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Silicone Substitute


#1

Is there a suitable substitute for silicone spray mold release? I
live on an island in Alaska and so no ground shipping. Hazardous
shipping fees jack the price of a can up by $30!


#2

I use silicone" tire shine " from an auto parts store. Spray cans
seem to have disappeared, but it is available in bottles… It is
not a hazardous commodity this way.

jesse


#3

Have you considered making new molds ? If you want vulcanized molds
which don’t require any mold release and also give you a better
finish on your wax patterns, try either the Castaldo silicon rubbers
(Now they have several different colors) most likely denoting a
different durometer the lower the durometer the softer the mold, low
durometer is good for undercut pieces and very fragile patterns, high
durometers are better for large heavy patterns, Rio Grande also
carries Belicone silicon mold rubber I use both and they are very
good and both last a long time, I have some that have had over a
thousand pieces injected and they still have good detail, and it
doesn’t matter what you vulcanize like copper, brass, nickel silver
or pewter that will stand 330 or so degrees you get a good mold if
it’s polished before you mold it, you don’t get the surface
distortion and the mold cavity is as polished as what you put in.

If you don’t want to vulcanize Both Castaldo and Belicone make a
cold process rubber, it’s sort of like RTV but you can use
conventional mold frames and the material is more like a putty, I’ve
used both of them as well with good results,

Then there is also the traditional RTV silicone which is OK for
doing molds directly from wax patterns, there is ZERO shrinkage and I
suppose if you used a polished master you again would get a very
smooth cavity, I’ve been using the RTV from Zero-D for molding
directly from CNC wax patterns, it has given me better results than I
expected but this is a pretty expensive way to go and it’s pretty
messy, it has to be vacuumed, My major complaint about any of the
liquid type silicone is the molds don’t seem to hold up as well as
vulcanized silicone, Zero-D also makes a vulcanize able silicone
rubber I haven’t tried it, but I have used their RTV and their
investment, I like their RTV better than the others I’ve tried, Bill
is a contributor here occasionally and their service is very good,
and so is the service from Rio Grande, I’m guessing you have Rio’s
info here is the web addy for Zero-D www.zerodproducts.com

usual disclaimer I’m not associated with either company I just
donate most of my money to them just a satisfied customer

Kenneth Ferrell

http://www.shadras.com
(with a link on the front page to the best Jewelry info site in the
universe)


#4

Kenneth,

Let me ask you a question about the zero-D product (or any silicone
for that matter). If making a mold of a wax pattern, can you do a two
part mold…that is, something like a powder separation? How would
you go about it?

Thanks.
Fr. Alexis


#5

Fr. Alexis, I don’t think you can do a powder separation mold with a
liquid RVT. Castaldo and Belicone both make an RTV putty that you
could do a two part powder separation mold with, My only concern
would be that both of these materials need to be closed under
pressure while they cure, I don’t remember how long it takes for the
Castaldo cold mold but if I remember correctly it’s about 30 minutes
or less for the Belicold by Belicone, The RTV from Zero-D is very
transparent, and out of close to 35 molds last month I only damaged
one master, I still got a good mold as the master broke while
cutting, and these are very delicate patterns. The difficulty I see
in making a powder separation mold from a wax pattern is that the
pressure of clamping the mold could damage the pattern, the problem
with trying to make a two part mold with a Liquid RTV is that they
expand roughly 4 to 5 times their volume on the first vacuum and then
expand again after being poured into the mold frame and vacuumed
again, albeit not as much, I might be mistaken on the possibility of
making a two part mold from the Liquid RTV compounds, so you may want
to contact Bill at Zero-D or their their technical service number is
(800) 382-3271 or contact a technical representative at Rio Grande or
Stuller, possibly Andy Krouingold (I hope I got close to
spelling your name right) could tell you if it can be done, Rio’s
Ditto clear compound and Zero-D’s RTV are both transparent, and do
cut very easy, I probably cut 8 to 19 molds before changing scalpel
blades and you can see exactly where your cutting, I would imagine
they could even be cut with an Exacto knife for that matter.


#6

Fr. Alexis, Making a 2 part mold using the Zero D Products Akron
Clear RTV is done by mixing and de-airing 1/2 of the total quantity
of RTV you will need, placing your original in it, and submersing it
1/2 way into the compound. Let stand for 24 hours, then use a
seperating agent (I like cold cream myself) and apply it to the cured
surfaces where the RTV will touch. A thin layer just to make sure
there is a barrier is all you need. Mix the other half of your RTV for
the mold, pour on top of the remainder of the model and to fill the
area in the frame. De-air this, and let stand for another 24 hours.
Then remove from the frame, and you should be able to pull it apart.
If you have any more questions, Call Bill Mull at Zero-D Products
1-800-382-3271 he’s helped on any questions I’ve had. Craig Miller