Sequoia Aircraft Corporation F.8L Falco, Construction Manual

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F.8L Falco Construction Manual 8–8 Revision 4, March 1, 2002
The effects of epoxy are cumulative. When you first work with epoxy you will not be bothered,
and you will wonder what all the fuss is about—then one day you will become sensitized. When
that happens, you will have burns on your hands from the epoxy, and you are in trouble for the
rest of your life. The problem never goes away.
One Falco builder working with T-88 became sensitized. He continues to like epoxies and has
bought a $400.00 “space suit” that painters use—supplied with air from a compressor. Tony
Bingelis is sensitized, and unmentionable parts of his body itch when he works around epoxy! We
once heard from a man whose father built a “Vari-Eze”. In the process of building this fiberglass
airplane, the man became sensitized. Unwilling to give up his project and with no alternative
adhesives available, he continued to work with epoxies. In the end, all of the hair on his body fell
out and has never grown back. It is possible to work with epoxies for your entire life without
becoming sensitized, but this always depends on observing the required safety precautions.
You should be aware that there is a problem with combining Aerolite and epoxy glues. Aerolite
glue uses an acid as a hardener, and some acid is left over after the glue joint is made. The acid is
normally evaporated within a few days, but if an epoxy joint is made over a fresh Aerolite joint,
the left-over acid can neutralize the epoxy hardening process.
Now, let's review some of the most popular epoxy glues. FPL-16A was designed by the Forest
Products Laboratory for use with wood. While the glue has excellent characteristics, it has some
significant disadvantages. The vapor is very toxic, and a number of builders working in enclosed
spaces have had serious health problems (involving the central and peripheral nervous systems).
The mixture is quite critical and requires careful measurement of the two parts—difficult when
small quantities are involved. The glue does not gap fill as well as some other epoxies. The glue
dries white and then yellows with age. FPL-16A glue may be purchased from Aircraft Spruce,
Wicks, and other suppliers.
Among homebuilders, the most popular epoxy is Chem-Tech T-88. It isn't hard to see why—the
glue is a one-to-one mixture ratio and comes in plastic squeeze bottles. For small batches, you just
squeeze out equal-length beads of each part, mix and apply. The glue dries clear and stays clear.
Chem-Tech says that T-88 will cure down to 35°F, although hardening takes about a week.
T-88 can be thinned with lacquer thinner and used as a sealer in place of the more traditional
varnish, but the thinner evaporates and creates a porous film. Chem-Tech sells a low-viscosity
epoxy called L-26 for just this purpose. Chem-Tech T-88 may be purchased direct from the
manufacturer: Chem-Tech Inc., 4669 Lander Road, Chagrin Falls, Ohio, 44022. Telephone
(216) 248-0770.
Applied Plastics (APCO) has developed a structural adhesive that is similar to T-88. This glue is
sold by Aircraft Spruce, Wicks and others. No testing reports are available to assure us that it is
any different from T-88 in performance.
Builders thinking of using an epoxy should consider the West System sold by Gougeon Brothers
Inc. This company is largely responsible for the resurgence of interest in wooden boats. As such,
Gougeon Brothers is probably the world's leading authority on the moisture protection of wood.
We are very impressed with the professionalism of this company. They maintain a large testing
facility and have done pioneering work on fatigue testing of wood and fiberglass—wood wins by a
large margin.