alginate and life casting, am I doing something wrong?

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sn2getaway

New Member
I am so glad I found (and by found, I mean told about) this place!

I attempted my first life casting project last night and I have to say, it's not as easy as it looks. Instead of a whole head, I ended up just doing a face because I'm not familiar with this practice at all. While it turned out ok, I have some questions about alginate.

Is the final product supposed to produce a thin layer of liquid? I noticed that my final mold was "sweating" when I was done with it and even the left over throw away pieces seemed the produce a pool of water. Is this normal or did I mix the alginate and water incorrectly? Also, I know this is a fast moving process, but when you are applying the plaster bandages for reinforcement, is the alginate supposed to still be sticky? I think I waited too long before going to the plaster stage. When I removed the cast from my friends face, the plaster came off by itself and then I had to peel the alginate off of her. Didn't make for a perfect cast at all.

Thanks in advance for the help!
 

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pitchforknumb

Sr Member
Alginate has Its quarks to work out. As soon as it sets up it will start evaporating and make the pools you are talking about. That's just the way alginate is. You can try sealing it with Crystal clear but I've never found that to be helpful. Also nothing sticks to alginate not even alginate. If you want the plaster bandages to stay attached to the alginate you'll need to embed some cotton into the alginate so the bandages have something to grab onto.
 

sn2getaway

New Member
Thanks for the heads up. I did that, but the cotton didn't stick too well. Like I said, I think I took too long to get to that point. Ah well. Practice makes perfect.
 

Mr Mold Maker

Sr Member
. Also nothing sticks to alginate not even alginate. .

Pitchforknumb absolutely has it right, just one thing I thought I'd throw out. You can take some windex on a swab and very carefully apply some to where you want to add fresh alginate and it will stick to itself. I don't recommend it for lifecasts, but when pulling snaps for example, it's great info to know.
 

cunningham

Active Member
I think the alginate material is made from seaweed or some derivative of it ( at least the blue stuff I have is), so it will sweat constantly. Because it sweats water, you have to use plaster bandages or something water based to reinforce it until you cast with it. I have only used Ultracal 30 to cast with this stuff, as it is water based and sets quickly in the alginate, as opposed to using a resin material, which would react badly to the water weeping from the alginate.

Alginate on its own is pretty floppy and useless until you use the bandages as a mother mold to keep its shape. I would think doing an entire head would be very difficult, as I have only had success with smaller areas such as a face or an entire hand.
 

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pitchforknumb

Sr Member
Usually when I do an entire head cast I just use plaster bandages on the back half of the head and then use the alginate plaster bandage combo on the front half.
 

Philly

Sr Member
RPF PREMIUM MEMBER
Before the alginate sets dab on some cotton wool, it will give the plaster something to grab on to :)
 

sn2getaway

New Member
Here's my next question, sorry if it's been asked before or is just a dumb question, but how does one do a full head successfully? I'm confused as to how you would get the person out lol
 

Mr Mold Maker

Sr Member
Here's my next question, sorry if it's been asked before or is just a dumb question, but how does one do a full head successfully? I'm confused as to how you would get the person out lol
Two piece plaster bandage jacket split down the center of the head, and cut up the back of the alginate until you can pull it off like a mask.
Here is a good video demo with silicone. https://www.youtube.com/watch?v=SSNgdML7XBM
 

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