What is the way to color tiny parts of a picture with oil pastels? The following video shows that it is possible to color tiny parts of a drawing with oil pastels, without layering and then scraping the top layer:
https://www.youtube.com/watch?v=PuQ4xkb6Q88

I wish to know how is that done? Oil pastels by default do not have sharp edge. They are thick and round.

Are we expected to sharpen them like a pencil? I guess that would waste a lot of color.
Or is there a way to sharpen the oil pastels without much wastage?

What is the way to color tiny parts of a picture with oil pastels?
One method is to use a small piece of the pastel and some solvent to create an 'oil paint' and with a brush complete the high detail components.


  Oil pastel pigment can be manipulated with a brush moistened in white spirit, turpentine, linseed oil, or another type of vegetable oil or solvent. Alternatively, the drawing surface can be oiled before drawing or the pastel itself can be dipped in oil.wiki


I personally haven't used this method, but I watched my Great Auntie finish some of her pastel work with a brush and solvent. Here is a good explanation of how to use solvents and oil pastels: Robert Sloan - Thinner Wash