Powdercoating, a different slant.

[Gerry]

A few years ago I explored the "relatively" new process of powder coating with custom finishes. Powder Coating (PC from now on) has been around for ages but with the advances in recent years and an increase in demand, custom finishes have become more common.

I was lucky enough to run into a guy with a PC Company who wanted to experiment with some of the new stuff and that lead me to look into it further. I talked to him about Chrome PC and was told that it was not really very good and to wait for a while, so it could develop. There is a good reason I wanted to investigate the PC Chrome, based on many many reports of huge costs, long waiting time, loss of expertise in the chrome plating business, coupled to increasing pressure from the EPA to close these kind of industries. The number of people I talked to that had spent a small fortune on Chrome plating, only to have it rust or peel off after a couple of years was quite scary.

We all know that there is NOTHING like real chrome, but there becomes a point when....
well you know.

So my first experience of chrome PC was my 350 trans. As I have a client that is a trans rebuilder (and a life long friend) it was a little easier for me. The trans was stripped and I worked the case over after asking the PC guy what he needed for a finish. Most cases are really smooth for the most part, but flash lines and those little crevices need to be addressed. All I did with most of the surface was to wire brush it down with a cup brush in an angle grinder. The worst thing you can do, he told me, was to attack it with a grinder or flap wheel.

G

 

[choppedtop]

Looking at the photos of your transmission, it looks pretty darn good. Ya, it isn't chrome, but still on aluminum, it may last longer. I had lots of stuff (aluminum) plated when I had a motorcycle shop, with some sad results at times. I think for lots of chassis parts it will be fine. With the proper prep work, it is really pretty tuff. Repair would just be a redo, but with real chrome, it would also.

 

[old round fart]

I think I'm going to see if I can get that locally. I'm thinking headers and suspension would be good with that stuff.

 

[benT]

Headers should not be powdercoated. There is high temp powder, but it still doesn't get you in the operating range of headers. Header coatings are ceramic based and are wet-sprayed and cured (air cure or temp cured).

A little note about "chrome" powder (or Kentucky Chrome as we call it), it has a great aluminum appearance, but is suceptable to streaking and staining unless a clear cost is applied. Unfortunately, the clear tends to give a milky look to it. Our shop still does lots of it though!

 

[old round fart]

Thanks for the reply. Why does that trans look so good? How about a gold or brass color? I really can't afford real chrome. Where are you located?

 

[Gerry]

T How about a gold or brass color? I really can't afford real chrome.

Funny you should mention brass....
As said Chrome needs a clear coat to protect it but it turns the finish to silver. There is another way. Leave it bare and gently coat it with 3M hand glase. In fact as you will see we tried the clear coat, but....

 

[benT]

It can still look good with the clear, and I don't know if Gerrys trans is cleared or not over the chrome powder. I agree that the pic looks good. I'm not saying you have to clear it, but if you don't you will have to be careful on what cleaners you use and it won't be as UV stable. This is typical of all the chrome powders by the major manufacturers. The chromes are getting better, but they will never be in the same league as real chrome.

As for gold or brass, these can be achieved by applying a tinted overcoat over the chrome powder coat. I believe Gerry did his custom gas tank in a brass powder and it turned out great. The tinted overcoats tend to pool up or be a little darker in the edges, but still give a great look. Maybe Gerry can post up a few pics of his tank.

Our shop is located in Indy. We have several clients that have us do chrome powder in lieu of chrome for restorations like barber chairs and antique fans. They know it won't be as reflective as chrome, but it won't cost like chrome either!

 

[Gerry]

They know it won't be as reflective as chrome, but it won't cost like chrome either!

The way I look at it is, due to the 'low' cost, if it needs redoing in a few years, its still cheaper than real chrome. Plus its environmentally better. There are very few chrome platers left in the UK due to EPA requirements.

 

[Gerry]

Lets move on to the trans with lots of pictures.




As mentioned the first try by the PC company was to chrome and then clear coat afterwards. I got a call from Daz, the owner of the Company saying he was not happy with the finish and could I come by and see what I thought. He was not wrong, the clear had turned the chrome look into a normal silver finish. We had a chat and decided to redo the case again. His condition was that I do the prep, so I took a day off and set about it.

Not knowing if I was competent to do it he was a little sceptical, but after years of custom stuff the end result was, as he put it; spot on.

Next step was a blow off with an air line and a good tac ragging.






The brown paper thats on the various parts of the trans is a heat proof tape. It is placed anywhere that the coating is not wanted. In this case mating surfaces for other parts.
G

 

[old round fart]

I saw a product called Shark Skin you can put on glass bleeded parts to make them stay the way they look freshly done. Wonder if that would help. Another thought. Wonder what chrome powder followed up with a candy paint?

