Newbie Spraying Polyurethane

[maroto]

Last week I try to make what I belived was an improvement on the finish of the guitars I build, so I switch from Nitro to Poly. I tried a test make it brushed but after several coats had to buffer it and the shine was lower than the actual raw material (by the way I`m in Costa Rica so a lot of the brands and products mentioned on some forums are not available here). Then I bought a little re-touch spray gun as working with guitars are very small areas, then after about 4 coats the poly showed some pinholes, I decided to let it rest and see what would happen. WRONG!! I checked the guitar 24hours later and it was full of blisters and bubbles; like the face of a pizza teenage guy. If anyone can help me on any advise on the technique it would be welcomed.

Edited October 28, 2008 by maroto

[DGW]

Last week I try to make what I belived was an improvement on the finish of the guitars I build, so I switch from Nitro to Poly. I tried a test make it brushed but after several coats had to buffer it and the shine was lower than the actual raw material (by the way I`m in Costa Rica so a lot of the brands and products mentioned on some forums are not available here). Then I bought a little re-touch spray gun as working with guitars are very small areas, then after about 4 coats the poly showed some pinholes, I decided to let it rest and see what would happen. WRONG!! I checked the guitar 24hours later and it was full of blisters and bubbles; like the face of a pizza teenage guy. If anyone can help me on any advise on the technique it would be welcomed.

What nozzle size and psi's are you running?

[ihocky2]

Also, what kind of poly, 2-part automotive poly or 1 part furniture poly? How thick are the coats you are spraying?

[kpcrash]

And the inevitable - what was on the wood before you applied the poly? Being in Costa Rica, I can't imagine the temperature was too low, however, the humidity may have played a factor as well.