders you mostly see used on tv with american chopper and all the other people out there offering powder coating services to get a nice pretty finish. You have to ask yourself a few questions first. Since there are so many different formulations, what are most important to you.....UV resistance, abrasion resistance, corrosion resistance, solvent resistance, hardness, and/or long term weatherability. My suggestion to you is to use a epoxy powder on your frame. It has no UV resistance, but how often is it going to see the sun? It also has great impact resistance, abrasion resistance, hardness, and flexibility. The only 2 downfalls of epoxy are they are not easily applied, but thats not your problem, they have 0 uv resistance, but it will never see sun anyways, and it is limited in colors aswell as higher to get in gloss finishes. If you are going for a fancy color, your next best bet would probally be a hybrid powder. Hybrid polyester powders are similiar to epoxy formulations, except they have a slightly softer film, but have a slightly higher UV resistance aswell as a wider range of colors, but still, not very many. If either of these are what you are looking for you can go into your Urethane and TGIC polyesters, which offer a huge variety of colors, in all kinds of gloss's, including metallics, and translucents, dormants and so on and so fourth. All you really really pretty powder coating jobs you see, are mostly of this formulation. Being they are a powder, they are far superior to paints in many areas, but the one downfall of these 2 powders is harness, and chemical resistance. These coatings will scratch easiar and show more (higher gloss shows more imperfections), and salt and other harsh chemicals will discolor the coating. Powder coating is a great coating, and now pretty much the industray standard over liquid spray for many reasons, mostly cost efficiency. When its done right, this stuff is tough as hell, but when done properly its weaker than paint. If you have any other questions give me a call or pm me, or post here.

 

Good stuff! Yeah it's a tube-frame chassis for a race car, and you're right, it won't see much sun because it'll be under a shell. What sun it does get will be through window glass or Lexan, both of these blocking UV. Originally I liked the blingy neon blue but "matured" through that fad... I'm going with a plain navy-gray.

So, if I prioritize the requirements, well, I hate rust, so corrosion protection is first, but that can only work if it doesn't chip or scratch off, so I guess abrasion resistance is first, followed closely by corrosion protection. I don't want something hard since that to me translates to "brittle" and easy to chip. Having it slightly flexible seems like a good thing. Oh and resistance to gasoline, oil, and the dreaded brake fluid would be nice too.

So based on this and your note it looks like epoxy is the first choice followed by a hybrid polyester, yes?

Since I have lots of rivet holes, what is the consequence of not plugging them? I know I have to drill them out, but how will the powdercoat react to being drilled? I guess it goes back to hard it is, huh? It won't hurt to ask what they'd charge to plug all the holes. BTW, I'm guessing they plug the holes after sand-blasting, which is too bad in my case since I worry my tubes will get full of sand.

 

Well, for your instance, a epoxy or hybrid would probally be best for long term durability with the sacrifice of a really nice glossy bling bling look and variety of color. Now if you want it to look pretty, your best bet is a TGIC polyester. I use TGIC's on wheels i powder coat, and it has great weatherability, the only thing is its not the best when it comes in contact with strong solvents (slight discoloration can occur), and its a little but softer so it can mar or scratch easiar from curbing etc. That is where hardness comes in, the harder the powder is, the harder it is to mar. Powders are organic polymers, aka plastics, so flexibility is never a problem. As far as the rivet holes, drilling them out is no problem, dont worry about plugging anything unless its threaded. They should also be able to get all the media out of the chasis before coating as well, cause if they dont it could contaminate the final finish.

 

re: crackes in suspension question! i have built some long travel suspension kits,a-arm and i-beam and from my expierience from researching long travel suspension i was showed some suspension that had failed (trophy truck suspension) and the powder coat actually magnified the cracks, so i think it can be kinda benificial for more than just being durable. also, if trophy trucks can get the **** beat out of them in the desert and with stand the beating they get on their paint jobs (chassis/suspension) then i dont think you will have a problem.

 

It just goes to show what "knowledge" is floating around out there. I'm going to powder-coat the suspension arms. I know people used to chrome plate them but that's not perfect either. Besides I was looking for an excuse to add a contrasting color - the neon blue like on the 350Z fits the bill... Thanks for all the help guys.

 

Its very true, especially in powder coating with all those people buying those at home hobby kits. Everyone coats a few parts, and than thinks they're a "pro". Although i dont know everything there is to know about the industry, i like to spread what truth i do know, and clear up others mistakes. The powder coating industry has taken a HUGE hit because of these hobby people spreading lies. I guess its like that everywhere though....lots of car forums have a lot of know it alls aswell!

 

You'd be surprised what you can find on Honda-tech....

I had a question about finances and credit...I got it straight from a banker!!! nice

whatever your question is...I'm sure honda-tech has an answer

 

Sometimes right, sometimes wrong . I guess thats the good part about HT, so many people from so many backrounds you're bound to get a good answer!

 

That's some good info. I've been thinking about powder coating the bumpers on my truck since a buddy of mine just bought a new set up for his shop.

 

The home powder-coating kits are pretty cool, I have one. The problem is the oven. You can only do what will fit in your oven... which seems to be surprisingly few items since you always want to do something bigger...

 

Build a bigger one...very easy to do and inexspensive when you consider how much more of your own stuff you can do.

 

Yeah, but it always comes down to the question, "Do I want to build an <oven> or build the car?" Working on the car is the only way it gets done! At some point you have to draw a line and acknowledge that, while you can build something, your time is better spent doing something else. I ask people here that question who entertain ideas of building their own welder. If you want to build a welder, great, but if the original goal was to build a car, then build the car and just buy a welder.

On a related note, as far as having time to work on these projects, I disconnected our cable TV. It's been a year now and I keep waiting to miss it... hasn't happened yet.

 

also, you might want to consider nickel plating! it looks real nice/race and is also pretty durable!

 

Hey, have you been reading my site? Since I can change my mind like a presidential candidate, I may indeed be going to electroless nickle plating on the suspension parts.

 

yea some excellent info

 

Regarding plating, I keep reading that hydrogen embrittlement is a bad thing, and electroless nickle is one of the processes that causes it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">Regarding plating, I keep reading that hydrogen embrittlement is a bad thing, and electroless nickle is one of the processes that causes it.</TD></TR></TABLE>
lol, i didnt know you had a web site! also, you wont be having to worry about hydrogen embrittlement unless you are plating aluminum,titanium or stainless being that those materials are most likely vulnerable to corrosion with injected hydrogen processes.

 

Question: Can you powder coat an engine block and tranny case?

 

yes it just takes alot of masking for the powder coater!

 

i was wondering if u can powder coat engine that was just sleeved with dartons , someone told me it may affect the block because high temp. which is ab 200C , parts staying in that temp for ab 50min ,

what do you think??

 

Supposedly you can also do larger stuff with big UV heat lamps. I bought a couple of UV lamps and was going to try doing something 'odd-shaped' but haven't gotten around to it. I think it takes longer, but should work.

I figured it would be good for stuff like bike frames, etc.

 

speaking of the home powder coating kits, do any of u reccomend a certain one/brand?

 

Easiest kit would probably be one of the Eastwood kits.