Another casting silicone from a silicone mould question thread...

[Odin82]

I've browsed the silicone casting from silicone mold threads in the past. So I thought all would be cool.

A couple of months ago, I was casting dragon skin silicone from a plaster cast, and the mold broke. Nothing big that can't be repaired. However, I thought it would be best to hold on to the last cast, and re-mold it, but this time with silicone.

Yesterday, I made a negative mold from the dragon skin silicone cast, giving it two coats of ease release 200. I then poured smooth-on Mold Max 30. This morning, I went to de-mold, and the two have sort of bonded… I managed to remove a corner with some force before heading off to work. I estimate it might take me an hour to separate the two later.

I had intended on casting some dragon skin silicone from the Mold Max 30 mold tonight, but am now fearful of a similar occurrence. Anyone have any tips, or have dealt with a similar problem?

 

[cavx]

I have different products but generally the sticking is not the same as full on valcanizing that silicon normally does without release.
Just be patient.

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[Odin82]

Thanks for the reply. It's my first time casting silicone from silicone, so I didn't know that this huge level of sticking was normal. I might give it a go this evening but may apply a lot more ease release, and see how I get on.

 

[mvaefx]

Unless you are using something in the lines of Smooth On's Inhibit-X within your Mold Max mould, and even then you run the risk of inhibition.Platinum silicone (Dragon Skin) into a tin silicone (Mold Max) mould is a big no no! Inhibition for sure! The other way around tin into a platinum mould is ok.

 

[Odin82]

Yep, I dun goofed and became aware of my error earlier while googling. Getting the price on the Inhibit X in the morning. I was aware before that tin - tin, platinum - platinum, but it completely slipped my mind!. I'd say the best bet is to use my original plaster mould, and repair the crack lines for the time being. Until I can get my hands on Inhibit X.

Cheers for the info guys!

 

[cavx]

Unless you are using something in the lines of Smooth On's Inhibit-X within your Mold Max mould, and even then you run the risk of inhibition.Platinum silicone (Dragon Skin) into a tin silicone (Mold Max) mould is a big no no! Inhibition for sure! The other way around tin into a platinum mould is ok.

Yes,wow! Great points. Mixing Tin with Platinum is as high risk as mixing air cured with additive cured. You might just end up with a big gooey mess.

Molding from a silicone mold should be no different to making any 2 part mold, except there won't be a cavity (from the master) inside.

When I did mine, the master was letters machined into hard plastic (Perspex). I made a mold of that part in silicone first which gave me raised letters on a flexible rubber sheet. I coated that with release and then made a second mold from that first mold. Now I had flexible version of the original machined part. This made extraction of the cast parts much easier than trying to dig them out of the Perspex. I was using flexible polyurethane BTW, so it was possible to get the letters out of the Perspex, but there was a higher risk of tears.