I have only read about it, but never used it.  It is made from seaweed and originally used for dental and prosthetic castings/molds, and is one of the few materials that is safe to use directly on skin.  The Jacquard name brand costs about $4 per (dry) ounce, but some craft brands are much less expensive.

It is said to be extremely flexible, but it won't hold its shape on its own, and will need support (such as a plaster base).  Also, it doesn't last very long (a few days), and doesn't make many copies.  But if you are doing molds of faces, hands or feet, it is safe to use, which cannot be said of plaster. 

NEVER USE MIXED PLASTER DIRECTLY ON A LIVING CREATURE for this purpose -- the burns can be horrific and can lead to the loss of body parts!  The only safe plaster to use directly on live body parts is the kind embedded in cloth bandage material, the stuff used for making casts when you break your arm or leg.

Here is some info on Alginate that I have in my bookmarks:

Basic information:  http://www.modroc.com/chromatic-impress … -alginate/

All About Alginate:  http://www.maragon.co.uk/alginate.html

How to Cast a Face in Plaster (w/photos):  http://www.instructables.com/id/How-To- … /?ALLSTEPS

If anyone uses it, please post back here and tell us all about it, the good and the bad!

Sue

Ah... the memories!  ;-)

Sue

Well.I tried the alginate,it holds very good detail,but the mould broke in half
as soon as I touched it!stuck it together but not very successful.
Thanks everyone.
Sarah.