Re-hydrated crack too tight to get glue in ...

[simonm]

Assume you have a guitar with a cracked top due to humidity issues (winter, central heating, icy weather, the white stuff on the ground etc). After humidifying for a few days the crack is almost visible and as tight as a tight thing. Do you have a strategy for getting glue in? Would cleating alone be enough? Do you ever put some hhg into the crack before humidifying?

I have had two guitar with top cracks due to drops in humidity (20% in a climate where 50%-70%-ish is the norm). In both cases rehydration closed the gaps (initially 1mm-2mm) so tight that even knowing where the crack is it is hard to find. One was a 1980's Spanish for a well know maker in my own place. The other was one of my creations and at a customers house. Jan/Feb seems to be the peak humidity caused top crack time based on a massive sample of 2 guitars.

My attempt at gluing involved rubbing in fairly thin hhg from the top while manipulating the top with the other hand through the sound hole. To complicated matters the crack is very close to the centre fan brace so at one end next to no space for cleats.

Any thoughts?

[Allen]

I've only had to do one of these type of repairs, and that was on a tenor uke.

I used thinned out HHG and massaged it into the crack from the top and manupulated the soundboard as best I could from underneath. Could just barely reach it through the sound hole. Once I was certain that some of the glue had penetrated through I added some full strenght glue and continued in the hope that it would get pulled in as well.

Seemed to work and repair was invisible.

[simso]

On a nice tight crack that has closed up from humidying, I have two ways of doing it.

First put a small scissor jack inside and re-open the crack, pack it with glue and then let remove the jack, it will pull up just fine.

If using a jack and it does not open up enough, I apply titebond to the surface of the crack and use air pressure 15 psi to push it in, clean up and allow to dry

Steve

[simonm]

Thanks guys.

The sissor jack is a new concept for me. Had a look at it over on stewmac. I have to admit I would be quite nervous cranking that up inside a lightly build guitar for the first time. I do have stewmac voucher at the moment. Hmmm

Simon

[simso]

On a nice tight crack that has closed up from humidying, I have two ways of doing it.

First put a small scissor jack inside and re-open the crack, pack it with glue and then let remove the jack, it will pull up just fine.

If using a jack and it does not open up enough, I apply titebond to the surface of the crack and use air pressure 15 psi to push it in, clean up and allow to dry

Steve

Had to glue a split laminate up the other day, heres a link showing how I use the air pressure trick.

Steve

http://mirwa.com.au/HTS_Repair_Split_Laminate.html

[simonm]

Thanks Steve.

Very interesting method. Thanks for linking it in here.