Preventing Bubbles from Forming in your Finish Coats

by Alan Noel

Whether you’re a hobbyist or a pro, brushing on an even coat of bubble-free oil- or water-based varnish
is often a very frustrating task. Sometimes bubbles even appear mysteriously while the finish is drying, even though they weren’t visible during the application process.

Here are six tips I’ve found to help eliminate those pesky tiny bubbles:

1. Never shake the finish. Shaking the container will cause bubbles. Always stir the finish in the can.
2. Be sure to apply the finish in the direction of the grain whenever possible.
3. Always use a good quality brush. This is the most important part of the process. A high
   quality natural bristle brush should be used for oil based varnishes and the best for water based
   finishes are brushes having synthetic bristles.
4. After brushing on a coat of finish, use a different dry brush of the same type and gently brush the
   finish holding the brush at a 45 degree angle to remove any bubbles that are in the finish.
5. Remember that two light coats are better than one thick one. Laying it on too thick
   will promote skimming of the finish. Trapped thinners will then force their way towards the surface creating
   bubbles.
6. Never attempt to finish any surface unless you are sure the wood is completely dry and ready
   for finishing. Trapped moisture can cause bubbles to appear long after the lights have been turned off.

Visit Highland Woodworking’s WoodNews Online Archives for more tips and information.