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Answering the Epoxy Question
From DP84, Page 4 (April, 1996)
It seems several laminating
materials have gone the way of the buffalo, disappearing from market shelves only
to reappear briefly in small quantities before dying out for good.
It has put some homebuilders in a tailspin, stranding them with partly built aircraft and a possible compatibility problem. While the good news is that new products are on the horizon, the bad news is that homebuilders will have to decide what tradeoffs they are willing to accept.
RAF reported in CP 77 that its sister company Scaled Composites (SCI) would no longer use Safe-t-Poxy as it was found to contain MDA (a known carcinogen) and styrenes (highly allergenic). "We buy resin in 55 gallon drums, sometimes 10 drums at a time," explained Mike Melville, "and we have 100 employees now. We dont want to subject our employees to even the threat of MDA contamination." The same goes for homebuilders", he continued. "They have to know, even if it's the smallest of a million, that Safe-t-Poxy contains a known carcinogen."
In addition, Hexcel sold its Resins Group business, which included Safe-t-Poxy, to another company. The new owners decided not to continue the resin line, and Safe-t-Poxy suddenly became a thing of the past.
Unfortunately alternate epoxies recommended by RAF in CP 77 have since been discontinued. SCI scrambled to find a MDA-free replacement and now uses a laminating system called Pro-Set distributed by Gougeon Brothers Inc. located in Bay City, MI.
To add to the confusion, a "near-exact replacement' for Safe-t-Poxy is now on the market according to a recent letter from Gordon Bowen, former Product Manager at Hexcel. "We've now introduced via Aircraft Spruce of LA, GA and Diversified Materials of San Diego the near exact replacements for 'Safe-t-Poxy' systems, 'E-Z Poxy'," writes Bowen. "The chemistry and technology remains as close as possible without violation of any rights retained by Hexcel. The mix ratio is the same, the long pot life and storage stability remain the same, the excellent fabric wetting and adhesion remain the same. The most important aspect of Safe-t-Poxy technology is the fact that this chemistry is the only chemistry to have a 20 year track record/pedigree, in existing homebuilt's critical structural parts and gas tanks, without known failure."
According to Bowen the resin and hardener can be ordered in small packages from Spruce and DMC. The slow hardener is EZ-87 and the fast is EZ-83, the resin is EZ-10. It is compatible with Safe-t-Poxy materials the homebuilder may still have on hand from previous purchases of Epolite (these epoxy systems were known at Hexcel as Epolite 2193, 2184 and 2187 hardeners and Epolite 2410 resin), depending on how 'old' the previous material may be but needs to be checked by the builder. The chemistry is compatible, he says.
"Because I've been involved with the EAA since 1974, coordinated the Composites Workshop at Oshkosh several years, given tent forums on composites and resins, built a lot of my Cozy IV using Safe-t-Poxy and had been the Product Manager at Hexcel for these systems for 7 years, I decided not to let the Safe-t-Poxy type technology die at the hands of corporate lawyers and non-homebuilder business managers," Bowen explained in his April 96 letter.
RAF can't comment on whether or not you should use E-Z Poxy, which more than likely contains MDA. It's up to you to ascertain how much MDA is contained in E-Z Poxy, if any, and what the risks are. We suggest you discuss the subject with Gordon Bowen at (801) 394-5537.
If you decide to use E-Z Poxy, we would recommend that you use EZ-10 and EZ-84. But remember, it is up to you! Check it out!
Since RAF no longer has the resources to conduct testing on "new" or different products like this, we would appreciate feedback from those of you who do use it.