Yeah cool, exactly, got to try those electric erasers with the subtraction technique.
Here is something really old, kind of the subtract technique but you draw the highlights instead and use the black paper as the shadows, anyways tried to...

I know allot of stuff in wrong with this, proportions and all, it was also my first with this technique and I think I did not have a reference, can't remember, maybe for the eyes...

Some portrait master told me to try this and I do believe everybody would benefit in trying this cause what you trying to do is to see the highlights and nothing else, kind of like sculpting, it is a kind of subtract technique I think.