Bubbles in the Finish

< back to all technical articles

NEED BUBBLE PHOTO

Bubbles are a common problem with high viscosity rod finishes, such as Flex Coat. Some of the bubbles are created when you mix Part A and Part B. Some come from air trapped in the bristles of the brush. Others work their way up from the thread after the finish is applied. There is no 100% foolproof way of getting rid of bubbles in these thick rod finishes.

The way that I mix these thick finishes is in a plastic measuring cup stirring very slowly using the tapered end of a previously used disposable brush. Stirring slowly, and using the tapered end of the brush will lessen the amount of bubbles introduced into the mixture. Next I pour the finish into a well washed portion tray from frozen food entrees. You must be sure it is absolutely clean. You will not want to work directly out of the measuring cup, as the depth of the finish in the cup will keep the bubbles from coming to the surface and escaping. You will need to pour the mixed finish onto a flat surface, a square of aluminum foil works quite well. The thinner the layer, the easier it is for bubbles to escape. I use a small plastic frozen entree dish to work out of, and I use the same little portion tray for many batches of finish, basically until it is too full to use anymore. Allow the finish to sit for a few minutes before applying to allow the existing bubbles to escape. Trim the bristles of the brush back to a length of 1/4" approximately. Apply finish slowly, as rushing the process will also introduce bubbles. I do not recommend trying to apply the finish while the rod is attached to the drying motor. What I use is an old wrapping fixture that I no longer use for wrapping. This lets me rotate the rod at the speed that I need, being able to stop, back up and get the finish neatly under guide feet, etc. These are all things that cannot be done while hooked up to a gear reduction finishing motor.

After applying the finish I place the rod in my drying motor and rotate for 4 hours, most finish manufacturers say less is needed, but I would prefer to be safe, so I use 4 hours. While the rod is turning, apply heat, with a, low, clean flame, such as from an alcohol lamp. Do not use a butane cigarette lighter, unless you like the effect that soot leaves all over your nice pretty new wrap. You may use propane, as I do but this is a high, hot flame, and you must be very careful not to overheat the finish. Doing so with either a propane torch or even the comparatively "cool flame" from an alcohol lamp can result in even more "bubbles" which are actually created by the finish starting to "roast. or boil" Just "lick" the finish with the flame, and you'll see the bubbles rise to the top and break. Heat does two things: 1. It momentarily thins Flex Coat enough to allow bubbles to escape; 2. It expands the air in the bubbles so that they'll burst. This covers most problems with miniature bubbles, just keep checking and be careful not to overdo the heat.