I want a very professional looking job and plan to use an airless sprayer to spray forty doors. Thirty of the interior doors with oil based paint and ten with clear poly. In the past I have had a lot of difficulty with runs on doors using latex primer and paint. The opposite is also an issue; I sometimes applied too little material while attempting to reduce runs, which affected the sheen consistency. I have a high quality Graco pump and gun, use the lowest pressure that gives me a good pattern, a very fine orifice to limit the material volume, and I did not thin the paint. (I have only sprayed water based paints – no experience with spraying oil based paints.) The cause is probably due to my lack of skill/technique.
To compensate, I am thinking of removing the doors and laying them flat to spray them. This causes new problems, though. I can only spray one side at a time, airborne particulate will settle on them, and since I want to spray 40 doors, it just doesn’t seem practical. Any suggestions? I’m still considering spraying them in place, but the carpet and furniture in the house could be easily damaged.
I saw one post that suggested the following: “Instead of thinning oil-based paint with paint thinner/mineral spirits, thin with a little VM&P naphtha, as it flashes (dries) quicker and thus avoids runs better.” Would this help a lot if I choose to spray on vertical surface? Would this introduce more difficulty with consistence of the sheen? (Experience level ~ 200+ total gallons of airless paint spraying in ~ 40 sessions.)
From contributor R:
To spray both sides of the doors I suppose you need to do them in place.
If you use an airless for this application, make sure to move faster than a crippled rabbit being chased by a hungry lion on the African plains. If not done properly, you're looking at some decent runs. Don't try and cover everything in one pass - multiple coats work better, but still move quickly. An airless will put out the material no matter how it's set. Do you have access to a conventional spray setup and a pressure tank? That would be my choice.
Naphtha is okay, but don't thin it too much. I would also add some Japan driers too. A professional finish is mostly dependent on prep work even if it means tarping the carpets and masking the walls.
It's best to spray flat and overlap 50% each pass. Also angle the gun 5% perpendicular to the door to aid with spray back. Use a light at head level shining on your door and opposite from you. Keep the gun 10-12 inches from your work, start on the far side and spray and walk doing first side, bottom, other side, and top. Next spray the flat of the door going from side to side, not up and down. Trigger on before the door and off after passing the door, then trigger on as you come back, etc. overlapping by 50%.
The fine finish double orifice tips are designed for low pressure so test on a piece of cardboard and adjust pressure so tails just disappear. You still better forget about spraying in place unless you protect for overspray and sounds like you might need a little more experience before you attempt spraying in place. Perhaps make a little spray booth out of plastic in your garage.
Regarding spraying both sides, there are many ways to do it. I watched a video over and over and over from the Pivot-Pro website demonstrating both a pivot type table for spraying and a racking system for drying. I figured out measurements and then bought some tube steel and had my friend weld up this system. It worked fantastic.
If the doors are the six panel solid doors that haven't been primed, remove all hardware (knobs, hinges). Find a big enough area, probably your garage. Plastic off the entire garage, preferably a canvas tarp for the floor, or rosin paper. The overspray will make the plastic stick to your feet. Next, stand the doors up and place them at 90 degree angles to each other, leaving about an inch between the doors. Place a 1x2 across the top of the doors and tack nail or screw the 1x2 to the top of the doors. The first two doors will be a little wobbly, but as you continue to add more doors, you won't have to worry about them falling. This way you can spray all four sides at once. If you want to do the tops and bottoms, brush them out beforehand. Next do a quick sand just to get the burrs and splinters off the edges and corners. Use a vac, air compressor, or tack cloth to get the dust off. Now you're ready to spray. We spray one oil primer coat not thinned with a 411 fine finish tip. Let dry and then sand with 180 sponge pad. Clean doors again, then caulk panels using a damp rag to keep your finger clean. Let dry and then spray another primer coat. Usually don't have to sand again, but you may have to. Now you are ready for the topcoats. We spray two topcoats (oil) of Benjamin Moore satin Impervo or SW Pro Classic not thinned with a 411 fine tip. We get super smooth results with no runs every time. Takes a little practice. You might try practicing on the back of some closet doors to get your technique down to help eliminate any runs or skippers. Oh yeah, wear a respirator.
Comment from contributor A:
You probably finished the doors by now but in the future this may be of help. I stand all my doors up and spray with an HVLP system. There is very little overspray and it uses much less material. To prepare the doors we install 2 1-5/8" drywall screws about a 1/2" out. This keeps the doors of the ground and easier to sand. We make right angle brackets from scrap 3/8" plywood to hold the doors up and together. The brackets are simple and effective. Imagine a square - cut your plywood 10" long both ways. Make them 1/4" narrower than the doors.
Drill two holes on each end 1" then 2" from the edges. Screw one to the top of the door then stand the next door up and screw that one at a right angle. Proceed with the other continuing right angles. It may sound confusing until you attach the first one then it will come to you immediately. The reason you make the brackets narrower than the doors is to sand the top edge.