sparying Polyurethane?

[jaustin]

Can you spray Polyurethane using hvlp?

 

[jeff...]

Since you didn't get any response, I'll answer - YES polyurethane can be sprayed, actually with quite good results too. I thin it apporx 50/50 with mineral spirits, load the gun and shoot a mist coat with the gun adjusted to widest pattern I can get. I think the trick is to build up several thin coats. If you think the coat is too thick chances are it's too thick. Build up real thin coats and it should work out well.

Recently there was a lot of good discussion about Polyurethane in this thread:
http://www.ncwoodworker.net/forums/showthread.php?t=5494&highlight=Polyurethane

Personally I like polyurethane finish, it's tough and easy to clean and repair. Although some folks are dead set against it as a furniture finish. To each his own, that's why there are some many different types of finishes out there. Find what finish works best for you and run with it.

Thanks

 

[Travis Porter]

I thought that was what you would do, but I have never sprayed it myself. Just done the brushing with it, which I do not do very well.

 

[Howard Acheson]

Can you spray Polyurethane using hvlp?

Yes. You may have to thin depending on your equipment.

The problem with any oil based finish is that it is slow drying. The overspray stays liquid and the wet mist gets all over everything in the shop or area. You end up with a crust on every surface unless you have a spray booth or spray outside.

If you try to spray outdoors, be sure the temperature is above 60 degrees. At lower temperatures, the finish will have a significant tendency to run and sag and it will take a very long time to dry.

 

[edcox]

I use a water based poly in my HVLP system and it works great. No need to thin with the right tip. I like the fact that flows out smoothly, dries clear, no solvents and water clean-up. I've been getting mine at Lowes but am going to try some from Target coatings on my next project. One caveat - clean the gun immediately after use and I mean immediately. If the poly dries in the gun it is a lot of work to clean it out. I just fill the cup with warn water and a couple of drops of dishwashing detergent and spray for about 30 seconds, this seems to do the trick.

 

[jeff...]

I'm thinking I may give water based poly a try, I've already seal coated with oil based poly and it's dry so I'm thinking I might try water based over top the oil based, shouldn't be a problem. I'm just not into water on bare wood, I even kinda freakout about cleaning up glue squeeze out with a rag and water.

Your also right about cleaning the gun ASAP, I put a few oz of acetone into the gun and spray into a paper shopping bag for about 30 sec, then dispose of the bag ASAP. If I'm not going to use the gun for a while I'll disassemble the gun and let the parts soak in a glass of acetone for a few hours then wipe clean and reassemble, seems to work well so far.

Thanks for the water base poly tips :icon_thum I'm going to give it a try.