Color Sanding MDF

[krazy]

If I paint my MDF with a black oil-based paint, then try to sand it to make the coat smooth, won't it embed the sanded dust into the coat and/or make the paint look gray from sanding?

I recently painted a MDF coffee table and was afraid to experiment as it *had* to look good but I experimented in a small corner with sanding the paint coat. When I sanded it, it went from black to gray as I sanded paint off. It didn't simply 'flatten out'. Instead, it turned grayish.

Additionally, I tried, in a small corner, sanding my overcoat of Shellac. That caused the Shellac to also appear dusty and I imagined that it would make the finish cloudy instead of clear (from the abrasive surface over the clear).

What was I doing wrong? And how can I get something like this with MDF:

Thanks!

 

[Jasonb]

The "grey" is caused by fine scratches left in the surface.

You can either work through sucsesively finer grits down to 4000-6000 used wet.

Or after sanding the colour to 1000g clear coat, If your clear coat is not as you want then it needs power buffing.

This is one reason why an automotive paint is better than oil based as it dries harder and is easier to sand/buff.

Jason