Sinew Curing!?

[Knotty]

Hello once again everyone!

I've been reading about Sinew backing alot lately.
However I didn't quite understand the time that sinew needs to cure (when applied with hide glue),
Some people say 2 weeks, other say a month..

I'd appreciate any advice and help on sinew backing!

Thanks 😉

[Pat B]

A lot depends on the relative humidity /H) in your area. In humid climates it takes longer than in dry, arid areas.
 I noticed when making sinew backed bows they looked dry after a few days. I wanted to be sure so I set the bow over the hot water heater in the utility room for a month for each of 3 courses. Whether I needed to let it dry that long or not, I don't know but I did and was satisfied with the results. 

[bradsmith2010]

yes I think there is a wide range of cure time that will work,,  I have a feeling the longer  cure times may be advantageous ,, I have rushed some jobs in a few weeks,, and they worked ok,, but i have a feeling the longer cured sinew might be more stable to work with in the tillering process,, not gaining weight or shifting tiller as much,, but I have no proof of that,,

[Knotty]

Alright guys, would it be better to let the sinew cure indoors or outdoors at full sun?

[bradsmith2010]

no full sun,, inside in the shade,,
full sun will melt your hide glue and you wont  have a sinew bow any more,,

[PatM]

Full sun is fine once the matrix seems more or less dry.  It can get very hot without melting then.

[Knotty]

Alright then, thank you everyone for the words of advice 😊

[bradsmith2010]

thanks Pat for clarifying ,, I put one in the sun one time and the glue started oozing out,,,, guess it wasn't dry enough yet, I am paranoid now

[PatM]

thanks Pat for clarifying ,, I put one in the sun one time and the glue started oozing out,,,, guess it wasn't dry enough yet, I am paranoid now

   I would think that the backing has to be at a certain moisture percentage  for that to happen, plus your full sun is likely hotter than mine.
  Sometimes I'll think I can squeeze a bit more  glue out when wrapping with inner tube and even doing that and placing it in full sun will yield no squeeze out.

   I've wondered if the warmth rather than just the drying effect might allow enhanced curing of the glue. Most chemical reactions or polymerization seem to happen better at increased temperatures. The molecules are more mobile then.

[bradsmith2010]

Im gonna try the inner tube on the next one,, I  have one roughed out now,,

[Pat B]

Doesn't an inner tube wrap impede the loss of moisture?

[PatM]

  It isn't  used during the actual drying period.

[Pat B]

So, once dry you wrap the sinewed bow with inner tube and set it in the sun to smooth out the sinew?

[PatM]

No. The sinew is already smooth due to the earlier process involving inner tube and heat while the glue is still fully wet.

 The additional time after the sinew is more or less dry is just based on the theory that warming the matrix will speed up the "curing" effect  rather than just the drying effect.
 

[mwosborn]

This time of year in my area the humidity is very high - dew points in the 60's and 70's.  Curing sinew is best done inside an air conditioned house IMO.

Many chemical reactions do occur more quickly at higher temperatures...however, they do not necessarily occur "better" at increased temperatures.  It kind of depends upon the goal of the reactions and what kind of reaction(s) is (are) taking place.  The "curing" of concrete for example does not occur "better" at higher temperatures.  I am not sure what reactions occur during the curing of sinew.  You have piqued my interest though - might have to do some reading on the "drying out of collagen" and the chemistry that takes place as it does dry out.