AlexM Posted August 2, 2015 Share Posted August 2, 2015 Hello there, I'm currently making my first experiences with silicone moulding and resin casting. Yesterday I made my first silicon mould - and totally messed it up, as the object I wanted to mold detachted from the ground and than was then swimming within the silicone while curing . Seems to be a really learning-by-doing-process... No I have an unusable lump of hardened silicone which is annoying considering the high price of silicone I wonder if I could cut the failed mould into small pieces and reuse them when making a new (hopefully successful) mould by mixing the small hardened pieces with fresh (two-component) liquid silicone. Will the liquid silicon "merge" with the small parts, so that I get a homogeneous mass at the end? Cheers Alex sandokan 1 Link to comment Share on other sites More sharing options...
BiggTim Posted August 2, 2015 Share Posted August 2, 2015 I've had that happen, too. I'd say yes, the pieces should bond well with the new stuff, but I can't guarantee that they will align as well you're hoping so the best I can say is to give it a shot. What do you have to lose, right? If works, then you saved a bit of mold rubber. If it doesn't, then you wasted some. All of who've tried resin casting have wasted a bunch learning the process. Tim AlexM 1 Link to comment Share on other sites More sharing options...
D Bellis Posted August 2, 2015 Share Posted August 2, 2015 (edited) I wonder if I could cut the failed mould into small pieces and reuse them when making a new (hopefully successful) mould by mixing the small hardened pieces with fresh (two-component) liquid silicone. Will the liquid silicon "merge" with the small parts, so that I get a homogeneous mass at the end? Yes, I do this frequently. Make sure to wash any release agent off of the mold being scrapped before using chunks of it as 'filler', and they will become one with the new molds. HTH, D Edited August 2, 2015 by D Bellis AlexM, sandokan and Out2gtcha 3 Link to comment Share on other sites More sharing options...
AlexM Posted August 2, 2015 Author Share Posted August 2, 2015 Thank you guys! Then all is not lost Link to comment Share on other sites More sharing options...
phasephantomphixer Posted August 3, 2015 Share Posted August 3, 2015 Also, try to keep the recycled hunks away from the item as it can leave surface marks when you cast. D Bellis and AlexM 2 Link to comment Share on other sites More sharing options...
AlexM Posted August 6, 2015 Author Share Posted August 6, 2015 Also, try to keep the recycled hunks away from the item as it can leave surface marks when you cast. Thanks for the advice! Link to comment Share on other sites More sharing options...
stevegallacci Posted January 22, 2016 Share Posted January 22, 2016 Been bulking up molds with chopped old material for years. Yes to keeping the old stuff away from the pattern area also as the new mold material may differentually adjust as it cures. Not nessisarily shrink, but may do some kind of dimensional dance, and there may be some distortion. And along with that is the matter of sizing your chunks. Smaller is better. However, for some mold shapes, you can, in effect, re-line a fresh impression into a bulky mold. Another thing with old material mixed with new stuff, the new material may cure slower if you have a lot mixed in. HOWEVER, the clear-ish platinum silicon mold material will not adhere to itself, so doing a mold in more than one pour with some setting time between them won't work, nor can you recycle old material into a new mold. Link to comment Share on other sites More sharing options...
wunwinglow Posted March 30, 2016 Share Posted March 30, 2016 Also, if you do try to reuse old moulds, try not to include any material from the cavity. because the isocyanates absorbed into the rubber will inhibit the cure of the fresh rubber. We don't bother trying to reuse old moulds, the time it takes to hack up old moulds is much more valuable making new moulds from fresh material. Also, buying rubber in large quantities brings the price down even further. Link to comment Share on other sites More sharing options...
AlexM Posted April 1, 2016 Author Share Posted April 1, 2016 I experienced that cutting silicone into small pieces with the knife is very tiring. Is there a way to chop/grind it up? Link to comment Share on other sites More sharing options...
D Bellis Posted April 1, 2016 Share Posted April 1, 2016 I experienced that cutting silicone into small pieces with the knife is very tiring. Is there a way to chop/grind it up? Much to my wife's dismay, I commandeered one of these from her kitchen for that task last time, and it made the job easy: http://www.amazon.com/Ulu-Company-Knife-Wood-Handle/dp/B004CUO4MO/ref=sr_1_6 HTH, D Link to comment Share on other sites More sharing options...
AlexM Posted July 13, 2017 Author Share Posted July 13, 2017 Hi there, I recently saw this video on youtube: https://www.youtube.com/watch?v=aZ_k895KzdI I gave it a try and ordered the cheapest hand driven meat grinder on Ebay for just 10 € with free shipping. The frist attemp was quite promising. This is the result of an evening of work. The size of the grinded silicone varies, from rather large to very small pieces. I think that repeating the process would result into even finer grinded parts. I have no weighing scale at hand, but I guess the value of the grinded silicone is at least 10 € Link to comment Share on other sites More sharing options...
Mustang JBB Posted July 13, 2017 Share Posted July 13, 2017 I experienced that cutting silicone into small pieces with the knife is very tiring. Is there a way to chop/grind it up? If your old molds are small, maybe a coarse cheese grater. Link to comment Share on other sites More sharing options...
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