Just the liquid. you'll see it turn black & sometimes get gummy, just keep the drill moving don't sit in one spot.
You may have to go over it more than once depending on the condition. that BMW motor was horrible and took a while.
Hope that helped
Originally Posted by good2bsims
Are you leaving the wadding from the Never Dull on the material when you use the brushes? Or just the liquid that comes from the wadding?