Ok, I know why. To help the new paint stick better.

Two questions.

1. What is the difference between wet sand and dry sand? Let's say painting a bumper.

2. I know, sandpaper. Why not fine steel wool? I know it sounds ridculus, that's not what I'm trying to use. I just want to understand the process.

 

You want to wet sand because dry sanding cause's paper build up which cause's unwanted deep scratches and you won't ever get the panel smooth, it also helps the paper last longer hope that helps to a point.....

 

Oh also... Steel wool won't sand it will just scuff..

 

Now I know.

Thanks.

 

i dont really think steel wool is good for sanding a paint surface for respray... theyre not really made to sand/scuff like sandpaper or scotchbrite does... if u wanna use something then use scotchbrite. Grey color.

 

Wet sanding prevents material build-up on the paper and surface. This lengthens the paper's life and prevents dust from altering the scratch pattern, producing a better, more even surface. It also allows you to better see the surface you are working on. Dry sanding works faster and is used until pre-paint sanding, where the sand scratches can affect the look of the finished surface.