sinew backing

[Lee Lobbestael]

After applying a sinew backing with knox, how long should I let it dry before use?

[ChristopherO]

I leave mine for a month under a ceiling fan and skylights.  It depends on number of layers of sinew but the longer the better in our type of climate in the Midwest.  You will see a difference in the cast of the arrow in the winter as opposed to the summer.  Humid weather slows a sinewed back bow down.

[Pat B]

On the two sinew backed bows I built I had 3 courses of sinew and waited a month between each course. You probably don't need to leave it that long though. The ancient Chinese would wait 10 years before stressing a sinew backed horn bow.

[Art B]

I tested one after only five days of appling the sinew and the reflex came back the very next day. But I brush on several coats of spar varnish and let that dry good before sinewing. That helps keep moisture from entering the wood from the wet sinew and glue. I use the Tite-bond glue and it will adhere to the scuffed up varnish better than the wood itself I believe.

Can't figure that Chinese method out Pat. Once sinew cures it won't draw down anymore. Say it takes sinew six months to a year to cure and you're using year old sinew to begin with to back your bow then once everything is dry you're good to go IMO. Now if you're using "just dried stuff" then waiting a longer period of time may be wise.

ART B

[yewsage]

is the varnish a good idea?  do you then size the back OVER the varnish?  i thought the idea was this:  hide glue on the back, and hide glue on the sinew.  that way glue sticks to glue.

[Art B]

Yewsage, I think you missed the part where I only use the Tite-bond glue for sinew backed bows. ART

[Brent Hill]

Thanks Art B, I'm about to sinew an osage flatbow bow with tb3 and was wondering how to prep the osage before applying the sinew and tb3.  Any other tips will be appreciated.  I've got the osage floor tillered but I wanted to put my 1st layer of sinew down from the handle up to 5-6 inches from the tip before I start the real tillering for a little more insurance against breakage.   After I get the bow closer to my desired weight, I planned on then putting on  layer 2 and 3 oof sinew.  I know that this will add to the poundage but I planned on doing my final tweaking after that point.  Any suggestions ??  Sorry to hijack.

[yewsage]

sorry, i did, you're right...

[Art B]

Brent, just try to keep limb length short and narrow. You can trap the sides of your limbs to help narrow the back if need be. Since sinew and glue add additional limb weight just use enough to get the job done to prevent weigth gain/loss due to changing enviroments.

IMO, the Tite-bond glue will adhere better to a scuffed up varnish surface than the oily osage wood itself. At least I've never had a problem doing it that way. Just clean you limbs with acetone or other solvent before varnishing.

I use leg sinew instead of back sinew with this type of glue. Backstrap is just to course and oily and doesn't work very well with Tite-bond glue. At least from my expericence. Perhaps degreasing backstrap sinew might work.

I like to go ahead and get a bow shooting and then set the limbs back before adding the sinew. The freasher the sinew the better in my opinion with this type of glue. Again, IMO, old sinew that's been cured has all ready shrunk down and will add little or no futher tension to the limbs once dry. Fresh sinew (but dry), I belive will continue to shrink, aidding or adding to reflex.

A good idea is to place a balance mark center of the bow's handle so that you can work the sinew down to balance the limb's weight back out encase you happen to apply more sinew/glue to one limb than the other. Hope that helped. ART

[Brent Hill]

Thanks for the info.  How narrow do you make the working limbs versus the tips.  

Do you scuff the varnish with rough sandpaper, or hacksaw?

Thank you very much.

[Art B]

You just want to knock the gloss off the varnish without sanding through it. I use a piece of well worn 180 or 220 grit paper for that.

Type of wood, design and so forth will determine your limb width. But you can still narrow the width of the bow's back by trapping. As a general rule, limbs tips of about 1/2" width is always a good place to start IMO. ART