Thinning Sealer for Tropical Woods

A finisher finds that thinning the sealer eliminates his bubble problem. January 18, 2011

I have a spray booth and have received 3 bubinga gun stocks to finish. I am using ML Campbell exotic wood sealer and Euro X Wet Look 2k as the topcoat. I used a small piece of oak and mahogany as test pieces. I sprayed the sealer as suggested and it says to dry 2-3 hours before next coat. The second coat created air bubbles from the pores of the wood. More from the oak. Any help?

Forum Responses
(Finishing Forum)
From contributor R:
Did you reduce the Euro X wet look? In most cases you will want to thin the material with 10-20% Euro Reducer, but not sure about your conditions or equipment. Bubbling is generally caused by open grain, hot conditions, wrong thinner or amount, or getting on top too fast with another coat and causing solvent entrapment. Your best bet is to thin it a bit more with Euro Reducer and to wait for each coat to dry completely before your next coat. You can just mix up what you need each time. Hope that helps.

From the original questioner:
Thank you. I got the bubbles in the sealer and have not put on the finish. Should I sand down the sealer as a pore filler? Everything I got for the system is from my dealer.

From contributor R:
Yes, you can sand down the sealer, but it does not have tons of solids for fill. Thin the sealer down a little more and then start building with the topcoat. Try to sand flat without burning through on the coats. Probably just need to take more dry time and you should be good. If you are going to buff the stocks when you are done, just let them cure for 3+ days to make sure you don't get any shrink back if you are going for a filled look.

From contributor L:
Grab a piece of ipe or something that has a similar grain structure and an oily surface. If I recall correctly, bubinga does not have an open pore structure like oak. The best thing you could do is get a bubinga sample and spray that as your test.

From the original questioner:
Thanks for the reply guys. The instructions stated to not thin the sealer, but I got brave and thinned, then sprayed a new sample, and this worked. I have also sprayed the Euro-X thinned and it is looking good.