Part of the appeal of an old, well-made violin is its beauty; as the violin ages, so does the wood and the clear, protective finish. It darkens over time and, if properly cared for, should remain intact, except where the friction of your fingers and the bow may wear down the finish. If you have a particularly old and valuable violin, it is best to spend the time and money to have it professionally refinished. However, for an inexpensive or practice-level violin, it's reasonable and cost-effective to perform the varnish removal yourself, preparing it for a new layer of wood-preserving finish.
Remove the violin's strings and fill the acoustic cavity with soft, clean rags.
Plug in a hair dryer and turn it to its high setting.
Move the dryer in small circular motions over the surface of the violin, concentrating on one 5-inch inch area. This softens the varnish and makes it easier to remove. Do not hold the heat in a static position over the violin, to avoid burning the surface.
Scrub away the softened varnish using a copper scouring pad. Be gentle so that you do not scar the wood. Continue softening 5-inch areas and scrubbing away softened varnish over entire violin.
Scrape away any stubborn or residual varnish with the razor blade, dragging the blade horizontally over the area.
Do not use chemical varnish removers on any violin. Most commercially available varnish removers are too harsh for a violin's woods.