A question for you painting experts...

[Todd Burch]

I've been painting white gloss alkyd enamel today, and as I've been painting, I've been thinking about what I was doing (a good thing, I guess!)

I have a lot of crown and casing to install, so I figured I would pre-paint it, then touch up the nail holes and seams after I nailed it up. I started with finger-jointed pine. Yesterday morning I sprayed Kilz primer with my conventional gun with 2 quart remote pot. I went on pretty good straight out of the container - no real issues.

This morning, I went to spray the enamel, undiluted, and I got more texture than atomization. I'm using an Asturo G70 gun with a 1.4mm tip set. My pot pressure was about 12 lbs and air pressure varied from 35 to 65, but I still couldn't get good atomization.

I added a splash of paint thinner to the paint, and while it was noticeably thinner, it still did not atomize well, (it was better), but it also left hundreds of small pin-hole like craters everywhere, as it did not flow out well.

By then, I was fed-up and poured the 2 quart cup worth of thinned enamel into a bucket and started brushing. It did brush well though, as I typically try to brush this stuff undiluted. The trim will definately need a second coat though.

So, my question(s). I know that adding paint thinner will thin the paint. I have also read that adding linseed oil will help - but what will it help with? Would adding boiled linseed oil help with spraying? If I had a viscosity cup, what cup and how many seconds should enamel be at to spray? I could have got my airless out, but cleaning it is such a hassle for small jobs. What would you have done to get this 170 linear feet of moulding painted? Also, let's pretend I was in a hurry to get two coats on in one day. Could I add japan drier, and how much? What are the consequences? Yellowing?... even though this paint will yellow on its own anyway? Should I always dilute oil based when brushing? How long should I have to wait to sand between coats? Even this evening, it's still a little tacky.

Thanks, Todd.

[Kirk (KC) Constable]

Only thing we spray with the Asturo is lacquer...but every time we've had a problem with that rig it was related to the check valve in the lid of the remote pot. If it's not clean, the gun will spray...but it'll spray heavy or thin, atomized well or spitting...and sometimes a mixture of all four. Very frustrating...and no fiddling with the air or material mix will fix it until that check valve is cleaned up.

Just a thought...

KC

[Todd Burch]

Thank Kirk. when I called my suppplier, they gave me the check (poppet) valve as the first thing to inspect when I called them about spitting when I was applying the primer. The poppet valve was clean and working fine. The packing nut around the needle valve was a bit loose and I tightened that. I bumped the pot pressure up a bit and cleaned the tip and the spitting went away.

[Phil Phelps]

I think your problem is in the gun or tip and needle. 35 lbs of thinned enamel should flow and lay out well. I can't say how much to thin your enamel, but the least is best. I'd start at ten percent and work up. Just so it lays out and doesn't freckle. The trouble with spraying alkyd enamel is the sheen is affected by the thinner and the atomization. It gets flatter. If you brush a cabinet carcass for example, and spray the doors, you can tell the difference. Japan dryer can discolor whites, but darker colors I get away with. I haven't used it in dacades. About a day on drying, especially when brushing. You can use Penetrol to aid in the flow of the enamel in spraying and brushing. I really like it for brushing. Read the directions. I like to tint my primer, if it is a color, and paint molding as you are doing. In the "sewing room", I painted the crown molding to the finish before installing. Spackled the nail holes and touched them up. Looks fine. And, lastly, I love the airless with the fine finish tip for enamel. Thinned about five percent and it lays out beautifully. You know about the clean up