What happens when you soak charcoal in oil?

Vine or willow charcoal soaked in linseed oil overnight to create a drawing tool with a dark mark that doesn't rub off easily.   But only make what we can use in one day as the charcoal hardens quickly.

Oooooo... Without watching the video, I'm thinking something like a cross between charcoal pencils and black oil pastels... Rich and lovely!!

And, now that I have watched it... I can't help wondering, if it stops working when the oil dries, maybe just having several pieces in the oil, and storing them in the oil would be the solution.