Powder Coatings vs. Hot "Ceramic" coatings

[saltfever]

My steel tire rims are showing signs of corrosion. You know that tattle-tale sign of slight rust discoloring were the center piece meets the rim or around other discontinuities. While I have used paint in the past I would like something better this time. I am considering either powder coat or one of the hot “ceramic” type coatings. The trouble with powder coat is the poor, or thin, coverage anywhere surfaces meet at right angles. Due to the electrostatic charge, particles don’t get deposited evenly, or in a thick layer wherever the flux field is distorted. Typically this happens in deep cracks or abutted surfaces.   Are Hot Coatings any better?  Do the hot coatings have salt corrosion resistance at least as good as powder coats? Is there a reason I should choose one over the other? Has anyone used hot coatings for stuff other than headers or other hot engine parts? My color is available with either technique. I don’t know which to use and your coments would be helpful.  Thanks in advance 

[saltfever]

Well that was a real bummer    I see lots of views but no response.  Anyway, many thanks to everyone that took a look at this thread.

In the hopes of providing more information to everyone that has a similar interest, I called a place that does both Hot Coating and Powder coating. It appears that there is no choice on car rims. The only process that can be used is powder coating. One of the secondary operations of Hot Coating is polishing to get the high luster. That is done in a tumbler (usually a revolving barrel with various media that is changed depending on the effect or the surface finish). Tumbling works well for manifolds, headers and just about everything except for car rims. Car rims have a denency to not polish well and they rotate inside the tumbler on their rims instead of tumbling. Because of that the hot-coat chips or flakes off of the rim edge and produces a poor finish.

I guess I will consider a powder coat finish. I have found a wide range in quality among powder coat providers. The biggest problem is "orange peel". Some think it is beautiful (a poor excuse for lack of heat control or oven timing). The search goes on.

If you have a different view of what I found out please share that information.  TIA 

[Peter Jack]

Thanks for the information. It advances all of our knowledge.

Pete

[Dr Goggles]

2 cents worth.

Is PC really better than paint?....can't touch it up, it chips, when it does let go the corrosion goes on unabated underneath it................do you run Moons?.......what's wrong with a zinc based primer and well applied enamel? It's tough , has sacrificial corrosion resistive properties and you can touch it up......

[Jerry O]

I have had parts both painted and powder coated. What I have seen with powder coating is prepping the part correctly makes a big difference in how well it bonds. I have had several frames powder coated and they were blasted with a fine media first. This give the coating something to grip to. So good that if you ever need to remove it to do any welding, you don't just sand it like you would enamel paint, you have to grind it off, then sand it smooth. I have never had it chip or come off. I seems to hold up much better to sand blasting from sand or salt when running at high speeds. As for the orange peel look, I think that comes from not applying it properly. I just had my streamliner frame powder coated and it has no orange peel and is as glossy as any paint job I have seen. The only down side to powder coating I have seen is getting it off to do repairs.  JMO

[Cajun Kid]

I agree with Jerry O.... 100% prep with light blasting or sanding before Powder Coating,,, bonds much better and bakes very smooth.

I do however prefer the "satin finish" powder coating over the Glossy finish,,, the satin will have considerable less orange peel than a gloss (in case it is not prepped or applied correctly) more margin for error with satin finish than with Gloss,,

Charles

[Stainless1]

If they are race wheels, just paint them.  It is very hard to repaint / re-coat powder coat or ceramics.  They will need repaint at some point, you can canodize them for $2 a wheel.... 

[grumm441]

I'm not a big fan of powder coating of frames and wheels as it can hide cracks and corrosion, especailly if it is not done well
Gray

[saltfever]

Dr. "G" the wheels are for my trailer without moons. Primer and paint have worked well in the past. However, in my experience if the PC prep is done right the finish is more tenacious than paint. I have had PC jobs that do exactly as you indicated and do chip. I also have a PC part under my truck that has survived far better than any paint would. The key is in the preparation and that is the trouble. The quality among applicators ranges widely depending on how busy they are, how much money they will make on the job, and their personal definition or commitment to quality. I have been disappointed a few times.

"Orange peel" is squarely the responsibility of the applicator. Some of the powders have a very narrow temperature vs. time range. In some cases as little as 15 degrees F. For example temps between 410F and 425F for 12 minutes. If you get outside that envelope you get orange peal. All kinds of complexities enter into the process but the bottom line is that some applicators don't even understand the temp swings within their own oven. Some don't even read the instructions on new powders. If you put a large mass of steel in a small oven the cold mass will pull down the temp of the oven temporarily. That exposes the powder to a too cold environment to flow properly, it takes a "set" and then will not smooth out. I have had applicators refuse to guarantee no orange peel. The bottom line; it is a PITA dealing with some of these companies to stand behind their work.

Grumm441 mentioned a very dangerous aspect of PC. In a critical structural application, where safety is a concern, PC will cover cracks. The FAA requires all aircraft to do various inspections (usually an annual). Certain parts of the inspection call for crack detection. PC is not allowed on such parts. A typical part would be the engine's welded tubular support structure (the engine mount). You might want to think about your car and decide if, or where, crack detection is important.

Thanks for all your responses.