9.06.2007

Alginate & My Crazy Theory

Alginate is used to make molds, most commonly in lifecasting, on people's parts. I get it in powder form, and mix with water until its a bit like peanut butter. Its applied to the area to be molded, lets say, my wifes face, and it slides. Droops down, has to constantly be monitored, and finagled, and reapplied, until its set, about 20 minutes or so. Its a racing game, like with foam latex, to get it where you want it before it sets. About halfway through, when it just begins to set up, I apply strips of terrycloth, which provide grab-on points for the plaster bandage mother mold. The plaster shell will keep the alginate in position, because it sets up sort of floppy, like rubber latex without the tensile strength. Once it sets its ready to be used. Now here's the cool thing......you can pour in plaster or melted clay.....hard cast (plaster) would result in a soft mold (latex), or soft cast(clay) to hard mold (ultracal), then to foam latex, for example.
The alginate will start to dry out quickly, but you can store it in a bucket of water and it will be fine. I had my wife's face in a bucket for almost two months, took it out this week, stuck it back onto the plaster shell, and pulled a new clay copy out of it, which looks virtually the same as the original.
Then I got curious, and here's where the fun begins. I left the alginate mold out, didnt put it back in the water. Over the next day I watched it harden and SHRINK....it started to curl badly, so I stuck a little piece of dowel inside, from cheek to cheek, to keep it in shape, and now I have a miniature mold of the face. About half-size.
The clay mini-copy doesn't look great, because I wasn't thinking about what I was doing, and I poured the melted clay directly into the hardened alginate mold with no release agent, so it distorted some when pulling out. And you can see where I had to resculpt the nose a bit, around the nostrils, because I didn't put enough alginate in that area.
But here's the kicker....I take this clay mini-copy, make an alginate mold of it, and let that shrink.....should end up, oh I don't know.......about puppet size.......!!! Makes me think about a little 'self-puppet' idea I had, many moons ago....
Let me take it a step further.....suppose I need a smaller version of Jenny for a long shot in the 'Greenteeth' short....I could pull a rubber latex version from the Jenny mold (whenever the sculpt is done :D, then alginate-mold that, let it shrink, and pull a new teeny Jenny from the dried mold...possible? We'll just have to wait and see.....Requires further study.......

7 comments:

Darkstrider said...

Thwere's a product called Hydroshrink that does that, but without the distortion (which actually could be pretty cool though!). There's also a Hydrospan to enlarge things. Similar to the technique of soaking a silicone casting in naptha or whatever it is, which is measy and gross and really stinky. Worth considering anyway. Unless of course you want to just use alginate; ')

Ubatuber said...

Schweet! Never heard of the stuff, looks much easier than my technique :)

Shelley Noble said...

Wooo. Me likee. What a fun idea to have multis of a sculpt w/o having to match by hand.

I vote for alginate, cuz it's non-tox compared to the other products, right?

What are you going to do with Lady Roche?!

Shelley Noble said...

Caught up now, gotcha! Cool beans project.

Sven Bonnichsen said...

I've heard of this hydroshrink stuff before... It gets some use in the toy industry -- so folks can sculpt a large prototype of an action figure (etc) and then shrink it down.

thediamondmaker said...

I've never heard of pouring melted clay in alginate before, that's sweet! What type of clay do you use and how do you do it?

UbaTuber said...

I use Van Aken clay, oil-based...melt it in a pot over low heat...you'll need to make sure you have a plaster mother mold to hold your alginate's shape, then pour the clay into the alginate, easy-peasy! You'll want to pour with one tip of the pot though, because if you stop pouring and start again, you'll start to get ridges in your casting, sort of like the rings in a tree trunk...

I hope this helps :) And welcome to the blog!!