Exactly! My old letters prove lunaf16's point, some ink just vanishes.

Actually, the clay itself can be a real problem during long shoots. In my experience, it gets soft under hot lights and picks up every bit of dust. That 12 fps rate helps, but you still have to move quick before the figure loses its shape. Consistent lighting is key too, since even a tiny change can make the frames look jumpy. Planning each shot with rough sketches first saves a lot of headache later.