My old blonde double bass has cracks & seams which were repaired with fiberglass a long time ago (outside repairs). There's a 1947 repair label inside the body which quite possibly is the date the work was done. Looks old. But despite the unorthodox methodology it looks fine - the fiberglass was sanded & smoothed, & cracks cleated from inside, and all is holding well. I was going to remove the stuff but having second thoughts... I wondering if anyone else has encountered this and would like to share their thoughts. I read that fiberglass was invented in 1938. Its quite possible its been holding my bass together for 75 years.