Glass limb cracks

[Dale in Pa]

To start,just a little history. I've been making bows for over 15 yrs,mostly for myself and friends and a few for trades and sale. I've made over 100 bows and in the last couple years have started to have problems with splits in the belly glass.They start near the fades and continue out.

The first RD longbow to do this started to split about 9months after I made it.I shot it a lot and killed a couple deer with it in the fall and the following spring I noticed the splits started.They continued to increase until the longest one on the bottom limb was probably 20" long and top limb about 16".

Around this time I started to make 3 pc TD longbows and have had several of them split as well.They start pretty much at the limb butts and continue down the limb.So far the worst ones have cracked maybe 8" or so. Perhaps split isn't the right word.If these were in colored glass they would be hardly visible.You can just barely feel it with your fingernails,but can see it goes all the way through the glass lam.

This has only happened since I started to buy glass from 3R. Has anyone else had this problem with there glass? It's supposed to be clear Bo-Tuff.Is it possible they got glass with no scrim mixed in.The glass has been exceptionally clear.Thoughts and ideas please!

[Bow-n-Head]

Dale; Sand (thin) a sample piece of glass a little at a time.  The scrim should show up.  Ray

[kennym]

Just a thought, is your finish waterproof? Could the lams pick up moisture over time and crack it from swelling?

I use UL on all my d/r longbows without a single prob yet.

On glass that is not glued on the bow, hold it up to a bright light and you can see the scrim, lines across the glass about 1/16" apart.

[Walt Francis]

I got my first crack in the glass, next to the riser overlay, during final polishing Sundy.  I almost felt as bad about it as having an osage bow break...almost but not quite as much.  I could have moisture on mine, I was using denatured alcohol while wet sanding when I noticed the crack.

[Dale in Pa]

Don't have anymore of the 3R glass to check. I think my finish is waterproof though.It's a Dupont automotive clearcoat. Finished quite a few  other bows with it with no problems.

Kenny,what's the UL mean?

[Dale in Pa]

Never mind Kenny, I looked and found out it's glass w/o scrim.

Walt, broke my heart too,to see these cracks develop over time over some beautiful veneers.

[kennym]

3R catalog doesn't say, but I'm betting by their price it is ul.

I hope it isn't the clearcoat, I just finished one with that!