Re: Polyester Casting Question(last one promise!!)


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Posted by bruce paul fink on March 21, 19100 at 07:16:18:

In Reply to: Re: Polyester Casting Question(last one promise!!) posted by Eric on March 20, 19100 at 12:58:43:

Don't make it the 'last post' question or response. I love to see the many ways others

offer up their thoughts, questions and solution answers as it teaches me some gaps and

lapses of my own.

These are good ones which relate to many other dimension conquering areas.

Give me a few more days and I'll do some specific responding on this as I use major

amounts of this stuff (like about three 55 gallon drums a year) in many forms and in

many ways and have been doing so since 1957 when it was first coming out.

Polyester resins have improved so much since then and some of the rules then are no

longer needed while new ones have come into play.

Meanwhile this media is just an off to the side media for me and I work with it more

often than not as a filled media so the color and opacity is integrated throughout.

As for the wood mold question... has to be sealed with a good wax or waxed finish

over it so no porosity remains. Many sealers work and commercial product info on

this can be gotten from (amongst others)

I however use my own mix the most which is made in quantity from a good hard wax

grade (Victory or others... addresses follow in the wax post coming up) that is melted

and when nearly cool liquid again is poured INTO about 6 times the quantity of cheap

paint thinner. Stir as it goes in and let set for a few hours or more. Proportions need

not be exact as this makes a wax that is now in liquid form and will brush and flow on

into pores, etc. and then by simply letting set overnight or longer to evaporate

becomes a very thin film of hard wax again.

The commercial products work just as good but I make this by the gallon and use it

just as fast. Saves much bucks. This will also seal dry plaster, and many other form

mold media.

As for the thoughts on do you wait for the tackiness to subside before pouring the next


The tackiness you may be referring to is intended as a natural surface that will resist

hardening so the next layer has a better chance of adhering. Don't wait.

I have been led to understand that some products have a very minute quantity of wax

in the plastic that is intended to float to the surface (referring to laminating polyesters

here) and it is this hint of a wax layer that seals the surface so it is NOT tacky and

does cure. If you want a good, better , best bonding you wipe the wax off with a

lacquer or acetone rag (gloved hands of course) and expose the surface plastic again

before adding more. If you want a final hard surface cure and that wax in not in the

formula. simply seal the finish as it gels with a fine spray of clear lacquer or such....

SO do not wait, and in fact it sticks and becomes adhered even better if you have it

tacky. (Splitting hairs here though, as these are the types of rules one does if into

major items like boats of things that go bump in the wavy nite.)

And back to the wood mold thought...

Why wood unless it is easiest to do as a mold. It suggests to me that this might be a

geometric form and wood working tools assist so OKAY but if this is any restriction

lets jump to any other types to achieve your goals.

Check out this posting on wax working since that is a natural polyester resist mold

media and see what you think there.

It's an old post but still quite valid.

And for the show and tell combination thingy... here is a polyester resin filled (with

marble sand and green type earth dyes) Still Life Form that was done by using an

original that was made from wood for the main frame and the custom picture frame as


from 6 inch dia.. PVC pipe,

from styrofoam and urethane foam plastic sheets cut on a table saw and both shaped

and routed,

from a heavy wax soaked cloth which when hardened and in final form place was also

covered with some fine wedding lace on it's surface,

and and with about an additional 30 to 40 lb. of victory wax to blend it all together.

Then a mold taken off that (in this case a polyurethane rubber one) and backed up

with a polyester resin fiberglass and wood framed mother mold.

And the rubber mold surface was sealed with the above mentioned water like wax

seal (sprayed on with an atomizer, this thing is about 6 ft tall).

And finally the whole was cast in a polyester resin and marble mix along with interior

wiring (for an integrated 12 volt light on the back side), a top side stainless steel bolt

anchor system for easy lifting later and a lower hollow anchoring and installation

system so this about 600 lb. monster could be handled and set up safely and either

permanently or temporarily as needed.

It is at

The smaller parts on the pedestal and some of the other details are cast bronze.

Got to go to work.



PS. the bear seen behind it while I was cleaning it is not part of it.

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