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[SGII] Modular Starship Terrain AND CASTING (OT?)

From: "Scott Clinton" <grumbling_grognard@h...>
Date: Sun, 28 Oct 2001 23:43:00 -0600
Subject: [SGII] Modular Starship Terrain AND CASTING (OT?)

Howdy All,

I have been doing a bit of mold making and casting of 25mm modular
terrain I just wanted to relate my experiences to those who care.

Firstly, RTV Silicone is great!  I will never use latex for mold making 
again for this type of thing.  I used Polytek PlatSil 71-20 and it
like a charm I also tried Polytek PlatSil 70-25 and although it worked
it is 
not nearly as good as the other.  I just had to be careful of a few
(as warned by others) like not whipping air into the silicone when
I had to paint the details before pouring and you have to pour
The most important thing as I can see is to have the entire process
out so that you are able to start and finish "the pour" without any 
hesitation while still not having to rush.  I had no big problems on my 
first 3 molds and I have been able to eliminate almost all air bubbles
(a vibrating table is on my Christmas list <g>).

My evaluation of the dental cement I used in casting though, is less
(Pemaco Ortho-Stone).  It works well enough, but it is pretty thick
when mixed according to the box.  And when I have diluted it so that it
flow well into the molds, I fear it is no stronger than hydrocal or
even reinforced plaster of paris.  My biggest letdown is that I don't
I will be able to use this dental cement at all for the small, two part 
molds I have planned.  It is just too thick (they are about 1/8" x 6" x
  But, I can still use it on some of the open face molds I have made and

will make.  It does mix very, very well and it has other advantages.

I then tried some Alumilite (resin) I picked up from the local hobby
This stuff works much, much better.  But, I think if I shop around I can

find a resin that is an even better match for what I want to do. 
seems to exhibit too much shrinkage for what I am casting, and it has
such a 
short pot-life that it can be tough to pour it fast enough.  I am 
investigating a resin "RP40" by Thermocast.

I have uploaded images of the first few resin pieces I have done.  One
is a 
wall and a door (they are actually cast separately) and the second is a 
floor hatch.  I think I will end up casting all the floor hatches in
cement though as I still have about 24.5 lbs. of the stuff to use up. 

(if Hotmail mutilates these links you may have to cut-n-paste)

Lastly, if this is too off-topic somebody just say so and I will shut up

about it, but frankly I am having a blast with this casting stuff.  I
recommend it to anyone that enjoys modeling.

Scott Clinton
The Grumbling Grognard


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