To starting making the Krogan head I needed to make a base/foot om my face cast, and since I knew that the weight of sculpting and mold making could reach up to 50 kg, I added some wheels om my sculpting table so turning my work would be easier. I had to make my face cast steady so I made a plaster wall on the bottom part (as shown in the picture to the right), and I sprayed the plaster and wood board with clear lack for sealing it to not soak up the water from my water clay.
I was now ready to start my sculpting. I used 50 kg water clay and sculpted it in 3 days, during which I took over 50 pictures compiled in a short video (see the sculpting video in the menu).
I sculpted with blanks of the eyeballs in it (shown further down). I followed reference pictures, to help get an overview while blocking out the big shape of the head, and to keep track of where my (the model) mouth and eyes are I used some wood sticks (shown in the pictures in the video). After finishing up the sculpting, I sealed the clay with clear spray paint (shown in the 3 pictures below).
Silicone and fiberglass outershell
All silicone and fiberglass processes for this project are done the same way, I will describe all of it here and refer to this paragraph when I'm explaining other parts of the build further down in this tutorial.
First I had to make dividing walls with keys (made in clay, look at first pictures on the right).
I used an addition cured silicone with 22 hardness for the mold making. The mixing ratio is one to one by weight. I covered my mold, starting with the face, so the silicone layer was roughly 1-1,5 cm thick. I then added silicone keys which were made from pre-cured silicone cubes (see reference photo). The edges were then trimmed and I had to make another dividing wall on the middle of the face to get a total of 4 part fiberglass jacket.
Fiberglass jacket is made by first mixing a polyester layer with 2% hardener and Cab-O-Sil filler which is then brushed on the surface of where the mold is going to be. Wait until it is tacky and then add fiberglass chopping on and it is ready to dry. When dry add polyester, 2% hardener and cover the whole surface again and might put more fiberglass chopping mixed with polyester and hardener around the silicone-keys and places the fiberglass-tissue have problems of getting contact. This it to minimize delamination (air-pockets in the fiberglass). Then proceed to mix polyester and hardener to wet the fiberglass tissue and cover the mold, 2 layers of fiberglass tissue and 1 layer of fine tissue (for the beauty coat) to get a clean surface and not sharp and pointy mold in the end. (you'll find a timelaps of this further down.)
When the front of the face was finished, I did the same on the back of the head.
All fiberglass needed to be trimmed with a Dremmel tool, and drill key holes before opening it.
After opening it, then it was time to clean away all clay and the jacket was done.
To make the skin that will be the thickness of the foamlatex, I laid water clay in the thickness I wanted for the foam. Them I made a new fiberglass mold of that. First with the mold open, then I closed the mold and sealed it together.
When this was done I had a core for my mold.
I had to fill all gaps with fiberglass filler to make the core as smooth as possible so the foamlatex wouldn't stuck or rip.
I had to make a master-mold of the core so I can remake it for as a "helmet" for the foam-latex skin. I made a little video of the process of making the master-mold and core. with the same procedure as above, silicone and fiberglass. (see the fiberglass and core video)