STEP 11: Making Rubber Molds and Casting the Parts
Continued ...
Erie Railroad Boxcars Part 3 - 1
48: The silicone rubber has been poured and is setting
up in the molds. This was one of those moments of
“I hope this all works and I can get the mold out of
the mold box.” Needless to say, it all worked, or this
article wouldn’t have been written.
I found a product called Smooth Cast 300, which is a
two-part casting plastic from an art supply store. This
is a white liquid plastic that you simply mix
The material I used to make the molds is a silicone
RTV manufactured by Tap. It is a two-part mix that
is a 9:1 ratio. You should be able to find this at
most plastic or art supply houses.
One of the keys in having a good mold is no air
bubbles, especially on a finished surface. Since I
do not have a vacuum system to remove any air, I
use the next-best thing. I turned on my jig saw and
let it vibrate for three to five minutes until I didn’t
see any more air bubbles rising to the surface.
I let a mold cure in the form for at least 24 hours
before I remove it. I then let the mold cure another
day or so before I try and use it. I don’t know that
all of the cure time is necessary, but it doesn't hurt
to have a little patience.
This was the first time that I had made rubber
molds. Those who have done it before know it’s
not difficult. To those who haven’t, don’t be afraid
to try it. It looks and sounds a lot more difficult
than it is.
MRH-Jun 2013
