The Latest in Waterborne Technology for the Aerospace Industry
We accept Visa We accept Mastercard

Orange Peel or Craters

Posted: Thursday, April 28, 2016 12:56 AM Quote
I'm shooting Ekopoly Premium and can't seem to get the finish right. If I "sneak up on the gloss" with many light coats I end up with orange peel. If I do the fog coat + wet coat, I get craters.

Pictures are here.

The picture showing orange peel is EPP over Ekofill, shot with a fog coat, then many light coats after the fog coat tacked up.

The picture with the craters was EPP over sanded EPP (didn't get enough coverage on the first coat, so sanded out, wiped with isopropyl alcohol, and let dry), fog coat then wet coat. The fog coat looked fine, no pinholes or fisheye, but the wet coat ended up with many craters. This has also happened with EPP over Ekofill when using the fog coat + wet coat.

Gun is a Devilbiss Finishline 4, 1.3mm tip. 70psi feed, 23psi at the gun, volume knob turned out 3/4 turn, moving slowly on the wet coat instead of turning up the volume, as suggested by Dan at Sun-N-Fun. Plenty of volume, air seems to be clean. Paint mixed 4:1:1 by weight (12 parts paint, 3 parts catalyst, 3 parts water), 20-21 seconds on the viscosity cup.

Once in a while I get lucky and get a decent coat, with just a little orange peel, but I'm sanding off and reshooting a lot of expensive paint. Any advice would be much appreciated!
Posted: Saturday, May 7, 2016 10:57 PM Quote
I had the same orange peel results this week as you have. I sprayed my own Cub project, first time spraying anything, two years ago and didn't get any orange peel except on one airleron when my paint was too thick. I sprayed someone else's fuselage this week using the 4:1:1 ratio and had orange peel. The ratio I used on my Cub was the old ratio of 3:1:1, but I actually divided by 2.8 for the water. It went on very smooth. I use a Devilbliss Tekna Pro and never open it up more than 1/3-1/2 turn. Lots of fogging, lots of passes. I use the same opening during the wet coat, just closer and slower. I sanded the fuselage with the orange peel, tough paint to sand, and repainted using the old ratio. I painted it today, no orange peel. I checked the viscosity with the cup today, and I was right on with just a touch of water left over. I usually don't check, just weigh and mix, but I checked today out of curiosity. Your picture of orange peel looks like my results this past week. I think the paint is too thick, the most common cause of orange peel. You might try painting something small, or poster board,  that wouldn't be a big pain to sand if you didn't like the results, with thinner paint and see how you like the results. I would be glad to talk to you if you want. Two oh eight three fife one three niner ate zero. Have fun.