This is the flattening procedure, where you spray on a carbon dust and then use a wet, foam squeegee to uncover the high and low spots that you won't see otherwise until your paint is dry.
Here we are next door in the paint booth, cleaning, masking, and masking some more. It is in the early stages of masking, as you can still see the hubs as well as under the car. When we were done it was paper city.