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Pouring Part B silicone in two sittings?!

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Pouring Part B silicone in two sittings?!

Postby PAULPAUL » Sun Feb 19, 2012 11:15 pm

Hello

I was browsing around, looking for some knowledgeable folks, and found this place!

Can you help?

I am concerned with a step in my mold making process right now.

Part A of my two part silicone mold has cured, and has had 2 coats (with drying time) of Stoner Rapid Release agent applied, as well as Vaseline in the 'keys'.

I started pouring Part B of the silicone, but lost track of time (the studio I work at has a closing time), so did not cover all areas with silicone.

My question is:

Can I just apply more silicone to the uncovered areas tomorrow?

I am worried that the release agent may 'go off', or not work anymore due to time/whatever, and that Part A and B will bind.

Can you recommend anything, or relieve my worries?

Many thanks,

Paul
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Re: Pouring Part B silicone in two sittings?!

Postby Anvils Hammer » Mon Feb 20, 2012 2:18 am

Im not an expert on release agents, but I highly doubt it will stop being effective in only a day or two.

For added peace of mind, why not dilute a bit of vaseline with white spirit (I think thats whats reccomended on here, Paulson??) and carefully paint it onto the exposed A side?

AH
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Re: Pouring Part B silicone in two sittings?!

Postby blind pig » Mon Feb 20, 2012 10:57 am

You were using an RTV (Room Temperature Vulcanization) silicone, yeah?

If so, no problem. The silicone will stick to itself and that mould release should still work.

Don't try and spray any more release agent onto Side A, as you may get it on the partially poured Part B and then when you went to pour the rest of the Part B, you would get a de-lamination of the Part B side of your mould.

You did cover the mould box to stop dust getting onto the Part B side, didn't you? ;)
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Re: Pouring Part B silicone in two sittings?!

Postby mangozac » Mon Feb 20, 2012 11:38 am

Yeah it'll be fine. If the workshop is particularly dusty and you didn't cover it I'd use a clean, lint-free rag to wipe it off the initial areas of the part B pour to make sure it doesn't prevent the fresh stuff from bonding with it. As for the sprayed on mould release and vaseline there will be no problem there. I too would strongly advise against spraying any more mould release as it would be too easy to get it onto the already poured part B silicone.

Good luck!

Can you tell us what you're moulding?
Oh yeah I can make that....
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Re: Pouring Part B silicone in two sittings?!

Postby PAULPAUL » Mon Feb 20, 2012 10:08 pm

Thank you all very much.

I went ahead and poured the rest of Part B, having some piece of mind after reading your comments and talking to some other folks.

I am making a mold of the base of a stainless steel kitchen stool. I am onto Part 3 of what is shaping up to be a 6 part silicone mold. Definitely my most ambitious mold to date.

I have already molded and cast the cushion that sits on top.

Thanks again!
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Re: Pouring Part B silicone in two sittings?!

Postby mangozac » Tue Feb 21, 2012 7:08 am

Wow now that's certainly something a bit different from the usual stuff we're moulding around here!

Glad we could be of help!
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