Need some help with casting...

[VonDoom]

I am making a decent size bust of Logan out of Roma plastilina(sulfur rich) and I want to make a temporary cast of it in Castilene so that I can work on the details more easily.

Then I want to make a more permanent cast that can be used to make molds of it at a later date if anyone is interested.



What material should I use to make a quick temporary mold and then the more permanent mold and cast?

Cheaper alternative would be best.. I don't have a lot of cash right now..

This is the sculpt in progress.. the neck will come down into a base --

http://img.photobucket.com/albums/v221/Dr.Gonzo1138/Hair1.jpg

[Andy Bergholtz]

One word--- ALGINATE.


This stuff works well:

http://azbrowax.com/catalog_98/RUBBERS/moldgel.htm


For doing 'waste' molds (molds intended to cast wax/castilene into for further working), you can't beat alginate, it works great and it's very economical. Also, you never need to use a mold release with alginate (which you would need if you used silicone since the Roma is sulfur rich).

For the final mold I'd suggest an RTV silicone (something like GI-1000 from Silicones Inc). You won't need to use any kind of release on your castilene sculpt before molding, silicone can be poured directly onto wax or castilene.

[VonDoom]

Thanks so much, Hulkfan! That's exactly the info I was looking for!

Can you get this stuff from your local art stores or do you need to order it?

[Andy Bergholtz]

No problemo. :)

I haven't found that particular brand of alginate locally, but you might get lucky. I would recommend staying away from the alginates that local hobby stores offer, they are usually not the highest quality (and not priced very well either). Your best bet for price and quality would be to order a good brand from the net, such as the above link. That particular brand has worked well for me... It's nice and strong (for an alginate) and should yield a detailed casting.

Casting castilene into alginate can be tricky... I suggest you take a trial run with a smaller object first, just to get the hang of both materials. If you brush or apply your alginate by hand, you'll need to back it with a support such as plaster bandages. Or if your sculpt is small enough you can even try building a box mold and pouring it in just like you would with silicone. When the alginate is cured, remove the original sculpt and pat the inside of the mold dry with a paper towel, make sure to get all the water out of the nooks & crannies. Then, nuke your Casilene (in 1-minute intervals, keep a close eye on it so it doesn't boil too much and burn). When the castilene is melted and bubbling, it's ready.... Stir it up really well (the bubbling will go down) and pour it into your mold. Let the mold sit for several hours (you can even put it in your fridge to help speed up the cooling) before demolding. You'll definitley notice some shrinkage in you casting, this is inevitable when casting any kind of wax into a mold. But, it should work for ya.

Good luck!

[VonDoom]

Great info!

Do you recommend getting that mixer thing they say to get on there?

Also, this sculpt is pretty big.. and I don't know if I have quite enough castilene to make a solid cast.. is it possible to fill the mold with castilene by pouring some in, rolling it around and creating a shell?

[Andy Bergholtz]

Actually I would recommend getting a mixer like that... It just sticks into an electric drill. It's not 100% necessary but makes for MUCH more efficient (and fast) mixing. Just beware that using one of those mixers tends to 'whip' a lot of air into the alginate, so there will be small bubbles to contend with.

As for the slush-casting, I don't see why that wouldn't work with the castilene. You might want to fill it with another material though before de-molding (maybe plaster or something, just so the castilene 'shell' doesn't crumble on you...?).

[VonDoom]

Can't thank you enough for all the great info, Hulkfan. Hopefully someday I will be a good sculptor and making some cash and I will give you a free sculpt of anything you want. :)

[Monkey]

If you have questions concerning casting you can contact Mark at earthboundstudios@yahoo.com .He's always been very helpful when I have questions.

Monkey
www.modelmonkeys.com

[Model Giants]

Mark is the Zen Master of casting.

Paul