Interesting find, Paul. This appears to be a new hybrid product for Dow, based on a new liquid epoxy, DER 329 which is bis-A reacted with epichlorhydrin just like all the common boatbuilding epoxies. The product is shipped already promoted with cobalt naphthanate and dimethyl aniline, which reduces shelf life but increases safety. Some of these 3- and 4-component polymers are potentially explosive when mixed in the wrong order! The tensile strength of 12,100 psi is certainly up to boatbuilding requirements, and the heat deflection temp of 210-220 would seem to reduce the chances of weave printthrough or adhesive failure of hatch lid hooks in the hot summer sun.

Nothing in the Dow literature refers to adhesion to wood, which is weak in the standard vinyl esters. Perhaps the epoxy modifier improves this characteristic, but some testing would be in order. Also, cobalt-promoted liquid resins tend to have a purplish cast when cured. This product is touted as resistant to acids, alkalies, bleaches and solvents, for use in industrial containers and processing areas. Aesthetics would not even be on the list of design criteria.

Sidebar: I used a non-Dow, non-hybrid but high quality vinyl ester resin broadcast with silicon carbide aggregate on my Doug fir wood front steps in '97. This was installed in August during a dry spell, after having been pressure washed, dried and sanded. By February the edges were starting to curl, and by spring it came off in sheets. This is partially explained by the dimensional changes in the wood with changing humidity, but the same forces are at work with a boat. I had been thinking about using the vinyl ester in a kayak project, but went back to epoxy after this admittedly unscientific test.

: Aircraft Spruce has this for $30.95 a gallon. at that price it becomes a more
: practical alternative.

: www.aircraftspruce.com

: And they have this blurb about the product: VINYL ESTER RESIN
: MEDIUM PROMOTED: Includes CONAP, DMA and other additives. Add MEKP for
: complete cure: P/N 01-07350 $30.95

: Dow Chemical's Derakane 411-350 PA Vinyl Ester Resin is an epoxy-based Vinyl
: ester designed to provide superior toughness and high corrosion
: resistance. Many leading kit aircraft manufacturers use vinyl ester resins
: extensively due to its quality and ease of fabrication. We furnish medium
: "promoted" vinyl ester 411-350 PA resin which includes CONAP,
: DMA the resin is cured by adding the MEKP which is furnished with the kit.
: Gel times vary according to the amount of MEKP added and the ambient
: temperature. Shelf life of promoted vinyl ester resin is short at only a
: few months.

: - - - - - - - - -

: I'm intrigued by the concept that this is an "epoxy-based"
: material. Maybe someone can explain that particular chemistry to me.

: PGJ