QUESTION: What are the possible causes of delaminations, air bubbles or cloudy spots in the limbs of my traditional bow?
ANSWER: These problems are caused by not having a good Bo-Tuff/epoxy/wood bond.
The usual culprit is one of, or a combination of, these three things:
First, some kind of contamination on your laminations. This can be either surface moisture, using a solvent that isn’t pure, or dust. Your wood laminations can pick up moisture from the air. This will interfere with the epoxy. Lay out your wood laminations in your pre-heated heat box for about 30 minutes. Let them return to room temperature before laminating. We don’t recommend using solvents, just use a stiff bristle brush to clean the laminations.
Second, insufficient pressure. I’m not referring to the 60 psi in your hose, that is sufficient. If your top and bottom form are too far apart, the air hose rounds up more than it should. The more your hose rounds up, the less it wants to bend and the less it will give you good pressure. If you are consistently having issues in bending part of your limb, such as the reflex of your recurve or the fadeout of your longbow riser, this may be your problem. To correct this, add some shim material between the hose and the top part of the mold to take up the extra room. Your hose won’t have to round up as much.
Third, dry spots. Make sure you use plenty of epoxy. You can have a “sufficient” glue line, but while you are spreading epoxy on the other laminations, the glue can seep into the wood, creating a dry spot. Before putting mating laminations together, check them under a light. They should be shiny everywhere. Look specifically for those dry spots. Dry spots will have a dull appearance. Apply more epoxy to these dull looking areas.