Sheeting Foam Wings with ProBond Polyurethane
Jim Ryan
For years I’ve used 3M Super 77 to bond the wing skins on my foam wings. But at long last, I’ve found what I believe is a better way.
ProBond polyurethane
is an
adhesive that foams slightly and cures in the presence of moisture.
This makes
it great for sheeting foam wings, since it makes a strong bond and also
fills
any gaps that might exist between the core and the skins.
The glue looks like honey, and it's applied to the prepped and cleaned
wing
skins much like laminating epoxy; dribble on a little and spread it
with a
squeegee. You want the surface of the wing skin to have a uniform sheen
of glue
on it.
Once the glue is applied to the wing skins, the wing core is wiped with
a wet
sponge to make it slightly damp. The water is the catalyst that
will cause the
glue to foam and cure, so don’t forget this step.
Next the whole works
is laid up in
the wing beds - bed/skin/core/skin/bed - and stacked up with
weights. Be
careful of the alignment, as this will determine how straight the wing
will
be. It’s almost impossible to use too much weight.
Allow the stack to dry at least 24 hours. The moisture on the
cores will cause
the glue to foam just slightly and then cure. I've been impressed with
how
aggressively the skins adhere to the cores. Once the panels cure,
you can
proceed with assembly.
This method is
well-suited to
vacuum bagging, but it also works fine if you don't have the equipment
to bag
wings. Good luck!
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