a good tut on how to make a cheap mold from caulk

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I used this method for my Slave Leia resin and fibreglass parts as well as my Samara (Mass Effect 2) collar piece. I made a tutorial for the local costplayers in NZ over here:
http://cosplaynewzealand.forumotion...ique-f31/budget-molding-and-casting-t9028.htm

For me it really saved about 66% of molding costs as molding silicon here is very expensive. Even with caulking tubes at between $NZ13-20 a tube (about 500gm or just shy of 1lb) it worked out much cheaper.
Also when you use condensation cured silicon and use the soapy water method you have a heck of a lot of control over where the silicon goes.

As mentioned in my tutorial urethane resin really does make the silicon quite brittle/dry but epoxy seems to be fine. I did press bondo into some molds and it was ok so polyester resin will also be ok. It did make the molds stink. I mean really stink. The smell lasted for a very long time.

I made jackets of plaster to support the silicon and when it came to the complex curves of the Leia bikini top I mixed a paste of epoxy resin and fairing powder and painted that into the molds. Meanwhile I had some matting soaking in some more resin and when it reached the gelly stage I mixed some more fairing powder in and pressed that into the mold and then wrapped the whole thing around my mannequin (which was covered in glad wrap).

I used cooking oil spray as my mold release- worked very well on the plasticine but I should have used a bit more on the plastic parts and also something a bit more solid than liquid on a few metal parts.

I did find it worked best with the translucent stuff and really badly with some black roofing silicon. That just never really cured all the way through. Not sure if there was some reaction with the pigments in it or I just had a bad batch.
 
for those worried about strength i would suggest adding some cheese cloth between your first and second layers.. doing so will help add strength to the silicone so it won't tear when you are casting helmets and such
 
Hey, what's cheese cloth?
I was going to say that I am totally gonna use this method to cast a bunch of HD ODST helmets and sell them on Ebay
And yes, I am going to make my own casts out of my own ODST helmet which I am going to make myself. I also might mold Carter, Jorge, Jun, Emile and N6 helmets to sell, at a reasonable price of course
 
Cheese cloth is a very loosely woven cotton fabric. You may see it labeled as muslin in some places (though in the US that usually refers to a non-printed calico). It's very think and as its name suggests is used in making cheeses (the curds are poured into a mold lined with it and strained- hense the loose weave to let the liquids out quickly).

I'm about to break out this technique again for my own helmet (bounty hunter from The Old Republic) so I may be able to post some photos of that :)
 
hey instead of using smoothon plastic for the mold could i pour fiberglass resin in the mold ?? if so that would be just awesome !!!
 
My helmet:
th_sm_P1080084.jpg th_sm_P1080085.jpg th_sm_P1080086.jpg

Making the mold:
th_sm_P1080088.jpg th_sm_P1080089.jpg
Budget silicon mold making- warm water with lots of detergent, squirt caulking* smoosh in hands and then onto sculpt:
th_sm_P1080087.jpg th_sm_P1080090.jpg

I like this method as there is just enough tack in the silicon to adhere to the sculpt and it doesn't slump when you apply it to the vertical and even underhanging surfaces. I put on a layer of about 7mm and if I want to make a more permanent mold I'll repeat that the next day. I want to make some of my jacketed molds single silicon molds for ease of storage too.

The key though is to make sure your hands and wrists are soapy too. You wind up with wrinkled bath hands but it helps with smoothing the mold and keeping it all even.

Those knobs act as keys for when I put on a fibreglass jacket to keep the mold rigid. This helmet is shaped nicely so I can have a one part jacket as well but for a more complicated helmet it would be possible to make the jacket two parts to bolt together to allow the silicon to pull off the mold. It does stretch a bit to allow for getting out of those undercuts. More complicated may require two stage for the silicon too.

I would be careful of the type of resin you use- urethane nearly killed my Leia molds (they felt brittle after and it seemed to stick more) expoxy is fine, polyester will make the silicon stink for a very long time. Make sure also to wash and dry the molds and use a mold release that works with your resin.

This just stage one of my helmet so I'm doing a really budget mold hense the thin layer (though it is four tubes of caulking- not sure if they are the same size as you get in other countries) and the FG jacket will be minimal too as it'll be used once maybe twice if I goof. The next stage will be to slush my own epoxy putty mix in there and back fill with urethane foam so I can do the detail work.

Oh yeah, the helmet is the female Bounty Hunter from Star Wars the Old Republic :)

*I only cut the end off the tube as the more surface area of the silicon exposed to water the better as it is condensation- ie water- cured. But you can cut the tube end totally off for getting the silicon in the water faster.
 
So you mix the water w/ detergent with the caulk. And that makes it that sloppy guppy :) type substance that makes it easier to apply it to the sculpture? Also i believe that cooking oil might be a good substitute for the release agent. I will try it and let you know!
 
might give this one a try on something simple like a hand plate or something... is there an issue with flexing of the mold, or did you make a plaster/fibreglass back to support it?
 
This is the method that I have been using to produce my first set of armor and it has worked out quite well for me so far. I'm using plaster of paris to support the negative mold.
 
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