Corvettes For Sale

Orange Peel Problem

Paint spray problemsQUESTION: I sprayed my Corvette last weekend with Arctic white Acrylic urethane paint using an HVLP spray gun with 1.4 tip. I first sprayed the urethane coat following a coat of urethane 2k primer reduced to act as a sealer. I tried to followed all of the instructions terms of mixing/reducing, etc. When I began spraying the color, I could see the rough texture of orange peeling forming as I sprayed.

I kept spraying without solving the orange peel despite slight adjustments to the paint flow at the gun, etc. The air pressure coming into the gun was at 45psi the whole time and I was using a moisture filter. I believe I was putting on too heavy of a coat as it seemed to use a lot of paint for an HVLP gun on this car. I used about 3 to 3 1/2 mixed quarts total and still missed a few spots where it's not totally covered. The temp. in the garage was about 75 degrees and I used medium speed reducer. I also developed a few runs and sags on the passenger door. SHEZZZ!

Since I did miss a few spots already, can I sand down the orange peel on the entire car and try to put a nice final finish coat on the whole car including covering the missed spots? Or is it better to sand the spots that I missed (slightly coated), touch up and hopefully blend those spots (one on inner wing and one by headlight) and then sand the entire car which is orange peeled and polish to shine? Which grit sandpaper is recommended in either situation?

I'm not using a top of the line HVLP gun but I believe it's more of my gun setup and technique causing this problem. Before I spray anything else, I will double check that I can spray a clean sweep on an old car fender first as spraying against plywood or plastic.

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Orange Peel is a Paint film on the surface after spraying having an uneven texture that resembles the skin of an orange thus the name Orange Peel. It is caused by the paint not flowing out ward, but globing due to thickness, air contamination, wrong thinner, surface contamination on the auto, and spaying technique. If it is serious it is best to cancel the spraying, let dry, re-sand and rework the paint mixture and the spraying technique. However, you will have the problem of the unused paint which should have been tested first on a clean piece of old metal (fender-hood) that was sanded also to check the flow and or practice.

orange peel in paint

Reflective orange peel

There are a number of reasons for orange peel, but thickness and spraying technique is usually a culprit for beginners. Fish eye can also be mistaken for Orange Peel and is due to contamination in the paint product, or on the surface, or in the air lines.

SOME CAUSES OF UGLY ORANGE PELL:

- Under reduction and/or air pressure too low.
- Thinner/reducer evaporates too fast for spray conditions.
- Excessive film thickness or piling on of heavy wet coats.
- Improper spray gun set-up.
- Improper painting technique.
- Contamination on surface of the car (Repels paint or fish eying effect)

- Old paint materials (outdated or exposed to air)  especially the harder catalyst will also cause orange peel.

METHODS OF REPAIR:

- Compound or polish to reduce surface texture.
- Or, sand smooth with 1200 or finer grit sandpaper, compound and polish to restore gloss.
- Or, sand smooth and refinish.

PREVENTION:

- Use proper reduction ratio and spray at recommended air pressure.
- Select recommended thinner/reducer based on temperature, humidity, air movement, and size of repair.
- Avoid heavy coats and excessive film thickness.
- Use recommended spray gun, fluid tip and air cap for the material being sprayed. Always adjust the gun for best atomization and balanced spray pattern before paint application.
- During paint application, hold the gun perpendicular and parallel to the surface. Adjust speed of pass, pattern overlap, and distance from the panel to achieve the desired appearance.

 

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