Wet/Dry sandpaper

[Mike Stafford]

I know that you are supposed to use water when sanding with silicon carbide sandpaper. When I am sanding bare steel the water seems to create a slurry of grit and metal. I also know that you use water when sanding bare metal and primer in preparation for painting on a car.

My question is why do you use the water? to float away the sanding dust? to float away the metal grit? to lubricate the sandpaper in order to extend its life?

I have also used water while sanding wood and wood finishes. I usually use water or some other lubricant to reduce heat generation on dense wood subject to heat checking.

 

[Vaughn McMillan]

My understanding is that the water floats the sanding dust away and also helps keep the paper from clogging. It's much like adding water or thin oil to a sharpening stone. The net result is a better finished product in less time.

 

[Dave Hoskins]

Sounds logical to me, Vaughn. Though I confess I never thought about. Just did it as it seemed everybody else did. Figgered they knew more about it than I did.

 

[Darren Wright]

It keeps heat down too, which can break down the paper, and keeps paint from melting and building up on the paper if sanding it.