Crack in soundboard

[Ron Daves]

I am building my #1 guitar. I am in the southern California desert with a very low humidity.
My guitar has developed a crack about 1/2 inch from the fretboard between the edge of the upper bout and the rosette. It is very tight, but can be manipulated up and down a small amount. I did a dumb thing early in the building process and caused the crack. I glued it back together with PVA glue and sanded it out fine. But I have had to keep it outside of the humidified box that I keep it in while I had clamps on it.
Questions:
How do I clean the glue out of this tight crack?
What do I use to re-glue the crack?
Any other advice?

[Steve]

Ron,

I used to build guitars in Albuquerque (low humidity) before moving to Austin (high humidity). I had a crack develop on an Albuquerque guitar in the lower bout but the fix is the same. If there is no gap in the crack then brace it from underneath with a small patch. Remember to orient the patch 90 degress to the grain of the soundboard. Use hide glue or white luthiers glue (I use the latter). I am not familiar with PVA. Is it heat or steam sensitive? Souble in alcohol or some other solvent? Try to clean up with those then use the glues I recommended, if possible. If you have magnets (neodymium are best) use those for the clamping as they are easier to position. Best of luck.

Steve

[Ron Daves]

Steve
Thanks for the input. The glue I am using is white luthier's glue from LMI. It is a PV glue, according to the label, I added the "A" on the end, perhaps incorrectly. I have ordered hide glue and am waiting for a delivery. I like the idea of magnets. They must be quite powerful. I have a couple magnets that I use for welding. I will see if I can clean them up and get them to work. I have a cross-grain splint prepared and will be gluing it in as soon as I get the Hide glue. I plan on squeezing some hide glue into the crack, then putting the splint in place. One person I talked to recommended putting splints across the crack at 3/4-inch intervals instead of a solid piece. What do you think? This splint is about .085 thousandths thick. What are your thoughts on that?

[Nick Anthony]

hey ...hope this helps..
i've been doing guitar repairs my whole life and have never been pleased with the results gained from cleating cracks (cross grain patches). depending on the finish used (laquer or a catalyzed poly etc) i'd probably use a CA glue. CA glues are not very forgiving but are an awesome tool when you get used to them. i use them even on laquer finishes..with a couple of different techniques you can even spot finish over them without getting blend lines. wick thin ca glue into the crack and kick it w/ an accelerator. using a scraper or razor blade w/ a burnished edge clean up the glue being as careful as possible..scuff w/ 220 and shoot a thin coat or two of shellac on the scuffed area...let that cure for 2 days at least...then w/ the finish you origionally used...the shellac covers the ca glue and you will show no blend lines.

good luck
nick