The Dos and Don'ts of Painting Varnished Furniture

DON’T attempt to paint over varnish 

The clear protective coating that shields furniture from scratches and scuffs is so slick that it almost repels paint. A telltale sign you’ve painted over varnish: The paint bubbles and peels.

DO try to remove the varnish...

With sandpaper first. Start with coarse 150-grit sandpaper, followed by a finer 220-grit sandpaper. For varnish that refuses to budge or lingers in crevices, apply a paint-and-varnish stripper like Citristrip, then sand with a fine-grit paper.