mold release

[kevinbatson]

what is the best release agent to use on a bondo fiberglass resin mold? My urethane foam is still sticking to the mold and will not come out....

[CrabCrazy]

johnsons or minwax paste wax

[Randy Miller]

A good carnauba wax buffed smooth on the bondo first, followed by a good coat of polyvinyl alcohol (PVA)

[CrabCrazy]

i foamed forms in plaster and resin-bondo...needed saw a need for PVA...unless it was a detaied cast...never had no problems with the foam sticking...as the foam heats and expands the wax stays on the outside skin..but thats just what worked for me...if its that detailed as with a turkey head or something,,then i would use PVA

[beaker]

Foam needs a wax release... the hard waxes stated above are good choices

[Clew]

I want to ask a dumb question
What do you mean by hard wax?

[CrabCrazy]

i think hard waxes would be minwax or johnsons paste wax, because they are solid, while liquid wax such as auto are liquid

[John Helm]

Vaseline works pretty good as well.  Just make sure it spread very thinly and rub it in well to prevent any undesired texture from showing.

[John C]

On bondo resin molds, I seal then with shellac, thinned with denatured alc. then once dry brush on a heavy coat of Johnsons paste wax
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polish it and give a second heavy coat and polish it. the part will almost pop out of the mold.

I just molded a large trout head with bondo resin and cast it with bondo resin, been doing it this way for 30 years.

[Kerby Ross]

I use bondo to make my cactus molds and use bondo/resin to pour in my molds and all I use is car wax for mold release and they come right out.



Kerby...