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 Post subject: Mold question
PostPosted: Thu Nov 21, 2002 8:59 am 
If i'm looking at something to buy there are lotsw of statistics, and I know nothing of them. The ones i think are important are shore hardness, mixed viscosity, and tear strength. For a mold of fairly normal pieces (with undercuts and such)what are the ranges of these that i want to get?

I obviously know that idealy it is highly viscos, and doesn't tear at all, but what are the acceptable limits?

Thanks for any and all help,


 Post subject: silicone rubber
PostPosted: Fri Nov 22, 2002 8:59 am 
You've got some competing requirements for your rubber. Typically the silicones with the best tear strength (a must if you've got undercuts) are very thick before curing. This can make them hard to pour, and they require a vacuum chamber for degassing. Silicones that pour easily are usually more prone to tearing, and won't do well if the shape you're molding has undercuts. I'd recommend doing whatever you can to eliminate the undercuts so that you can use an easily poured silicone that doesn't require degassing. It'll be much easier to work with, and the parts will be just as good. There's a company called Smooth-On that makes some very nice silicones that are easy to work with.

 Post subject: Rubbers
PostPosted: Sat Nov 23, 2002 2:44 pm 
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Joined: Wed Nov 24, 1999 12:18 pm
Location: Palerang Shire, NSW, Australia
Check the rubbers article for some recommendations. Top fav is Dow Corning 3110 RTV.

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