We built an armature hand and then we sculpted over it using Plasticine, this was my first go so I did not use any detail or fingernails or skin texture. But next time if using this method I would trying it out.
We made a bed of clay and lay the Plasticine hand into it, so we had half of it covered. We then need to make sure the clay was completely smoothed out and pressed against the hand all the way around. we place a 'key' over the exposed K and S, this will help us remove the hand.
We drew a box around the hand leaving a few centimeters of space all the way around. Then we put a clay 'key' in each corner of the box. These 'keys' will that the two halves of your plaster mold will align perfectly. we cut off the excess clay around it.
We then need to make a box around our square of clay. We use plenty of glue gun to prevent the plaster leaking out of the box. Once the box was made we needed to use a thin sausage of clay to seal the edge between the clay and the box to prevent the plaster leaking.
Finally it is we put a layer of Vaseline onto the plastic box to prevent the plaster sticking to it.
This is the box I made, at this point I had just poured the first half of the plaster into the box. This particular plaster took about an hour to dry.
When the plaster has set we should end up with something similar to the photo to the side. Next we carefully pulled of clay away from the plaster making sure the hand sculpt stays in the plaster.
We cleaned it as much as possible to clean the clay off of the plaster and hand as possible.
We added need another key to the other half of the exposed k&s.The blocks of red Plasticine around the arm will create a space which will allow any excess latex to pour out when you come to casting.
Once again we put the box walls up around our mold and put some Vaseline on the plastic. Then pour in more Plaster and allow to dry.Once we plastered it and it has set, we un-box it.
We c removing any leftover clay and Plasticine from the plaster and making it clean and tidy before you cast any latex in it.