I have a question or 2 regarding finishing with a spray gun

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Forum topic by Mark posted 03-24-2011 01:23 AM 1042 views 0 times favorited 4 replies Add to Favorites Watch
View Mark's profile


1817 posts in 3513 days

03-24-2011 01:23 AM

Hey there gang, so first question I have is portioning poly and paint thinner. What is the mix ratio/percent for the best finish and at what PSI? And now I’ve been working on a few antiques and I’ve been wondering what kind of finish they used over 80 yrs ago? any idea ? :S Anyways thanks for your knowledge, i’ll keep it short :)

-- M.K.

4 replies so far

View GaryL's profile


1099 posts in 3069 days

#1 posted 03-24-2011 03:14 AM

There are alot of variables involved. Viscosity of the poly, tip size, conventional gun, HVLP, airless, etc.
Start with perhaps a 5% reduction and continue to thin until your getting a spray pattern and coverage that suits your needs.

-- Gary; Marysville, MI...Involve your children in your projects as much as possible, the return is priceless.

View patron's profile


13641 posts in 3580 days

#2 posted 03-24-2011 03:55 AM

most older finishes were nitrocellulose lacquer

rub some lacquer thinner
on a hidden spot to be sure

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View Gregn's profile


1642 posts in 3222 days

#3 posted 03-24-2011 04:58 AM

I thin my polyurethane by 15% according to what MinWax unofficially told me, meaning they don’t recommend thinning of their products. This has worked well for me.
Lacquer, shellac, oils, varnishes and waxes has been mostly my experience.

-- I don't make mistakes, I have great learning lessons, Greg

View gfadvm's profile


14940 posts in 2929 days

#4 posted 03-24-2011 05:25 AM

I spray MinWax Spar Urethane undiluted using the cheapest Home Depot gun at 50 psi.I was really surprised that it would spray but I get great results on vertical surfaces with no runs.You can lay a lot of material on in a hurry.I will apply subsequent coats while previous coats are still tacky.Dont ask what size orafice/tip thingy I have as I dont have a clue.Just got lucky by buying the cheap HD gun.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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