robalo01

Thinning silicone

11 posts in this topic

Is it possible to thin common household silicone with sillicone oil (used to thin RTV silicone) in order to pour it over a model for mold making?

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Anything other than a thin coat of regular one part silicone, is going to take forever to set.

Dave

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Anything other than a thin coat of regular one part silicone, is going to take forever to set.

Dave

are you sure ? there was a mouldmaking tutorial on this page before the crash with one part silicone

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Go to the Smooth-on site or get in contact with Del (Del-mart) from this site for the good stuff. The "water added" technique works with certain household type of sil, but it can be MEAN! Gives off a great deal of acid and you have to work pretty quickly before it starts to set up. I always got half-arse molds with it, lots of little pores and inconsistencies due to air/water pockets in the mold.

The blue stuff IS expensive, but it looks like the way to go for any level of quality. Always remember the learning curve with regard to price...you'll go through quite a bit of the household stuff learning how to use it and get a decent result. The expensive, pourable stuff is made for the purpose in your inquiry and likely will be alot easier and cost efficient in the long run.

Sometimes, trying to save money is a more expensive PIA...at least it has been for me at times.

http://www.del-mart.com/shop/home.php?cat=335

Edited by jrav
edited to find&post Del-Mart link for silicone/product advice

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The RTV I get here in Mexico is thinned with what they call "silicon oil". I have tried it but: either you pur it stight and it seta fast and is very tough and porous; or, you thinn it with the oil, it turns out a lovely mold that is s little more firm than jello. it won't hold it shape under the presure of expanding foam. So I've been making some molds with regular silicon activated with water.

I guess this is one I'll have to try myself. I'll let you know how it goes.

PS. What about pouring molds with PVC plastisol with a lot of hardener?

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You can thin down silicone with naptha but I dont know if you could get it thin enough to pour but if you are looking for something to hold up against the pressure from the foam you could cast your mold with silicone or rtv and then pour a support cast using plaster of paris or smooth-on 300

Mike

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How about making the mold with your soft silicone, then making a slave casting out of bondo, and then a mold of that out of bondo. Bondo is hard and tough, and if you make a shallow wood box, or can find a shallow plastic dish that's the right size, you should be able to make a mold that will last for lots of castings. depending on what you're casting with, use the appropriate release agent. The manuf. of your casting material should be able to steer you to the right releas agent.

And you'll have the bondo slave to make more molds if you need them.

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are you sure ? there was a mouldmaking tutorial on this page before the crash with one part silicone

The Slip Mold tutorial is a downloadable pdf file in the hard bait How-To forum. Thanks again CrawChuck for writing it.:yay:

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