I use the towels because they trap dust particles. Even though I pull my car into the garage when I dry it, dust is in the air and sometimes lands on the car. Since the towel has a nap, it traps whatever dust there is in the towel. I use two or three towels to reduce the chance the dust particles will work their way out of the nap and scratch the car. The water blade I used dragged a particle across my trunk since it couldn't absorb it. I used to work at a marble and granite countertop place so I took my water blade there (all the polishing pretty much is wet polishing). I managed to scratch a black marble table top with the water blade. Granted black marble is a rather soft stone, but it's still harder than my car's paint.
That's just my 2 cents.

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1984 300TD Turbo 156Kmi
"He who seeks knowledge begins with humbleness" - Buju Banton