Sinew backing

[Jjpso]

Hello there! Im in the process of building a osage Sinew backing bow. Some years ago i remember a post or build along, of some one explaining a technique to get a more clean back, and to squezee the excess glue, but cant find that post! Does anyone remember who posted it?
Thanks

[Eric Krewson]

I don't remember the post but if you neatly wrap the wet sinew tightly with saran wrap it will smooth it out and get rid of the usual stringy look, you can then sand to look as smooth as fiberglass.

[superdav95]

I’m not sure if you are talking about my post a while back or not but if you are here is the basic method,   

Prep you sinew.  Comb and separate the fibers how you normally would or prefer by pounding or twisting depending on if using back sinew or leg sinew.  Once in fairly small fibers separate into piles of short med and long lengths.  Then weight it into separate bundles depending on how you want to lay down your sinew wether in a stagger brick pattern or in overlapping wider strips. 

Prep the back of your bow.   Many schools of thought here but for Osage in particular I would wash well with alcohol after scuffing with 60-80 grit paper or use a fine toothed hacksaw blade to make tiny grooves the length of the bow where sinew will go. 


Sizing coats is often overlooked with sinew backing.  There is a belief that it’s only necessary for glueing horn laminate but this is not the case in my opinion.   Especially with a wood like Osage.  When you wipe with alcohol you will notice color come off.  There are oils with this that can make the sinew less adhered.  Proper size coats of thin hide glue can make the difference often with backing with sinew.  I use 5-10% glue meaning if one was to want a 5% concentration you would for example take 5grams of dried hide glue and mix 95grams water then heat.  On a horn laminated bow this coat would be 12-15 times allow to dry in between.  But for sinew backing sizing I do about 3-5 coats heating or warming the back of the bow slightly with each coat. 

I lay wider premeasured strips for each limb that have been soaked in 25-30% glue that have been allowed to gel slightly on a board or a piece of glass prior to laying down.  A generous coat of glue brushed on prior also to laying down.  The strips method of laying sinew does help me to get perfectly aligned fibers combed and shaped prior too.  If the staggered method is your choice just overlap a little at each stagger.  I’ve had good results with both methods. 

After the sinew layer is down and allowed to fully gel up to the touch but not dry I wrap with horse leg wrap.  I leave this on overnight and then remove.  It leaves a smooth clean finish.  I’m sure the Curran wrap method work also but I prefer the breathable wrap.  It’s very thin and has a slight elasticity to it to compress it down well.  The problem I down with the Curran wrap sometimes was trapped moisture.   I’ve also tried ace bandage method wrapped as tight as I can and then putting it out in the sun or heat gun on low setting for about 10mins or so or until I see glue oozing out.  I will use more then normal glue knowing it will ooze out a bit the excess.   I didn’t like this method and found it quite messy and a pain to get the bandage off. 

Hope this helps.  Message me if you would like more clarification.  If you look back on some of my posts you will find more details too. 

[bassman211]

  Some claim that  there is no need to sinew back a longer bow...for me 60 inches and longer, but there is a real advantage  to using it on short bows....38 to 52 inches in my experience.  The above ways explained above work fine for smoothing it out on the back.