Spraying Oil Paint with a Pressure Pot

Some finishers get good results with oil by over-thinning. August 12, 2014

I'm using a two quart pressure pot with single regulator and lvlp gun with 1.8mm tip set. I'm also shooting exterior grade oil based primer and paint for the first time. I canít seem to get a good finish no matter what I try as far as settings. I've tried different pressures from 10 to 30 psi and all sorts of combinations of material versus air at the gun. It either wont atomize and comes out in globs or in orange peels and lays out bumpy. Is it possible to get a good finish with oil based paint and this gun/pot setup? I'm thinning the primer or paint about 5% with MS. Iím not using penetrol yet.

Forum Responses
(Finishing Forum)
From Contributor U:
My guess is you need more thinner. I spray exterior oil every now and then on my interior shutters to match what customers have used on the surrounding trim. I probably push going over the edge of what the paint company would suggest, but this stuff is usually pretty thick. I mix in one quart batches. I start with one tablespoon Japan Drier, add at least four oz of mineral spirits and then fill quart container with the paint. Sometimes, depending on the brand and particular paint, I may add another half oz of thinner. So at times I am using between a total of five and a half oz which is way more than 5%. I use to be concerned about this much thinner, but have never had a paint failure. You do need to be careful as the higher the thinner ratio can affect the sheen or gloss of the paint. Spraying multiple coats for build usually takes care of that issue. Play with the formula, but test using more thinner and see what result you get.

From contributor F:
I just sprayed oil based on a project and it came out so good that I was amazed. Contributor U gave you good advice, I think your trouble is you need more thinner.

From contributor M:
Spraying oil base is almost like latex and I use a 2.5mm tip to spray latex.

From the original questioner:
Thanks Contributor U. It turns out thinning more was it, at least for the tip I'm using. Maybe I wouldn't have needed to thin if I had the 2.5mm tip. At any rate I'm very happy. I was bummed at the thought of having a brand new setup that was so limited.

From Contributor U:
Glad youíre seeing improvement. I should have mentioned that while the Japan Drier is actually helping to thin the paint, I do add it more for the faster dry time (drying while painting vs drying for handling), rather than for thinning. The paint with drier added does readily accept a second coat quicker without runs. Getting more coats on the product helps offset that dull finish you can get sometimes from adding too much thinner. At least that is what I find when painting shutters, cabinets or other products would seem to the same thing.