Quick-cure Epoxy

wrote in message
...
On Dec 22, 6:32 pm, Orval Fairbairn
wrote:

It will disassociate in time into a jelly-like goo, with no strength.
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Dear Orval,

You're right, of course. Any epoxy, fast or slow... CAN react exactly
as you've described. But the reason can usually be tracked back to
some problem with either the chemistry of the components or a problem
with the ratios. For example, more than thirty years ago I recall
using lots of "5 Minute" epoxy on at least three of the Varieze's
fabricated here in San Diego county. Fortunately, we never had any of
the 'epoxy problems' such as the one you described but a lot of other
builders did. Those problems were among the reasons that lead to
ratio-pumps, which have become pretty much a standard tool for
builders of composite aircraft.

However, for my own work, here at the shop -- especially when I need a
third hand and don't have one, I've found fast-curing epoxies to be a
very handy tool.

As for using such an adhesive in a structural capacity, I've got a
hunch the parts being joined would never be of any significant size,
since the 'cure-time' usually starts when the two parts are added
together. Then they must be mixed to a perfectly uniform blend, after
which comes applying the adhesive to the parts, etc. The point here
is that most of the year it probably takes me a couple of minutes to
get just a SMALL amount of them properly mixed... and I'm even worse
with filled epoxies, such as 3M or JB Weld. So if the stuff was for
something structural, it couldn't be of any size.

But I wonder if the Varieze owners have a Newsgroup or mailing list.
(They probably do.) And if they've ever run into this problem.

-R.S.Hoover

The "canard builders" generally, as well as the "Cozy builders" specifically
do have several support groups and mailing lists. The easiest way to find
most of them, and probably to select the best for a particular need, is
through a local chapter or directly through the EAA; and several of the
forums and mailing list groups also appear on a Google search.

I admit to being a ong time advocate of the "chapter" method.

Peter

Dear Orval,

You're right, of course. Any epoxy, fast or slow... CAN react exactly
as you've described. But the reason can usually be tracked back to
some problem with either the chemistry of the components or a problem
with the ratios. For example, more than thirty years ago I recall
using lots of "5 Minute" epoxy on at least three of the Varieze's
fabricated here in San Diego county.

Also, I have found (from model airplane building) that the chemical
resistance properties can be different from the quick to the long setting
epoxies.

The quick set is not nitro methane resistant, but the long setting resists
just fine.
--
Jim in NC