Casting Your Own Bits (for the Terminally Hard of Thinking)

[Caerban]

I'm sculpting something. I'm not a putty genius like many of you (and of course the FoD owners). I make a lot of mistakes.
The something I'm sculpting is a dragon head for my girlfriend's birthday. I've more or less worked it into a rough skull, but now I've reached that paranoia stage where I worry everything I do now could make a big mess of it. So what I'd like to do is make a couple of resin casts and build the musculature onto them. That way if it goes wrong I've got spares.
But where to start that's the question? So I'm looking for advice. What am I going to need? How much? Where from (I'm in the UK)?
From scanning the interwhooojits and finding tutorials on what to do, I think I can work out roughly what I need to do to make the cast, the method I'm okay on (although I'm not going to complain if you want to spell it out for me again). My problem is the correct materials to use.
I perused the thread from Agentmolar's excellent tute on casting your own bases and checked out some of the sites mentioned, ending up with a brain bursting with a zillion different types of silicon for mould making and resin for casting. So please ease my addled mind and give me some pointers on the very basics. Assume no knowledge of the subject and only rudimentary, lizard-like intelligence :)

[Squigface]

www.tiranti.com sells casting stuff in the UK.

Squig

[Dr.Evil]

http://www.hirstarts.com/moldmake/moldmaking.html

[geronimo]

www.tiranti.com sells casting stuff in the UK.

Squig

Tiranti are far and away THE most expensive place to buy casting materials from. Especially if you;re just starting out, as you WILL make mistakes. An expensive way to learn :/

Try and eBay search, something like http://cgi.ebay.co.uk/RTV-Silicone-Mould-Making-Rubber-0-5kg_W0QQitemZ220203743673QQihZ012QQcategoryZ75576QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem would seem to do the job.  We use http://www.mouldlife.co.uk/ but their webshop isn't properly setup yet - they're mainly an industrial supplier who are starting to make inroads into hobby supply. As an example - Tiranti would charge around 3-6 times the price for an equivalent amount of rubber from Mouldlife.

If I could sort out suitably posting-proof small containers I'd let you have the relevant bits (it's illegal to send via standard post, which is why you'll pay more for courier delivery). If you're not in a desperate hurry I could make the mould and castings for you. PM me if you're interested :)

EDIT Oh and while I remember - anyone wanting to learn about casting could do a lot worse than treating themselves to this dvd http://cgi.ebay.co.uk/DVD-Making-Silicone-Rubber-Molds-Casting-Resin-Parts_W0QQitemZ360036977471QQihZ023QQcategoryZ19127QQrdZ1QQssPageNameZWD2VQQcmdZViewItem?_trksid=p1638.m122     
- watching a video is always easier to understand than following directions in a book. Though a lot of it is aimed at industrial-level casting techniques, there's more than enough there for the hobbyist to learn advanced basics. I llearnt new stuff from the earlier edition and I've been casting for over 20 years :)

[Agentmolar]

Thanks for the plug!


essentially i would recommend a silicone that is 1:1 mixing ratio> it makes it less of a headache to mix and pour. Some of them are by weight which means a calculator and a set of measuring scales.

As for casting resin, aim for a 1:1 as well for the same reasons. Try using a slower setting one first purely so you have working time to get used to using the material. As you get better at getting rid of air bubbles you can move to faster setting one.

www.trylon.co.uk
they have alginate there , which is excellent if you want an immediate pour and throw away mould.. Its the same as what i use in dental practice. Great for a one off master mould
Silicone is better for repouring.

[geronimo]

Thanks for the plug!


essentially i would recommend a silicone that is 1:1 mixing ratio> it makes it less of a headache to mix and pour. Some of them are by weight which means a calculator and a set of measuring scales.

As for casting resin, aim for a 1:1 as well for the same reasons. Try using a slower setting one first purely so you have working time to get used to using the material. As you get better at getting rid of air bubbles you can move to faster setting one.

www.trylon.co.uk
they have alginate there , which is excellent if you want an immediate pour and throw away mould.. Its the same as what i use in dental practice. Great for a one off master mould
Silicone is better for repouring.

Alginate would do the job on a very cheap basis - cheap enough to make two or three throwaway moulds. It's the stuff you always see in FX making-of dvds where they lifecast some actor's face/chest/whatever. The minty freshness of it is down to it's original use as AM says :D

Another option would be Siligum http://www.craftcellar.co.uk/index1.html?target=d288_moulding_casting.html&gclid=CMTN_ZGgyJICFRo71AodS1tWbw 50/50 silicone putty that you mix in your fingers,sets in 10 minutes, good enough for half a dozen casts. Most art shops should sell it...

[Agentmolar]

most silicone puttys are pretty ordinary with the detail. I prefer a flowable silicone.

[geronimo]

most silicone puttys are pretty ordinary with the detail. I prefer a flowable silicone.

Siligum's pretty good, if you use it properly - and far less expensive/messy/difficult to use for a first timer.

But yeah, pourable silicone's always going to give a better result.

[weirdwolf]

Hi Caerban, don't buy from Tiranti's, it'll cost you a arm & a leg. The cheapest I've found in the UK is www.tomps.com

Their RTV is some of the best I've worked with & the resin has great air release. Give them a shout you'll find them very helpful.

[Caerban]

Got my stuff from TOMPS and it is very good. The resin is nice too and conveniently skull coloured when dry. The casts I've made are far from perfect but suitable for my needs. My major problem has been the teeth. The angle and narrowness of them mean they won't fill with resin. This isn't a problem for me, I'll just make some new ones for the casts but if the skull resurfaces as a more commercial entity for those people who mentioned wanting one I'm going to have to rework them in a more chunky style and remould.
On the down side, lovely though the resin is, the only one they had was a fast set and you have to work like lightning.

[Agentmolar]

Im trying a new silicone today. Its a high temp one so  you can cast in metal or resin. I was advised that it will last against resin better due to the high temp range.

takes 24 hours to set.. so patience is a virtue. I highly recommend the 1:1 mixing silicones. the 10:1 ones ive used are a pain in the ass.

[Caerban]

The silicon I've got is a 20:1 and it is a pain in the ass. Particularly as my scales aren't the greatest. I'm having to round things to the nearest gram and hope for the best.

[geronimo]

The silicon I've got is a 20:1 and it is a pain in the ass. Particularly as my scales aren't the greatest. I'm having to round things to the nearest gram and hope for the best.

Hehe it depends what you're used to,I guess. We use about 15-20 different silicones and twice that many different resins - each suitable to a particular type of job.

One of the silicones has a mix ratio of 100:8:1 - try working that out without a set of decent digital scales :P