Sinew back issue

[High-Desert]

I just sinew back my first horn bow last weekend. After a few days of drying, a small section about 3/4" long seperated from the layer below. It's a very small gap, maybe a 1/16" lifted up. I was planning on putting the last ounce of sinew on this coming weekend. I think I have a plan to fix it, but before I do anything, I was curious what you all have to recommend before I touch it. Thanks

Eric

[loon]

That kinda sounds like you should've been pulling the bow into reflex more while it was drying

Would wrapping with sinew help? I wrapped my horn bow with sinew in a part where the sinew was damaged and it lifted when I braced the bow, though :\

[PEARL DRUMS]

Warm it back up and stick it down.

[High-Desert]

I don't want to put anymore reflex into it. It's already a half circle. I haven't wrapped it yet. Was waiting to get the second sinew session on before I wrap the handle. I guess I should add that it pulled up after I had wrapped it with cloth and let it gel too much and it stuck to the cloth wrap in that area, and when I unwrapped it, it pulled that area up.

Eric

[High-Desert]

Should I apply direct heat, or wrap it, then apply heat?

[PEARL DRUMS]

Warm up a spot of glue, sway a heat gun over the area lightly warming it. Then put glue in the gap and on top. It should soften the sinew up and allow you to push it down flat and mesh it back together with the under layer. Maybe wrap it for a few hours to be sure it stays down as it cools and dries.

[Aaron H]

I guess I should add that it pulled up after I had wrapped it with cloth and let it gel too much and it stuck to the cloth wrap in that area, and when I unwrapped it, it pulled that area up.

Eric

For future reference, you can mist the cloth with water if you let the sinew/glue get too gelled up, and the cloth will separate from the sinew/glue without pulling your matrix apart.   Learned that from PatM's sinew build along, thanks Pat! 

[High-Desert]

Great! I'll give that a shot. The sinew article is what I read but I was unwrapping too fast and it only stuck in that area. Thanks guys for the help

Eric

[wizardgoat]

You can drop some thin super glue in the void and clamp it as well.

[High-Desert]

I would have never thought of that. I'll give that a shot if I can't get this to hold. Thanks s again everyone.

Eric

[mikekeswick]

The way to avoid it is to apply sinew , let it gel THEN pull it in more reflex. This places the sinew under compression and the gelled glue will hold it  whilst reflexing.
If you do this sinew will never come off the core.
I would recommend against wrapping sinewed hornbow limbs. It may have some merit on wood/sinew bows because any wooden bow can't bend enough to start straining the sinew fully and a lower amount of glue isn't all that important but on a hornbow the glue is very important and you should be using about the same weight of glue as sinew. You also want the back to be flat and this is not going to happen if you wrap the limbs.
As to how to fix warm the area, heat 10% glue with a touch of alcohol added (to improve wetting),immerse the affected section in your glue and flex the limb back and forth until no more bubbles come out. Then reflex the bow by a few inches (important) and wrap the area to ensure good contact with the underlying sinew. Remove the wrapping after the glue has gelled.
Don't worry about adding extra reflex as you will be removing it in the first few stages of tillering. Much more important that your sinew laters hold up than worrying about a little extra reflex.
good luck.

[High-Desert]

Thanks mikekeswick! That makes perfect sense.

[PEARL DRUMS]

I pull the blank into reflex before I add any sinew. I suppose in the end the results are the same as Mikes.