Interesting article. He seems very credible — nonetheless, he still represents a commercial epoxy brand. The article still raises questions about penetrating epoxies though. They just caught my attention recently — so I thought I would experiment. Looked like standard West epoxy penetrated through the entire balsa block though.
However, as both Swied and Jrandy commented, they seal balsa to prevent dry laminations. Dry laminations indicate the balsa is absorbing a significant amount of the epoxy resin used to laminate. Even a thin layer of wood fiber penetration has the same effect as it does in FG or carbon cloth. Fiberglass skin thickness is fairly thin at approx. 0.3 mm for 6-oz FG.
I have sealed Baltic birch plywood and pine with epoxy with SB epoxy (not used for Surfcraft). I do it because the wood absorbs epoxy resin. I seal so I can get a smooth, glassy epoxy surface with a second coat (no FG added). Hemp and linen cloth used for SB laminations are composed of the same type of fibers in wood.
So, I see pre-sealing balsa with the same epoxy resin used to laminate the FG added as a benefit/advantage. Reduces amount of epoxy needed to laminate. Also, if epoxy sealed balsa is laminated while the seal coat is green/uncured, the bond should be chemical rather than mechanical.
BTW Gene recommended pre-sealing blanks with resin before glassing.
“6. Sealing- Sealing the blank makes for a better bond to the foam by reducing the chance of a plural space developing between the foam and glass as the resin soaks into the foam during the drying process, especially when tight weave (ie: 4oz or flat weave) is used next to the foam. With proper application sealing shouldn’t add weight and net resin use should remain the same since sealed blanks require less resin to lam. Note that squeegee technique and faster cure times are are always big factors to achieve a good bond, especially if the blank isn’t sealed.”
https://forum.swaylocks.com/t/glassing-weight-vs-strength/33216/10
Just sayin’