Pour some chemical stripper onto the varnish. The best varieties for varnish removal are the thick gel types.
Brush the stripper around cover all areas with a thick coat, using a paintbrush. Allow the stripper to work and soften up the varnish. This action will usually take about 15 minutes, but different products have different times, so follow the label instructions.
Scrape the stripper away with a putty knife for long, flat surfaces and steel wool for curves, dips and angles. As you remove the stripper, the varnish will soften and liquefy, and will be removed.
Attach 40- to 60-grit sandpaper to a sanding block. If using a power sander, attach a sandpaper belt or sheet of the required grit to the sander.
Sand over the surface and remove the varnish. Check your sandpaper regularly as the varnish has a tendency to "gum up" the sandpaper. When this happens, a new sheet or belt must replace the old belt or sheet to maintain sanding efficiency.
Loop the sandpaper around your fingers, a pencil or any other object that will allow you to get into tight or compromising places and sand curves and angles manually.