fiberglass resin for auto bodies

[vth0kie12]

will fiberglass resin and fibberglass cloth you get at an auto parts store work for a backing on a longbow, or will it be to hard and brittle.

[bjansen]

I backed a short osage bow with fiberglass cloth and smooth on once and it cracked.  I then pealed/scraped it off. My best guess is that will happen with the resin and cloth as well.

[mater]

Polyester resin is to brittle. The glass cloth with epoxy resin should work. You can get epoxy resin at boat building or repairing stores or sites.

[monterey]

I backed a small kids bow with the automotive fiberglass but did not use the automotive resin.  The epoxy I used was some two part stuff that I got from the hobby store that is used a lot by model plane builders.  Got no brand name for you since it was packaged under the name of the hobby store.  

It's still going fine but is not a high stress situation.

I build three other identical bows at the same time each with different backings.  One was rawhide, one fiberglass, one paper bag and one 10 oz cotton duck.

They all seem to shoot the same.  There may even be a bit of advantage to the paper bag backed bow!  My theory is that being the lightest of the four it has less effect on the efficiency of the bow.  The glass I thought would be the winner in that respect given that it should actually contribute to the bows cast but apparently any added cast provided by the glass is offset by it's weight.  I could not do much of a comparison with the rawhide backed cause I gave it to a friends little boy before I could really test it.

[Maxximusgrind]

I used automotive glass on a 40 pound canarywood bow several years ago.just one coat of 2inch fiberglass tape and it is still working.But its pretty long and only 40 pounds.If I remember right,I wiped off as much resin as I could to keep it thin.I would think the marine stuff would be more flexible?