"Yes I added a small amount of 407 with the epoxy during the lay-up of the first layer it helps stiffen the lay-up and fill any small holes in the foam. My NA recommended it. I made a few test panels and the panel with 407 mixed in was much stiffer then straight resin. Epoxy resin is slightly elastic and the bog helps make it stiffer. The amount of 407 is slight is not like I’m making a filler paste to a peanut butter thickness. The lay-up was vacuum bagged with two layers of the 200-gram carbon unidirectional cloth. Why do you seem so against it Robert?"

I am aware of the flexibility of the epoxy resin...you can get different resins with different modulus of elasticity. Resin Research Inc. blends one specifically tailored to Carbon, Kevlar and S-Glass. My concern is strength of the laminate, not stiffness. The school of thought I am coming from is that the distance between the skins (thickness of the core) provides the stiffness. But, hey...everything is subject to change without notice right...LOL and if your test panels can increase stiffness while maintaining all the strength of a laminate without 407 all the better....

Regards,
Robert