Spraying Polyurethane

  • Advertise with us

« back to Finishing forum

Forum topic by dbw posted 12-25-2015 10:39 PM 570 views 0 times favorited 6 replies Add to Favorites Watch
View dbw's profile


143 posts in 1057 days

12-25-2015 10:39 PM

Topic tags/keywords: finishing spraying polyurethane

I have a quick question: How hard is it to spray Polyurethane? I am getting brush marks even though I am using a foam applicator. I have a HVLP gun which was given to me years ago and it’s sitting new in a box. I’d like to use it and I’d like some pointers. Thanks.

-- measure 3 times, cut once

6 replies so far

View Tennessee's profile


2410 posts in 1935 days

#1 posted 12-25-2015 10:50 PM

Set up the gun for about 40 lbs. max. Follow directions on the can for thinning the poly, if needed. (Some polyurethane’s don’t need thinning, but if it is a bit colder you might want to consider thinning a bit.)

I always set my nozzle pattern vertical, so when I go across the top it is a vertical wall of poly, not a line of poly I am laying down. Remember that almost all vertical wood surfaces will run if you stop the gun anywhere and happen to apply a bit too much.

You spray it on until you just get a full wet coat, absolutely no more. One big issue with poly is the tendency to have that cloud overspray that always seems to be just around the area you just sprayed. HVLP guns help a lot with this, (Low Pressure does not push the liquid so far into the air), but it will still be there a bit. The wet coat helps. Poly dries much slower than lacquer, so you will have to wait quite a while between coats.

I clean my guns with lacquer thinner, other people use paint thinner.

You may want to put on two-three coats.

Biggest hint: Test spray on something you don’t care about, even if it is a cardboard box. See how much it takes to lay a wet coat before you spray the actual project. Spray vertical to see worst case scenario. Practice keeping the hose out of the way. You’ll do fine.

-- Paul, Tennessee,

View dbw's profile


143 posts in 1057 days

#2 posted 12-25-2015 11:01 PM

how does one handle the edges of boards, e.g., lids, etc.?

-- measure 3 times, cut once

View AlaskaGuy's profile


2396 posts in 1729 days

#3 posted 12-25-2015 11:56 PM

If it’s an oil base poly how you going to handle the sticky over spray that get all over the shop.

-- Alaskan's for Global warming!

View Tennessee's profile


2410 posts in 1935 days

#4 posted 12-26-2015 01:28 AM

Edges, etc., I used to have to sometimes spray two times to make the coverage, but mostly could support things on support blocks to get it done. Little innovation usually goes a long ways if you think in terms of what you have to cover with the gun, and what you can get away with by hand.

As far as the overspray, I keep a roll of that cheap plastic folded sheeting that the interior housing spray guys use to cover things quickly when they spray walls and ceilings. It’s quick and easy to form a tent that will keep most of the overspray in the area. Usually I just hung it from the ceiling, or sometimes stapled it up. Only takes a few staples to hold up the lightweight plastic.
Or, if you get a good day, and you develop a way to move it out, spray it, move it back in so bugs don’t get into the finish. Tabletop might be too big for that.

-- Paul, Tennessee,

View Ger21's profile


1047 posts in 2551 days

#5 posted 12-26-2015 01:50 PM

If it s an oil base poly how you going to handle the sticky over spray that get all over the shop.

- AlaskaGuy

I’ve sprayed poly before, and it makes everything sticky.

-- Gerry,

View jim C's profile

jim C

1467 posts in 2519 days

#6 posted 12-26-2015 02:08 PM

I’ve used the minwax water based spray gloss on oak cabinet doors and they came out like glass! It dries quickly. I would never go back.

-- When I was a boy, I was told "anyone can be President", now I'm beginning to believe it!

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics