Prepping Poly for Paint

Tips on how to scuff-sand poly before repainting. February 13, 2009

Question
I have a customer with a pool table and front door that are finished in a poly top coat. I need to refinish them in black. Because of the location, size, and intricate details it is a bit impractical and awkward to strip them so I am considering painting them black over the poly. The question is can I achieve good adhesion and what would be the recommended process and products to use?

Forum Responses
(Finishing Forum)
From contributor C:
Sand with a coarse (60 grit) sanding sponge (3M sandblaster) - just scuff, don't sand hard. Don't freak out at the grit size, the sanding sponges give a lot finer cut than paper of the same grit and used with a gentle pressure this step will be amazingly easy and quick. You could use the 80 or 100 grit sizes but you'd have to work harder to get the job done. After sanding dust thoroughly prime and paint.

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From contributor B:
Just wondering how the 60 grit worked out? It sounds a little rough to me.

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From contributor C:
It's a huge time saver. There have been numerous discussions of grit sizes and apparently the sponges use a different scale than paper besides which the soft backing also makes a given grit perform as though it were smaller. Used with a light hand the 60 grit "Sandblast" sponges are just right for scuffing previously finished cabinets and furniture. I speak from years of experience on hundreds of projects. You can believe it or work your butt off with finer grits. Some people like sanding! I switch to 180 grit (still "Sandblast" sponges) for denibbing between coats.