Alginate question

[Ramirez]

Apologies if this isn't the right place to ask:

I want to make a cast of my hand for a project, using alginate for the mould.

I've never used alginate before, can i pour plastic/resin into the mould or do i need to make a preliminary cast from plaster, seal it, make a new mould from silicone and then cast it in resin?

 

[Mutant-Enemy]

I've never tried pouring a plastic/resin into alginate...
It seems like a plaster positive would be easier to clean up for another mold however.
Best I could tell you would be to go the usual route and pour up in plaster or Ultra-Cal and work off of that.
I highly recomend "Body Double" from Smooth-on though for your next body part replication.
It's a silicone that can be brushed directly onto the skin.
If you make your mold strong enough and use a good mother-mold with it you can pour up almost as many duplicates as you want in almost any medium (except latex).
Good luck!

 

[SUPERprops]

If it's the stuff from smooth-on then(from what i've heard) YES you can.

 

[Bondo Fett]

Apologies if this isn't the right place to ask:

I want to make a cast of my hand for a project, using alginate for the mould.

I've never used alginate before, can i pour plastic/resin into the mould or do i need to make a preliminary cast from plaster, seal it, make a new mould from silicone and then cast it in resin?

Alginate is inexpensive and easy to use for first-timers. Any decent art-supply store should carry it. Use a medium-sized paint bucket and add the alginate powder to luke-warm water until it is nice and thick. Just mix it with the hand you mean to cast and squish the stuff around really good to burp out any air bubbles. Let it set up like stiff Jell-O. To de-mold you'll have to slowly and gently flex your hand to avoid tearing the alginate (it is pretty fragile stuff). Once you have started to let some air into the casting you should be able to get your hand out of the mold. For the positive you should use Ultracal, since it is very hard, but regular pottery plaster will work, too. Mix it up to smooth, soupy consistency and pour it in slowly, rolling the mold around a little bit to get any trapped air out. A couple of slaps on the side of the mold will help, too. When its set you just tear the alginate away from your casting. The major drawback is that alginate is a one-time use material- you get one shot at making one usable positive. But its cheap and easy to use, so give it a rip! I'd recommend plaster for the positive since you'll probably want to fix some little flaws and such that inevitably result from the casting process, also its not as finicky as resin. I hope you find this helpful.

 

[Ramirez]

Thanks for the advice guys.

Btw, i always use Vyta-Flex 20 for moulds and Smooth-Cast 300 for casting.

 

[IEDBOUNTYHUNTER]

here check this out, it should be helpful.


Alja-Safe® Lifecasting Quick Start Guide | Smooth-On

Al

 

[REL]

I agree with everything Bondo Fett said, only this time of year I would use cold water instead of luke warm with the alginate as it sets up pretty fast and you may run out of time.

You can get it at dental supply places too, I like the cinnamon flavor, LOL.

 

[SwampDonkey]

The 2-part resin sold as Aluma-lite works well with alginate. Its all about fast cure times and that stuff turns to rock-hard plastic in about 5 mins.

 

[Mostly Fantasy]

Usually, alginate, being a water based material, will interfere with urethane resins, if only a little bit. I'd use wax, and then clean it up, and make a permanent silicone mold. Another option is to use a biocompatible/skin friendly silicone to make your negative, then go with urethane casting.