Main Discussion Area > Bows
Bubbles in sinew backing?
Marin:
--- Quote from: superdav95 on June 12, 2023, 10:04:21 am ---I can’t see the bubbles you speak of in the pics but so long as they are not air bubbles I would say they are more asthetic and shouldn’t be a performance issue. How are you laying your sinew down? Do you lay down smaller shorter sections of bundles or do you lay down longer more measured layers? In the past When I’ve laid several smaller bundles of sinew I noticed irregularities in the surface of my backing that I believe were the some of the feathered ends of the bundles curling up or twisting underneath other bundles. Hard to know for certain but a possibility. It functioned fine but this may be the same thing you’ve seen in yours. I now since have switched my sinew method to longer more measured layers. FWIW
--- End quote ---
I would say these were more “medium” sized bundles, around 5 or 6 inches.
I cut the ends of my bundles to square them off and avoid the “feathery ends” from doing weird stuff, so I’m not sure if it’s that.
Marin:
Also I should note that these bubbles are so small I don’t hear any popping or cracking when I push along these areas.
Marin:
I'll attach some more photos of a different section of the bow where it is more noticeable. I tired in two different light settings. The loghter colored parts of hte backing is where the air bubbles I am talking about are. Some seem to be on the surface while others appear a bit deeper. In some cases the "air bubble just seems to be where the glue retracted without taking the sinew with it, bhich makes me wonder if maybe my glue isn't hot enough or wrong mixture or something.
Marin:
I should also note, these bubbles really only appear after the glue begins to harden. I'm planning on sanding the back a bit and thin layer of glue so if the bubbles really are that shallow, I hope this help fill them in.
superdav95:
Looks to me that this may be an issue only with your last layer. Are you doing one solid layer or several layers and letting each dry well before the next layer. I like to scuff between layer personally and depending on the bow or project aim I’ll do 2 or 3 layers letting each dry well. I put a good layer of glue prior to next layer. It could be you’ve starved it of glue between layers perhaps??? Just a theory…. You sinew looks pretty clean to me this being said. I don’t foresee any performance issues. Here’s a couple pics of my latest sinew. It’s been drying for a few months now just almost ready to start going on it. It’s ready and dry now but I’m giving it lots of extra time. You’ll see that it has some lighter coloured inclusions and not totally amber in Color. This is normal for sinew. Help this helps.
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