The small little details take up more than half of the time, but they are what make the skull look authentic. I added several details in the skull, behind it, on the orbits, crests and palate. I used several techniques: creasing, burning, heating, melting with PVC glue, scratching, removing foam, adding foam, adding acrylic resin and staining with coffee. Here are some pictures.
The orbits stand out laterally. By folding and stretching the foam I was able to shape them well but one more layer of foam is needed to make it stand out as it should. This is the orbit before adding details.
Most of the crest details are obtained by heating the foam with a lighter. Not burn. The lighter has to move from the inside to the outside. The first time will barely cause any effect, but the foam will heat a bit. The second time it will shrink, and after that it will produce bubbles which make the effect you can see below. If you go beyond that it may melt or catch fire. If you previously mark anything with a pencil you won’t be able to erase it later. You can draw veins with glue, wax, paint, and when you heat the foam, that part will be protected so you can control which parts will stand out and which parts will sink in the crest.
After the fire I also added thin strips of foam for the crest details around the orbit.
I don’t know what the inside of the head looks like. Most of the time it’s not visible. After some research I did something like this for the Tupuxuara, and I decided to repeat it here.
This is the palate almost done. I’m working on the posterior part of the skull.
Here I added some details around the occipital bones.
Finally, I coat the foam with a layer of flexible and matte acrylic resin. It not only strengthens the foam making it less liable to crack, but it also protects it from corrosive chemicals which could melt the foam and reduces significantly its flammability. The foam becomes harder on the outside, but the resin is somewhat flexible, so it’s easier to rip a piece off than to crack it. I could also add a layer of epoxi resin to make it even more resistent and hard, but I usually prefer not to since that significantly increases the weight, changes the texture and leaves the skull with a shiny surface. I usually only add epoxi to the fragile parts (beak tips, and thin parts that stand out) and to surfaces which will be in contact (the jaw hinges). After the epoxi is dry, I scratch it a bit and add acrylic resin over it.
After the resin is dry, I make a cup of coffee and save the used powder to stain the skeleton. I usually sand the smooth parts before doing that (mandible, orbits, etc.) By adding powder multiple times, and rubbing firmly it with fingers, a toothbrush or lightly with a paintbrush, I can achieve different effects and make some parts darker than the others.
In the next post I will publish the final results.