OT- chopping up & recycling silicone mold?

[challenger]

I've seen people use a meat grinder for this but I don't have one. Cutting up silicone is a PIA using a blade. Anyone have a better idea to chop it up fairly small?

[Dan Dubeau]

slap chop. (would probably work though....)

I just use scissors. Depending on your new mold shape It doesn't have to be in tiny pieces. I like using bigger chucks in the corners so that only fresh liquid silicone is touching the model. With the granulated meat grinder method you don't really have control over that. TBH I don't know whether it even matters or not though.

[challenger]

Thanks. I think I've settled on a food chopper.

[gellfex]

Not that I think it's the best method, but those hand cranked meat grinders can often be had at a Goodwill or Salvation Army. Problem is it needs to be cut up like you already have there to fit in the grinder!

[darryl]

Presumably to use as filler in new molds?

[dian]

not sure what you are doing, but you know cured silicon will not bond to fresh resin, right?

[challenger]

not sure what you are doing, but you know cured silicon will not bond to fresh resin, right?

I'm using it as a filler.
Did you mean to say cured silicone won't bond to liquid silicone? If I'm using it in a mold I wouldn't want it to adhere anyway so?

[JoeLee]

Presumably to use as filler in new molds?

I have to question that too. How do you really recycle it?? maybe repurpose is a better word? You can't melt it down and use it over again. Unless there is an industrial method of doing so. Like paper, steel plastic etc.

JL..................

[Dan Dubeau]

Cured silicone will bond to new silicone, as long as it's clean and oil/release free. It's pretty common practice to recycle old molds by chopping/chunking them up and using them as filler in new molds. Silicone is expensive, and using old stuff can really lower you cost per part.

[Noitoen]

I have to question that too. How do you really recycle it?? maybe repurpose is a better word? You can't melt it down and use it over again. Unless there is an industrial method of doing so. Like paper, steel plastic etc.

JL..................

Not with silicone. Mixing chunks of recycled silicone helps reduce the volume of new silicone in bigger mold making. Silicone isn't cheap and if you can recycle some in this way it's better.

[challenger]

^^^^^.
Yes silicone IS expensive. To the tune of about $40.00 just for this one mold.
People who do silicone mold casting recycle it all the time and it IS recycling not repurposing.

[dian]

Cured silicone will bond to new silicone, as long as it's clean and oil/release free. It's pretty common practice to recycle old molds by chopping/chunking them up and using them as filler in new molds. Silicone is expensive, and using old stuff can really lower you cost per part.

have you tried it? poured some resin on a cured object and tried to separate them?

[Dan Dubeau]

have you tried it? poured some resin on a cured object and tried to separate them?

Not sure I 100% understand your question (use of the word resin? vs silicone). Yes, I have recycled old silicone molds by chopping them up and using the silicone chunks as filler in new silicone molds. I have then cast fresh resin in those molds with zero issues.

[dian]

sure, the chunks are enclosed in fresh silicone resin and the casting keeps its form. but how strongly does the new silicone adhere to the chunks? you could maybe have used chunks of anything flexible to get same results.

[Dan Dubeau]

Near as I can tell it's a full chemical bond. I've even had success using cured household silicone caulk as filler. It's a bit stiffer than molding silicone, so it plays with the durometer of your mold, but it was a successful experiment (surprisingly). I'm designing some stuff to be cast right now, and when I go to make the molds I will most likely use caulk strips for filler around the outside to see if I can get a stiffer outer shell, with a more pliable inner. Mostly because at the moment I don't have any old molds to retire, and second, because I like experimenting. A tube of caulk is $5 vs about the same volume of molding silicone @$40 up here. I played around a lot with trying to use caulk for molding, but it turned out more trouble than it was worth.

I'm not sure you could use anything else as filler, but maybe? If it was fully encapsulated it might work, but it probably wouldn't bond to the silicone.

I've still got a couple more ideas to prove out to reduce my mold cost, but only so much time to play around .