|
A:
How
you apply any brush-on rubber will mean the difference
between success and failure when making a brush-on mold.
The
key to being successful is to understand that you will be
applying the rubber in
very
thin layers,
especially the first layer. If you mix and apply too much
rubber on to the model’s surface, it will sag or run off of
your model. Over applying is a waste of valuable rubber.
Entrapped Air –
Brush-On rubbers need to de-air themselves, just like
pourable rubbers. Over applying rubber onto the model’s
surface will result in air entrapment which will result in
air bubbles being evident in the cured mold and any castings
made from that mold.
It’s
All In How You Apply the Rubber, Especially The Critical
First Layer . . .
Read
the technical bulletin for the brush-on rubber you are using
before you begin.
To
begin, mix a small amount of rubber. If you mix more than
you can apply in 15 minutes, what remains in your mixing
container will set up and become unusable. You can always
mix and apply more during the mold making process if you run
short. Add a small amount of SO Strong color tint to every
other layer to help you find your way and ensure thorough
coverage.
For
The Critical First Layer . . .
Using
a stiff paint brush, apply a thin layer of rubber over the
model’s surface. Use gravity to your advantage by starting
at the top of the model and working your way down to the
bottom. Using a “stippling” motion will work the rubber
into deep detail.
When
you are finished, you should almost be able to see through
the rubber to the model’s surface. Don’t worry, Smooth-On
brush-on rubbers melt into themselves nicely and your model
will be covered. The thin first layer of rubber will de-air
itself, resulting in a virtually bubble-free mold.
Layers
2, 3 & 4 . . . can be applied using more material, but not
too much.
For
more information about making a brush-on mold, you can read
Smooth-On’s “How To Make Molds & Castngs” manual or view
Smooth-On’s “Making A Brush-On Mold” DVD.
|
Smooth-On