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Vulcanized vs RTV


Hi Steve: I know you use our Akron Silicone RTV–thanks. You can
accelerate a platinum cure silicone’s set time dramatically with the
application of heat.

You will give up a little in shrink, but you can cure a mold in 1/2
hour or less.

24 hour cuRe:    		Room temperature
60 minute cuRe:    	122F
30 minute cuRe:    	212F
20 minute cure    		302F

With the sixty minute cure, you can copy a wax–note the low temp.

Bill Mull

 I believe we both agree that making an RTV of the wax and
producing a metal model is the best way to go...for production. 

Hi, Daniel–I think you are quite right. I sure don’t know the
details of how some companies successfully skip the metal model
step. You make a compelling argument for metal models. Really, my
expertise lies in the development and manufacture of rubber,
investment, and injection wax products for the industry.

You mention shrink, a favorite topic of mine. Amount of shrink in
and of itself is not as important as consistency of shrink. If you
have set anticipated shrink guidelines for your process and the
products you use vary in shrink from batch to batch, your process is
out of control. This out of control condition is not your fault,
unless you fail to seek out products that are consistent in nature.
The only thing you can control where it relates to shrink is
temperature. In a small shop, these variations are insignificant. On
a large scale, shrink variations in rubber or wax from batch to
batch can create headaches that manufacturing jewelers often
attribute to everything but the culprit.

How do you prevent these headaches? Do you have a procedure for
checking and recording the shrink of each batch as it comes through
the door? Developing such a history over a period of six months to a
year will be eye opening. The procedures are simple and worthwhile.

Best wishes,
Bill Mull