Friday, 23 October 2009

Latex diaries part 1

Well, the past few days I have been teaching myself how to make molds and also I have been failing miserably at using foam latex.

Making the molds was fairly successful. I started by making an arm out of super sculpy and baked it for a little while.

For the mold, I started of with a bed of clay then built it up to half way around the arm. I inserted marbles in to the clay for keys so the mold could line up perfectly and I also put in some cocktail sticks to form channels for the foam in the casting process.

I then made a wall out of cardboard around the clay and filled in any spaces between the card and the clay bed, so the plaster wouldn't leak.

The plaster I use is Crystacal R it's a very hard plaster and drys pretty much like stone and gives your mold a good life span. It hardens and cures within hours.

After the plaster had set, I turned the mold over and picked out the clay. I had to do this fairly quickly as the clay I had used was air drying and wasn't sure how long it took to harden. The first half was a success. There was no air bubbles and everything had been cast properly.

I then built a new wall of cardboard around the mold and repeated the process for the second half. Also I put a light coating of Vaseline on the mold around the arm so when the second half had set the two would separate better.


Then it was time for my first foam latex experiment, which was a complete and utter disaster. After a few attempts I think It's not really a latex but just foam.

The foam I am trying to use is Polyurethane Expanding Foam Sometimes called cold foam.
The first test was just horrendously bad. After pouring each part of the foam, I started mixing, looked away for a moment then looked back too see the cup I was mixing in completely overflowing with foam. I panicked and threw some into my molds an quickly placed the arms armature in, slapped the two half's together and stood back to overlook the chaos. There was foam everywhere! I waited for about 20 minutes, whilst prodding bits of foam on the table to see if it had cured. When it was done I cut the mold from the sea of foam around it and pulled the two half's apart. It came out ok but was far too thin on the under side of the arm. Also there was a lot of bubbles in the foam. It just didn't look how I wanted it too and the seam on it was unrepairable.
I think I used far too much mix and got the amount of each very very wrong.

The second try was a bit better to start with. I used less than half the amount of mix then the first time. I also added some flesh coloured pigment to it. The mixing weent well, it looked right and poured into the mold perfectly. It still made a big mess!
I did the same as before, I waited for it too cure whilst prodding bits that had fallen on the table. But this time I noticed the foam was just smearing and crumbling.It took me 10 minutes to split the mold apart. The arm had been cast ok but as soon as I picked it out it just crumbled apart. So another failure but also a lesson learned. I also found out after this second test that the pigment I have bought is for latex not for polyurethane foam.

I thought I would also include a photo of the two cups I mixed the foam in comparing
the outcome of the two try's. The cup on right is completely dry and feels like a cushion!

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