I would suspect the EA 40 myself. Three of us bowyers over here , after years of trouble free building have had numerous bows delaminate. Each one the failed area is devoid of any signs of glue , totally dry. We all know our lay up hasn't changed any way, each lam is well buttered , I even went to the oint of laying an additional bead of epoxy right down the middle, reasoning it would get spread to edges under pressure as extra insurance. air pressures the same, hotbox temps same, lams only cleaned with alcohol. Pre heat lams before lat up etc etc. and still we get failures. I have sent quite a few emaqls to smooth on, and it would appear they don' want to know about it. I am at the stage of seriously considering changing to another epoxy available here, only that its pot life is shorter during layups.Why this is all happening after years of success is a point of conjecture! Especially when there are three of us, and its destroying our heads and our reputations.NOT happy!