Fixing A Silicone Mold

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crokett

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I poured 2 molds the other day, one for euro/slim line pen blanks and another that was supposed to be for casting bottle stopper blanks but messed up. There are holes in the bottom of of the stopper mold, not large. I was also thinking of cutting the bottom off and turning a PVC plug from some PVC trim I have. I think the silicone would seal well enough around the plug to be able to use it for casting.
 
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Ive had silicone molds tear out after years of use and just used flexible silicone caulk in the crack and pushed them back together. Worked just fine for the fix so I don't know why you couldn't just smear some caulk in the holes and let it set up.
 
The RTV is a good suggestion. My experience with the silicone from the big box stores so far is it doesn't stand up to the heat from the crock put during casting. I have used it to seal wood molds and it peels off.
 
The best bet is Silicone. Preferably the same silicone you made the mold from. You said you made the molds, right? Do you have any extra that you can plug the molds with?

If not, 100% silicone caulk from a tube will do the trick. The only thing that will stick to silicone is silicone.....
 
I don't have any more of that silicone. At 35 bucks a pop, it is not likely I will get more any time soon. I couldn't find anybody who was selling a mold for euros, so I got the silicone to do it. Thinking about it I probably could have gotten it done custom cheaper or at least same price that I paid for the silicone I bought.
 
crokett said:
I don't have any more of that silicone. At 35 bucks a pop, it is not likely I will get more any time soon. I couldn't find anybody who was selling a mold for euros, so I got the silicone to do it. Thinking about it I probably could have gotten it done custom cheaper or at least same price that I paid for the silicone I bought.
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Euro is the same as the Designer. I have them if you still need them....
 
I'd say you should hit the dollar store and see what they have.
I've used caulking.. works just fine. I've used aquarium sealer. Works
just fine. I've used bathroom sealer. Again .. works just fine.
I think we all touch up our molds from time to time.. we snap out the
castings, snap in tubes.. blow compressed air into them to shoot out
blanks.. bake them, shake them and all around abuse them. But you
can always bring them back with a little more silicone.
 
PTownSubbie said:
Euro is the same as the Designer. I have them if you still need them....
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no, but I might be interested in a sierra/mesa mold if you have them. I know I can get them cheaper than I can make them. I think that is the same tube as some of the others like lancers.
 
crokett said:
no, but I might be interested in a sierra/mesa mold if you have them. I know I can get them cheaper than I can make them. I think that is the same tube as some of the others like lancers.
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Send me the tube sizes and I can tell you which mold will work. Definitely have the Sierra....
 
Sierra/Mesa is the same size - 27/64". I have made both those kits and used the same bushings for each. As per woodturningz.com. The Lancer is compatible with the Mesa.

oh, and back on topic, adding more silicone worked just fine. It never occurred to me that silicone would stick to itself. All those years of adding new caulk to windows, doors etc and first thing you hear is to get rid of the old so the new will stick.
 
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crokett said:
It never occurred to me that silicone would stick to itself. All those years of adding new caulk to windows, doors etc and first thing you hear is to get rid of the old so the new will stick.
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The reason for that is contaminants. Dust, air and sun will age caulking on surfaces and will cause a skin that will not usually be silicone to silicone contact anymore.

As for mold repair, I too use silicone caulk and it works like a dream. If anything, I think it holds up better as I can't remember having to repair a break that I patched with silicone ever again...
 
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