I’ve bellied a couple bows with the red fiberglass pictured here. The bow above was the first I tried backing with the stuff — elaborated on here. Maybe I’m wrong, but as far as I’m concerned, electrical grade fiberglass is not bow-backing material. I’m next to certain it was the weak link in this bow’s design chain. On the other hand….
If I wanted to add 15 or 20 pounds to an otherwise working bow, I’d slap this crap on the bow’s belly and get ready to tear a shoulder muscle.
I’m only guessing — from a starting point of almost pristine ignorance — but I don’t think this particular type of fiberglass has any appreciable under-tension strength. And a bow back needs to be able to handle tension. On the other hand…
The stuff seems to be a monster when it comes to handling compression — which is the type of stress the bow’s belly undergoes. And this strength is only available if the limbs are otherwise in good working order. Here’s an example of a bow that experienced a bad chrysalling and collapse, and what happened when I added this fiberglass specimen to it.
Oh how I hope this bit of information saves someone as cerebrally challenged as myself the expense and hassle associated with buying and using this, I’m sure wonderful, product that all but the most
feeble-minded adventurous bowyers must avoid like a drunk Jehovah’s Witness.