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Mon Aug 26, 2013 6:02 am

Kindly bear with me.

Last fall, on the last warm weekend of the year, I used DuPont ChromaBase and their etching primer and 2K primer to paint my Porsche 914. I ended up with severe orange peel and had no time to take it back to metal and reshoot.

I used a HVLP gun and the tip diameter and gun pressure range that the DuPont spec sheet recommended. One of the earlier threads on this board recommended using much higher pressures to get an acceptable spray thickness and pattern. A reply on a different board recommended using more reducer. I'll experiment on a test panel, using those recommendations, before I reshoot.

Where I am now: I've sanded the color coat smooth with 400 grit and, due to the severity of the orange peel, have broken through to primer in several spots. I've also reworked some panel areas that I should have taken more time with initially, using Bondo, then covering with rattle can etching primer

My questions:

1. Will ChromaBase adhere to sanded ChromaBase, or will I have to take everything down to bare metal and start over.

2. On areas where I've used body filler and etching primer, can I shoot 2K primer over a larger panel area and then sand it smooth, then redo the color?

3. If yes to #2 above, will 2K primer adhere to the sanded ChromaBase areas that are not covered with etching primer?

Lots of errors on my 1st attempt at painting. Hoping for better results on the reshoot.

Tue Aug 27, 2013 9:33 am

Being a former chromabase user here is what you can do.

Chromabase is like f*cking water. The 1:1 mix makes it hard for coverage. Personally, I would never ever over reduce it. If anything, I have under reduced it for better coverage.

That said, I would hit the car with 600 wet. 400 is a bit too corse for watery dupont in my opinion.

Rebase the car. The stuff dries fast. I would see how it looks, you will get peel no matter who's paint you use. I would not use anything bigger than a 1.3 tip.

Once your happy with the coverage, and your feeling frisky, gently wetsand again with 6 800 just enough to knock down the peel. Then do one more dropcoat and clear it. This will kill any peel, but clear fills the peel to a degree anyway. Pork on the clear and wetsand and buff that out.

Hope it helps

Tue Aug 27, 2013 5:59 pm

Many thanks for the reply. I won't over reduce the color coat.

Could I get your advice on question #3 above? Once the color coat was on the car, imperfections of my body work were very noticeable. After color sanding the entire car, I reworked a couple of fender flare curves with a thin layer of Bondo, then covered the filler with rattlecan etching primer. I would now like to spray 2K primer/filler on the fender flares and sand them smooth prior to reshooting color.

So, will the 2K primer/filler adhere to the sanded color layer, or am I asking for more trouble?

Thanks for your advice.

Tue Aug 27, 2013 8:30 pm

depending on the products, they may not play nice together. try it and see what happens

Fri Aug 30, 2013 6:01 pm

What kind of compressor? How about air quality? There's lots of other factors in 'orange' peel. Usually it's not the paint but other things (temperature, air pressure, gun, user error etc).

Also underlying bodywork could be pre-orange peeled :)

Sat Aug 31, 2013 8:03 am

29 gallon Central Pneumatic 7.3 CFM @ 40 PSI. My HVLP gun is within its flow range.

Though I used the DuPont recommended pressure range for a HVLP gun when I shot color, Based on comments on another thread, I didn't use enough pressure to get the right spray size/pattern. Someone with ChromaBase experience recommended ~30 psi; I shot in the high single digits.

I've reworked several body areas and will reshoot 2K primer and block sand prior to shooting color again. Currently waiting for the run of high humidity weather to subside.

Thanks for the comments.