Continues from Part 1.
One of the prototype clay hands I used in the previous post (grey color – Super Sculpey) was broken during demolding, so back to the first pair of hands.
They are sculpted out of Super Sculpey Living Doll Polymer Clay over cotton Finger Wire and brass tubes and baked.
For details how they were made – Part 1. Here they are before improvement.
I cleaned them up, added clay – to improve the shape. Also, gave them a slightly different shape at the place where the hands will be connected to the soft body – a grove to tie the cotton thread or whatever I will use – around. Painted with liquid clay (translucent liquid sculpey), suspended with forceps and baked.
Ball-jointed armature: soft annealed 1mm aluminum wire and household cotton thread.
Wires go through the ball, then are curved and pushed down to level with the ball, as much as possible, then secured with J-B Weld Epoxy.
Lego Pieces for Molding Box (mounting board 24×24 dots, 196 pieces of square 2×2 dots blocks)
Plasticine Chavant Le Beau Touche Clay HM
Rib cutter blade
3.2mm wooden skewers to close the tubes openings.
It helps to warm the plasticine for a few minutes in the oven, it becomes spreadable with Rib cutter blade and I can press the hands down into the clay.
Add clay to the corners and go around the hands so that there are no undercuts (any indentation or protrusion in a shape that will prevent its withdrawal from the mold). Illustration of an undercut from Andrea Vinkovic ceramics tutorial:
I am using up what I have left of the casting compound. Ultracal 30 is on its way – for the next time.
1 cup of water, 2 cups of plaster makes about 1.5″ thick layer in this roughly 11 cm x 11 cm box.
Painted the first layer with a disposable brush. The brush gets ruined, so don’t use your good brushes.
Fill it up. How much? At least 1″ (25mm) thick. The second part of mold was less than that, about 0.5″ (13mm) – I used up the very last of my molding compound and it was not enough. It cracked when I was pressing two halves together. After I got the cured hands out that other half of the mold was in pieces.
Clean up traces of plasticine from the hands with orange oil and wash with water and soap and dry.
Second part of the mold. It did not quite fit back into the same size lego box so I had to enlarge the box by moving the wall of lego out and filling the gap with plasticine.
Bend the tips of the finger wires. My theory is that bending ends will prevent the armature from tearing into silicone and poking through.
Wrap in cotton thread so that silicone clings to it. It actually does, as I demolished one of the previous silicone hands to see what is going on inside – silicone does cling to the cotton-wrapped wire better and slides off easily from naked metal wire.
a few grams of naphtha (I am using Zippo lighting fluid while waiting for naphtha, it also works).
I don’t know exactly the amount, because I added it a few times while mixing to get the right consistency.
Naphtha (and Zippo) will thin the silicone so that I can paint with it.
Finally – 2 grams of Platsil Gel 10 Part B.
From this point – the clock is ticking, as silicone is curing pretty fast. The consistency starts to change after 6 minutes and it is cured completely within 30 minutes.
Mix all and paint the fingers to make “bones”. Quickly, as I said, there is not much time to be a perfectionist.
Suspended with forceps upside down – I need those rounded finger tips.
Mix another batch of silicone.
10 gram of Platsil Gel 10<img src=" Part A
1 gram of DecoArt acrylic paint Flesh.
10 grams of Platsil Gel 10 Part B
A bit of naphtha (a few drops).
Started to carefully fill up the mold and taking photos, but realized I am running out of curing time, so here is just one photo of this step.
– Starting from the fingers carefully paint the inside of the mold with a thin 1-2 mm layer of silicone.
– Press the armatures in their places.
– Fill the mold up to the brim, it is ok if appears that you put too much silicone.
– Put two parts of the mold together and press.
– Put 2 C-clamps on the mold and tighten. (I don’t have c-clamps yet, they are ordered and on their way. I pressed it with my hands and even stepped on the mold lightly. That was not a good idea, as one of the halves (thinner one) cracked. I left it alone to cure and got this pair of hands out, but that mold half is in pieces. The moral of the story – make thicker mold halves and use c-clamps).
Small scissors to trim.
Some abrasive material, in my case buffing sponge with lighting fluid, to buff the seams. Naphtha or vaseline will also work, they say.
Here is before and after:
Pros: The wrist joint is functioning well. The fingers bend and move. The grey shadow from the metal under the silicone is almost gone. The details are good, the color and translucency of the silicone are nice.
Cons: One of the joints is a bit too close to the skin. I have a strategy for the next time to prevent it – when painting the “bones”, I will also paint the inside of the mold in the wrist area.
There are a couple of bubbles – I think I will add more naphtha to the mix next time to make it a little bit more runny.
Also, I will make all 4 parts of the mold overflowing instead of to the brim. Pressing molds together pushes the silicone out and helps with bubbles.
Hands – again, with lessons learned
New mold – this time with Ultracal 30. Yes, it is definitely stronger than plaster of paris, holds the detail better.
J-B Weld Epoxy
Press flat and pinch with wire cutter to prevent the wires from being pulled out.
1.2 grams of Platsil Gel 10 Part B.
Intrinsic silicone painting:
This time I tried genesis paints<img src=" which are basically oil paints with concentrated pigment content content in a form of a paste. Concentrated means I only need an amount on the tip of the needle to color the batch I am working with.
It worked. So, in addition to acrylic paints – oil paints are an option.
Here is my face painting kit, it contains Burnt Umber (brown color), Genesis Red (red color), Carbon Black (black color), Genesis Flesh 08 (flesh color), Yellow Ochre (yellow color), Viridian Blue 01 (blue color)
0.5 gram of Platsil Gel 10 Part A,
Needle tip amount of Viridian Blue 01.
0.5 gram of Platsil Gel 10 Part B.
A tiny bit of naphtha to make runny.
Paint veins inside the mold.
Mixed Platsil Gel 10 with a bit of Genesis Red the same way and paint palms.
Added some white acrylic (a needle tip) to the remaining pink mix and painted fingernails (which I later I did not like).
Waited 30 minutes until cured.
Mixed a batch of Platsil with Decoart Flesh and painted thin layer of silicone (skin layer) inside the entire mold (forgot to take the photo, but you can it a little bit on the right photo just below. Skin layer allows to make sure that there are no bubbles on the surface.
Waited until that l
Pressed the armatures into the silicone, filled all 4 parts overflowing the brim.
Pressed the halves of the mold together and waited until cured.
Here they – looks good. The coloring can improved, but this is very close to what I wanted.
This pair of hands (attempt number 4) will stay, I am moving to the feet.
There is quite a learning curve, but I loved the result from the intrinsic silicone coloring and will continue to practice.
Continues on Part 3.