Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Sealing wood -- is it necessary -- not in my opinion
By:Joe Greenley
Date: 8/18/1998, 2:49 pm

I have to disagree with the assumption that there is a "need" to seal the wood before applying glass.

I am confident that the only reason that manufacturers recommend sealing the bare wood is to simplify the glassing process for those who may not have much experience with these materials. For example, it is much easier to "starve" the glass on an unsealed boat than on one where the glass is applied to sealed wood. It is also much more common to run into "off-gassing" with its inherent "bubbles in the glass" problems with wood that has not been sealed.

However, if one takes the time to ensure that there is enough epoxy being applied to thoroughly saturate the cloth (this may require babysitting the project for an hour or two) and that the workroom temperature is falling (or at least constant) and then SQEEGEE THE EXCESS OFF at the appropriate state of cure, then these problems can be totally eliminated.

I feel that by allowing the epoxy to soak into the wood as much as it wants, and not wiping it off prematurely, results in a hull with greater impact resistance than one with a thinner, surface-only coat (drop a marble from varying heights onto wood that epoxy has been allowed to soak into and onto another that has only a thin surface coat to get a feel for this). Granted, a little more weight may be added to the hull at this point, but the impact resistance is well worth it.

Another advantage to allowing the epoxy to soak into the wood is that, in the event of a scratch that does go through the glass, the added depth of epoxy penetration will deter and slow water migration through the wood.

I have used this glassing technique for years now and am totally confident of its validity and the ability of almost anyone to master this method after only one or two practice sessions on TEST PIECES.

Messages In This Thread

Sealing wood -- is it necessary -- not in my opinion
Joe Greenley -- 8/18/1998, 2:49 pm
Re: Sealing wood -- is it necessary -- not in my opinion
jim champoux -- 8/18/1998, 3:11 pm