After sanding down the filler whats a good thing to wipe down the bumper with before laying down a layer of primer to see high and low spots?

 

I usually go a bit of rubbing achohol and water in a spray bottle then just wipe dry. Following that I apply a good thick coat of high build sandable primer that really brings out the uneven places. Then back to sanding lol.

 

Thanks. I bought some sandable primer and its been working out great. Rep given!