|Flexible detail coat added to burlap mask|
It turns out that the natural polymer starch I have been working with (tutorial here) can be used a bit like acrylic artist's medium.
It is a great flexible binder for mixing with loose, fibrous material like Celluclay, which is made from recycled newsprint, dried and powdered.
The polymer starch and Celluclay mixture sticks to the burlap really well, and gives this branchy hobgoblin a nice barky texture.
Because flexible surfaces need flexible paint, I decided to use gelatin as a binder (basically hide glue) combined with several clay and mineral pigments. An added side benefit of this type of natural paint is increased moisture-resistance, as hide glue has waterproofing properties.
The finished piece! The pigment colors ended up lighter-toned than I had planned for, but I decided to keep them since I like the bone-like effect.