Date: 7/8/2004 10:31 AM Central Daylight Time
Message-id:

On Thu, 08 Jul 2004 02:48:19 GMT, Richard Lamb
wrote:

For a mud plug I melt parafin (candle wax) in a double boiler (actually
a tin can in a pot of boiling water) and paint it onto the plug. It
will not be smooth - brush marks and drag lumps will look terrible.

Next, a hot air gun is used to melt the excess off with a careful rub
down while melted. This is to rub the wax into the surface - and burn
your fingers if you stay at the party too long!

Last, a couple of real good paste wax rubs.
Then a smooth coat of paste wax before starting the lay up.
Don't rub these paste wax coate _off_, tho.

Note that this is a fairly risky proceedure - both for the plug
and for the part. But it can work ok if you are careful and patient.

My experience - I built some wingtip plugs using foam board. Covered
them with drywall mud and after final sanding, sealed them with
urethane varnish. The recommendation was to wax them thoroughly with
paste wax and I bought a tup specific for the purpose from Wicks and
proceeded to wax the plug three times, REALLY putting it on carefully
and then buffing it.

I used fiberglass and epoxy resin and wrapped the plug (it was one
half the wingtip, the top part).

The resin bonded quite nicely to the plug and I ripped the plug to
shreds pulling the fiberglass off it. Ruined the fiberglass too.

The missing ingredient? Some kind of release agent on top of the wax.
I bought some PVA from Wicks and the next effort worked fine, after
rebuilding the plug.

Barring a release agent, which you mentioned you do not have, and the
type of plug, if you can wrap the plug with Saran wrap, or something
very similar, it will not adhere to the resin and you can pull it
right off the plug. But if the Saran wrap doesn't fit to the plug
well (perhaps you have trough's to fill that the saran wrap won't lay
into well, then using the urethane tape will work too.

One trick I heard of was to use an air gun to blast between the plug
and the layup to get it to pop off. I tried that and had some success
with the second layup, but ended up using a thin flat stick to wedge
in and push and prod to get things to release.

Corky Scott

I once needed to make some fiberglass hemispheres. I found a lightbulb the
right size, sprayed some WD-40 on it, layed up some fiberglass and it realeased
nicely. I then used the fiberglass form to make several hemispheres using
WD-40 as a release agent.

Dan, U.S. Air Force, retired