sinew drying problem

Jura From Underhill · Post by **Jura From Underhill** » Thu Feb 11, 2016 7:06 am

Hei, I have problem with lengthwise cracking, which are creating during the sinew drying... I try to have high humidity at the start around 80%, and around 60% after sinew are transparent. And temperature around 20°C. How can I prevent to making this cracks?

mikekeswick · Post by **mikekeswick** » Thu Feb 11, 2016 8:42 am

It sounds like the sinew has dried too fast. Simply dry it slowly for the first week or so. I like about 50 R.h. and about 10 - 15 deg celcius.
You can fill the cracks with sinew and glue. They won't harm anything just visual apperance.

Adam Karpowicz · Post by **Adam Karpowicz** » Fri Feb 12, 2016 12:27 am

It seems the glue, holding the sinew fibers together, did not form a strong enough gelly and allowed the sinew to separate as it dried. Perhaps you can try using the glue at a higher concentration, so it would make a harder gel at 20 deg. Adding more fast-gelling glue, such as hide or tendon will help as well.

Also, the sinew may need to be shredded into finer strands, which are softer and do not resist the contraction of the layer when drying.

Adam

Jura From Underhill · Post by **Jura From Underhill** » Fri Feb 12, 2016 7:16 am

I use pure hide glue. But Its true then I used low concentration glue, just something around 25%. Today Im going to try make 3th layer with 30% glue. I will try it. Thanks!!!

Adam Karpowicz · Post by **Adam Karpowicz** » Fri Feb 12, 2016 1:34 pm

25% or even 20% should not cause such problems with hide glue. Perhaps make sure the bow is well cooled off for the glue to gel and the layer is not too thick.

The layer should dry with no help from fans, drafts etc. With forced drying, a top layer of crusty dried fibers may not allow the whole layer to compact uniformly as a whole and cracks and separations can be a problem.

Adam

Jura From Underhill · Post by **Jura From Underhill** » Fri Feb 12, 2016 7:24 pm

My temperature is 21-22°C, it can be lower, mayby outside. Yep, I had thick layer... so i save it for next time

Thanks for help Adam!!!