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I closed the box before Christmas. Ziricote and spruce from John Hall. I have been unable to do any further work because of bad weather here in Brisbane with floods/rain 100% humidity.
we have had a few dry days and I discovered cracks along the grain on the back - one from the end of the lower bout to the lower brace and another shorter one in the same spot on the other back plate.there is also a tiny separation of the top central seam on the lower bout but this seems to have been controlled by a cleat I put in as a precaution having had a similar problem in the past.
I would like your input on the best way to repair these. I guess its a good time to find the cracks. I have not done any sanding/finishing yet.
Thanks
Brian

Hi Brian...

Greetings from Cottage Grove Oregon!

I don't know if it's the best way to deal with cracks like those, but I use CA (super) glue. I seep the CA glue into the crack making sure the edges of it are in their original position. I've had good results this way.

TS Paxton

How much change in humidity did you experience?
You may need to re-humidify to close up those cracks BEFORE you do any gluing and clamping. Also, you won't want to use superglue on the top.

Kevin

over the past few weeks the humidity varied from 100% to 54 %
Today 64 %
I feel the top would close with increased humidity but one of the cracks on the back may need some form of fill.

This is painful to see this happen . You need to be aware of RH when you glue things up . I glue tops and backs below 50% rh Preferably at 40%. This allows the plates room to shrink without pulling themselves apart . If you are not sending a guitar and keeping it for yourself try and glue up in lower RH times .
If that isn't possible you can "cook" the top for an hour at 220 in an oven to help pull excess moisture out . Be sure to keep flipping it so it looses moisture on both sides evenly . You can rehydrate this and CA it . It may hold for you. Trust me, this happens to all of us once in a while .

thanks
the pictures are maybe a little deceptive.The box is already fully closed.
As the current RH is 60 % I do not think rehydration is an option as I imagine it would just re crack again as the humidity falls.
What is the best option for filling the crack from a cosmetic point of view.

correction current humidity 94 % at 23 degrees centigrade!
I cannot honestly say what the humidity was when I glued on the back but it was normal for here in the sub tropics.
we have had unprecedented rain for 4 weeks. Its only since it stopped that the cracks appeared
I feel that the ziricote is particularly brittle compared to the other few builds I have done with mahogany , cypress and rosewood, and granadillo.
Any suggestions on repair.

Brian,
Where are you located? How much of the year is the RH over 65%?

Kevin

Kevin, he's in Australia.
Hope the flooding there stops quickly and recedes for those folks.

Several years ago I learned a good lesson in humidity and humility when my daughters little parlor split wide open (it makes a sickening sound too, let me tell you). Here were a couple of threads I posted back then

http://www.kitguitarsforum.com/archives ... 73_0_2_0_C

http://acapella.harmony-central.com/sho ... tle-guitar

Since then I've repair a couple of other cracks. One of the neat tricks is to use very strong magnets on the inside and out to do the clamping - I bought a couple of the 1 inchers and simple counterbore a hole in the cauls for the magnets

http://www.stewmac.com/shop/Tools/Clamp ... xsr=9.4299

Note that the repair was done in 2008 and has been completely stable since (but we do really good humidity control on that and all my other guitars)