Powder Coating...no good

[Fassi]

I had my door handles powder coated at a supposedly reputable place...not happy w/ the results. There are dimples and imperfections around the hole on one of them that the supposedly couldn't fix "after four attempts" because of "oils" that come out of the hole. Has anyone else heard this? The other one came out ok after I sent the first one back. It looks ok from a couple feet away, but it's not amazing. Good thing I didn't pay much at all.

[KevinP73]

"Fish Eye's" occur in powder paint just as it does in regular paint applications. Next time ask if your powder coater will pre heat the parts first. This burns off a lot of the contaminants and reduces the chances of fish eyes

[RLJ]

When I had my door frames stripped of the bright dip and anodizing, then powder coated. The first time thru the process the same thing happened. Fish eye! The powder coater said that they had a problem last week and there was oil in some of there air lines and they would strip and recoat my parts. Same thing but not as bad the second time thru.

Later talking to a different powder coater he said that I should have sprayed primer sealer on first. Then had the parts coated.

Randy Jones

[Fassi]

That's interesting, the guy told me there was no primer that could be used. They said they do preheat, but that not all the oil is burned off in the process, and that there was no guarantee the next time would be better. I ended up paying a token fee and taking the handles. Now I'm not sure if I can touch up the imperfections somehow. So far I'm not a big fan of powder coating.

[Al G]

My handles didn't come out good either. In my case, the existing anodizing was pitted. We stripped th them to bare alloy, polished them smooth, then had them acid dipped to remove any contaminants. However, the pitting continued to 'blow' holes in the powdercoating, even though they were pre-heated and clean.

I have had this problem with pitted alloy before so gave up at this point and bought a pair of good second hand handles.

If anyone has any other solutions I would be pleased to know!

Al G

[79targa]

I just had 4 cookiecutter powdercoated in jet black and their was some trouble with 'bubbling'. They bead blasted them, heated them twice. The company didn't like it so they started the whole procedure from scratch and did it again. There were still several imperfections although I must say they were very very very tiny. They gave me half off the price and I was very happy. They look good enough to me and I got 4 rims powder coated for $100. Maybe its something in the german metal? I've powder coated all sorts of japenense car parts with not near this problem.

The copper color I added myself and is the body color of the 79 targa. I thought it would be easy at first. Hah. Here are the fronts. Hope to get the backs done by the weekend.

[kstylianos]

Fassi,

Common problem. Its called 'Out Gassing'. It was explained to me like this. Over the years, porous metals tend to absorb grease, and muck into their pores and when they are heated to high temps during the p-coating process, the accumulated muck and oils boil off causing the little bubbles. I would think this is espically on those door handles that you touch every time you get into the car. Even pre-powdercoat, the shop does sand/bead blast the parts, but even that can't get deep into the pores. The only remedy it to strip, and re-powercoat until the metal stops out gassing, which can take numerous attempts. The shop I took my part to, this was a common practice and gives you a 2 week turnaround time due to the strip/repowdercoat process to get a clean finish....they are also a little pricey.

The reason I know about outgassing is that they rushed to do something for me (at my request) and when I showed up the next day the lady said "uh, i need to show you something". I thought my parts exploded, cracked or were lost. Then she showed me these little bubbles in my hubs and al. crossmember and explained to what they were, what they were caused from, and what they do to remedy the problem. I told her just to give them to me as nobody would see them anyway....quite common.

[tobluforu]

I brought my door handles to a powder coating shop and he said "no way". To many problems with them like stated above. So, I sanded them w\200 grit paper. I then etched them. I then used zinc chromate primer and wurth satin black paint. Believe it or not, 2 years and no scratches yet.

[Fassi]

Thanks, guys, for all the responses. Since a lot of people recommend powder coating for the door handles, I never realized they were especially prone to "out gassing" and therefore a less than "Porsche" result. Actually, one of them came out ok so I don't know if I should find another solution or live with the marks. The fish eye is on the outer edge of the round part, so it may not be that visible if I mount that side facing down. The other blemish is around the cylinder hole and is not that obvious. In any case, I appreciate the information. If anyone has had any success with any other process, please let me know.

[Targa Dude]

Sorry guys there is no Primer for powder coat..unless you want your parts primer colored.
A good reputable powder shop will degrease parts prior to the Powder coating process.

Jorge (Targa Dude)

[Jeff Jagusch]

For what it's worth, I was told NOT to bead blast any parts that are to be powder coated, as the beads or parts of them can become inbeded and can cause these types of imperfections during the oven cycle.
It seemed to make sence to me?
I had my fan and housing powder coated with VERY good results and they were the ones that told me NOT to bead blast it!
I'm just curious if any of you agree?

[Targa Dude]

Thats because good shops prefere to do the prep themselves.. depending on the condition of the parts they may not require bead blasting.

Jorge (Targa Dude)