WHere's Waldo

[Dean May]

You recommend using the thin CA to coat the crack and then using an
accelerator to cure the CA. Then you recommend using thick CA to fill the
crack. What kind of bond is formed between the cured thin CA and the thick
CA? Thinking along the epoxy line, the thick CA should be applied before the
thin CA cures - that way all will bond into a single unit - the gap-filling
thick stuff, and the stuff that soaked into the walls of the crack.

I'm speculating that CA might be like epoxy in that a chemical bond (formed
before cure) will be a strong bond. But if the initial thin CA application
is allowed to cure - and the surface is not coarse-sanded for adhesion - and
the thick stuff is applied, you may not get a good bond - and we are talking
about a tension stress here.

Just a thought.

Terry Farrell

Hey Terry,

I am pretty convinced that what the thin CA glue does is stabilize the wood.
It wicks deep into the wood and when it sets up, the wood's cellular
structure acts as a matrix, and the glue makes it all incredibly solid.

I applied some CA glue to the butt end of the jack the other day, right
below the birdseye, where the endgrain is exposed. I've done this before to
tighten up a loose pin.  I only applied two to three drops, and in no time I
saw splotches all the way down the jack where the CA glue had wicked. Try it
yourself, see how far that stuff will wick into the wood.

Based on my experience with CA glue I really don't think adding the thick
stuff to the crack will do much. It only makes us feel better to know the
crack is filled up. The real strength is in the matrix of the wood.

Dean
Dean May             cell 812.239.3359
PianoRebuilders.com   812.235.5272
Terre Haute IN  47802