Goop in Silicon (RTV) molds?

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Goop in Silicon (RTV) molds?

Postby Archives » Sun Nov 08, 2009 10:14 pm

Suntzu
Registered: 12/24/06
Posts: 2
12/24/06 at 06:04 AM
Reply with quote #1

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Hi! Ive come across this forum in the past but recently ive finally succumbed to the urge of all things Goop after reviewing the Fighting Men Mattel set. Ive been creating action figures (using joints E.G. GI JOE, Star Wars, etc... sculpt, mold, cast, assemble, etc. etc.) for years now and ive always found it frustrating that most "bend ems" or bendable figures simple didnt look as impressive as they could have :-) Only 2 lines have been able to pull off the well (enough) detailed rubber over wire look: Jakks Pacific WWE Flex'Ems wrestling figures and the vintage Mattel Fighting Men.

My question: Id really like to avoid making metal molds in order to make 2 sided , wire armature bendable figures. The only way to do this quickly and efficiently would be to use Goop in one of my own molds ( of which i have plenty lol..) with a wire armature suspended in the middle like the Mattel Fighting men molds. The problem is after reading many threads here i recall "Joseph" mentioning that the RTV molds were such great insulators that the goop didnt cure in them.

IS this true? IS there any way around this? Has anyone else tried this?

Id really like to get into using the goop to make my own custom figures (bendable that is. That vital to me) using my molds but if i must use metal molds that may stop me from using goop at all.

Help?

And Happy Holidays... :-)


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Re: Goop in Silicon (RTV) molds?

Postby Archives » Sun Nov 08, 2009 10:15 pm

dr_goop


Registered: 01/21/06
Posts: 44
12/25/06 at 10:46 PM
Reply with quote #2

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I have two bits of info to offer. First, I do know of someone who has successfully used RTV silicone as molds for goop/PVC resin. It required using a very thin goop that was pourable when hot. He would heat up the goop in a pan or microwave, and because it had a lot of plasticizer, he was able to pour it into a RTV silicone mold.



Second bit of info. Some 2 part silicones use organometallic catalysts that seem to react with goop. The result is that the goop is catalytically dehydrochlorinated and you will see lots of bubbles on the contact surface of the goop.



Please do keep us updated on your endeavour.

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Re: Goop in Silicon (RTV) molds?

Postby Archives » Sun Nov 08, 2009 10:16 pm

Suntzu
Registered: 12/24/06
Posts: 2
12/26/06 at 04:48 AM
Reply with quote #3

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Hi!

Thank you for your response. Ive been actively researching information so every little bit helps.

Another question for you....has anyone ever used actual resin molds (molds made of hard resin) ? Id assume if the heat required (345 for example) was only needed for a few minutes (how long does goop need to bake...3 minutes? 5 minutes?) then the resin molds should hold up (at least for a few runs).

Thoughts?


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Re: Goop in Silicon (RTV) molds?

Postby Archives » Sun Nov 08, 2009 10:16 pm

dr_goop


Registered: 01/21/06
Posts: 44
12/27/06 at 11:05 PM
Reply with quote #4

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I think the problem you will run into is that most resins will not stand up to the heating and will act as insulators as you mentioned before. Pouring hot highly plasticized pvc is the only way I know around this. There is a heat rated construction grade RTV silicone that is used for fire barriers. I think it is stable up to around 450-500 F but I have never used it.



I don't know how much detail you need but you might be able to make a mold by placing some aluminum foil over the item and vacuforming. Then before removing the foil fill the back with plaster or balled up foil for support. Never tried that either.



It just came to me that I have heard of people loading 2 part resins with aluminum powder. If you took it to the limit the mold might hold up and transfer the heat.

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Re: Goop in Silicon (RTV) molds?

Postby Archives » Sun Nov 08, 2009 10:17 pm

omnichi
Registered: 08/10/06
Posts: 85
01/05/07 at 03:01 AM
Reply with quote #5

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Hi,

Joseph here, back from vacation. I use a RTV silicone rubber made by the Castolite Company. It doesn't need to be heat cured. You just add a hardener and it sets up in 24 hours. I use the type Castolite calls Castomold-HT which can withstand multiple castings (100s) of molten tin or pewter (500-600 farhenheit). You could use this rubber to make molds for your army men, but I think you would have to pour molten Goop into it like Dr. Goop suggested. I have used this silicone rubber to make molds of tin soldiers for the last twenty years. There are two companies I know of that sell silicone rubber molds already prepared which you can use to cast pewter or tin soldiers.

Another way: I am still working on just one piece metal molds, but it is not a huge stretch to make a two piece metal mold. I've been making two piece rubber molds for twenty years and it would be essentially the same process.

If you are interested in learning more about tin soldiers, let me know here and I'll pass along the names of the companies that make the silicone molds.

I will also be happy to share my mold making "secrets" if you want to try to make your own metal molds. I know it sounds a little intimidating, but I found that it can be done with practice.

Good luck in your endeavors!

Joseph

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Re: Goop in Silicon (RTV) molds?

Postby Archives » Sun Nov 08, 2009 10:18 pm

omnichi
Registered: 08/10/06
Posts: 85
01/05/07 at 01:38 PM
Reply with quote #6

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Hi again,

I just remembered that the Castolite company makes a casting plastic called Castosil. It is very similar to Goop, but you cook it externally and pour it into a mold. I tried it back in the days before Dr. Goop and it sort of worked in the Thingmaker molds. I didn't try it with silicone rubber molds (the Castolite Company's suggested use of Castosil), but that might work for your needs as well.

Joseph


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