 

[Gerry]

I need to back track for a minute. Before the first try at Chrome PC I media blasted the empty case. Luckily we have a media blaster at the trans shop with glass beads in it for cases and parts. After the blasting; it spend 15 minutes in a hot wash followed by about 1/2 hour of water running through every port and place using a hose pipe. Finally it got blasted with compressed air, again making sure every hole, gallery and corner was covered.

The PC'er was happy with my blasting so he didn't have to do it again.
With things like a trans case or motor parts its worth having them back after media blasting to make sure every bit of media is removed.

(take a look at black chrome PC)

 

[RPM]

I wonder what powder coat does to the trans as far a temperatures. Does it make it hold heat? Smoothing it down would reduce the area of the trans case to transfer heat, coating it might make it hold heat in. Maybe not enough to even make a difference, any thought from someone that has one it?

 

[Gerry]

Ron. You are correct but in a T that will not work the trans that hard I'm fairly confident it will not be a problem. They say you should not paint a converter (I have), but the ones we get in from the USA are all painted, so who knows.

With the cleaning all done its time for the powder. positive to..... bla bla bla... you know the theory. This stage is not just a case of point and press. It takes skill to lay the powder so it has a uniform depth and does not overload in the little nooks and crannies. The guy in the picture has been doing this for years and was watching the part very carefully as he powdered it.

Just a note here. ANY grease or oil that is not cleaned out of a part will wreck the final result when its baked in the oven. As you may have seen in the background of the above pics, I also did my prop shaft and UJs. I cleaned all the grease from the spider with solvent and compressed air followed by a hot wash.

With the coating on its time for the baking. Daz said it cost him around $100 each time he fired the oven up so its with great thanks to him he did my parts between his normal classic bike frame batches.

 

[benT]

Sure glad natural gas is a lot cheaper here in the states. If firing up an oven for 30 minutes cost that, we'd be out of business quick. We run 2 ovens at about 1 million BTU's together all day for way less than that! If he's using electric, I can see that....

Without trying to hijack this thread, I wanted to add a few comments for all viewing this thread who may not know much about powder coat or the process:
1. When prepping for powdercoat, glass bead is not recommended. Glass bead media, will make your aluminum look bright and new, but it isn't the best for adhesion. Glass bead peens or micro de-burs metal, and leaves a smoother finish. Typically Aluminum Oxide 60-80 grit is preferred for PC and Ceramic Coatings, with fine red garnet being OK as well. Coal slag (Black Beauty) or steel slag should be avoided as they are really aggressive and can damage the material or not leave a smooth appearance. Most custom powdercoaters in the US will do the blasting and prep as. Even if a part comes in pre-cleaned and blasted, we will re-blast just prior to coating to make sure the part has the proper adhesion and to remove any oxidation.

2. The photos that Gerry is showing of the application shows they chrome powder being applied with the parts hot. This is not typical in most applications, but this method is used with some parts with lots of nooks and crannies. This is due to the Faraday effect. Since powder is applied electrostatically, at some inside corners, the polarity of each "fights" one another - like two magnets would do. "Hot-coating" allows the powder to stick instantly as it doesn't have time to reject. Normally the chrome powder would go on cold and look like a light gray baby powder before it is cured.

3. Ron: I doubt the powder has too much effect on cooling- we do trans cases and pans for Coan Engineering - They are one of the top race transmission builders and if they felt it was an issue, we probably wouldn't see any. If folks are concerned with this kind of thing, there are thermal dissipating coatings that we do on radiators, intercoolers, supercharger housings, etc that has been proven to increase transfer of heat thus cooling down quicker. Not in chrome-look though!

 

[Gerry]

Thanks Ben.
Correct we applied the powder hot. Daz prefers to run alloy parts through the oven to 'de-gas' them prior to coating. Glass blasting seemed to work for us, but as said they use a different media in their blasting chamber. Most of the heat comes from the converter. JW racing, whom we deal with here in the UK, said that holding a TC on stall for 10 seconds produces enough heat to take a bucket of water from ambient to boiling in the same time...

 

[Gerry]

Now comes a bit of 'fancy' stuff. My block is black and there is about 2" between the back of it and the firewall. I didn't want a distinct color change where the block meets the trans so we decided to fog the front couple of inches of the trans case in black to match the block. Also this give a graduated color change from back to chrome when you look at the underside of the car. I know that it is unlikely that anyone will see it but for me it made the whole drive train gel together.

After a second bake and at the other end of the oven it appears.... pics taken later at home. Might not be real chrome, but it works for me.

 

[RPM]

That looks really nice.

 

[choppinczech]

Looks better than chrome to me.

 

[butch27]

Looks great!

 

[rubicon]

looks nice.