If you are making a mold of a porous object (such as one made
from plaster or bare wood), you must seal the object (shellac
works well) and then apply a separator such as wax or silicone
before applying the Por-A-Mold rubber. If your object
is non-porous (such as metal, rubber or glass), you need only
to apply a wax or silicone separator to the object. Perhaps it
should be noted here that if you were to make a silicone rubber
mold, it would be unnecessary to apply either sealer or separator
to your object before making the mold; however, silicone rubbers
are usually substantially more costly than urethane rubber.
If you wish to apply a thixotropic Por-A-Mold over
the object to be molded, it is best to begin by brushing a thin
layer over the surface, working the brush back-and-forth to gently
"scrub" the material into the details; then continue
building-it-up over the surface to the desired thickness, using
a spatula. A brush would generally be too soft for the purpose
of building-up a good coating of thixotropicPor-A-Mold.
Por-A-Mold Thixotropic tends to gel relatively quickly
(about ten- fifteen minutes, depending upon the volume of the
batch you prepare.) The greater the mass of the curing material,
the faster the gel; and the less working-time you will have. This
is due to an exothermic heat build-up which accelerates the gelling.
Also, if the room temperature is above 70-degrees Fahrenheit,
you will have less working time, as the gelling time is sensitive
to the environmental temperature of the area where it is kept.
To maximize your working time with thixotropic Por-A-Mold
, either confine your mixes to small batches (half-a-cup
of material or less); or, immediately after mixing-up the material,
spread it out over a larger surface such as a tray or over the
surface of your object . This effectively distributes the mass
of the mixture in order to reduce heat-build-up and slow the cure
process.
**Note: Por-A-Mold is not safe for use on the skin.
An alternative method for making yourPor-A-Mold urethane
mold is to first apply 2 thin layers of the pourable material
onto the surface of the original; allow each layer to partially
set for about two hours; then build-up the thixotropic over this
initial layer. This method offers an advantage over making the
mold entirely with thixotropic material in that there is less
of a chance that air bubbles will be trapped against the surface
of the original when using the pourable material than there is
with the thixotropic. We especially recommend this approach when
your original has very fine details. Of course, you can choose
to use just the pourable for the entire mold; however, you would
have to either use a box-type mold to contain the rubber and prevent
it from flowing away, or a proper support shell surround. Methods
for making poured rubber molds (as well as thixotropic molds)
are explained in Pink House Studios' technical video-tape,
"The User's Guide to Reducit, Rubber Molds and
Innovative Plastic Support Structures."
It is also essential, regardless of which type or consistency
of Por-A-Mold you choose, to mix the material very
thoroughly. We would even suggest that after mixing-up your batch
of material, transfer it to another container and mix it again.
This will bring the material that was originally at the bottom
of the first mixing container to the surface in the second mixing
container, ensuring that none of the material remains un-combined.
If the urethane is not properly and thoroughly mixed, it will
only partially set, remaining gummy or sticky in some areas.
Molds should not be opened until at least eight hours after completion.
You must use a solvent such as acetone or denatured alcohol to
clean away uncuredPor-A-Mold from brushes, mixers
etc. You may spray a silicone release or brush pastewax onto your
mixer before using it withPor-A-Mold; once fully
cured, the material may then be peeled away from the tool.
Por-A-Mold Pourable Soft S 111 2-gallon kit ..........$150.
Por-A-Mold Pourable Medium S 333 2-gallon kit......$150.
Por-A-Mold Pourable Hard S 555 2-gallon kit............$150.
Por-A-Mold Thixotropic Soft S 111TA 2-gallon kit......$130.
Por-A-Mold Thixotroic Medium S 333TA 2-gallon kit....$130.
Por-A-Mold Thixotropic Hard S 555TA 2-gallon kit......$130
Synlube 531 16-oz. can of wax spray-release ..................$9.00
Synlube 1000 16-oz. can of silicone spray-release...........$9.00