very important fiberglass question

[Mike Mecredy]

Has any body every seen fiberglass just simply develop long cracks, while simply setting on the rack, less than a year old, very little use?  Curious.

[kennym]

No , you have that happen ?

[Mike Mecredy]

I had a customer send one back that way.  Otherwise pristine. He said he took it off the shelf to shoot it after it sat for a long time, and it had the cracks.  I'm at a total loss.  1300 plus bows and I never seen it before.

Also it was light draw weight too, just fraction  under 40# @ 28"  and 68" long.  Not a lot of stress on those limbs.

[kennym]

Sorry I thought you meant glass in a stack. I've heard of bows getting longitudinal cracks and think it has to do with the lams being dry and the finish letting enough moisture in to swell the wood lams enough to crack the glass. Was he in a very humid area or bow in basement by chance?

Also I think the cracks at bolt holes on TDs can be caused by the same and blamed often on overtightening.

Another question, is any finish actually completely waterproof ?

[Mike Mecredy]

that's logical, he lives in Washington state.  It's not a take down.  

-Mike

[bamboo]

I've seen them develop on a dry fire

2nd what Kenny said...  My buddy bought a bow that has cracks in the fade area...  I believe it is due to moisture And wood swelling...

[mikkekeswick]

Yes wood movement. It doesn't take much force to crack glass.

[SportHunter]

Bear bows had a couple years with a lot of longitudinal cracks in their glass bows. I don't recollect the primary cause but it is present in many of the 1959-60s bows. May be climate related or due to using parallel glass at the time. The bows are generally still capable of shooting, I believe the horizontal cracks are more troublesome for structural integrity.