ASK VIOLIN MAKER JAMES MCKEAN, author of Common Sense Instrument Care, about the use of cleaners, polishing, and even having your instrument professionally cleaned and polished, and his advice is straight from the hip: “Avoid it at all costs,” he says. “The best approach is to stop the dirt from building up in the first place.”

Just wipe off rosin and sweat with a very soft, well-laundered cloth when you’re done playing, or more frequently, McKean says. Do it every time and nothing more is required to maintain the finish on your instrument. The virtuous and conscientious can stop here and add a gold star to their practice charts. However, if excessive rosin, sweat, and dirt have built up—due to circumstances beyond your control or because of some misstep—read on.

Like virtually everything to do with stringed instruments, information about cleaning seems to conflict and expert opinions contradict. Some dealers market attractive little bottles of cleaners and polishes to their customers while other shops refuse to include them in their inventory. One expert will advise an annual French polish while another shudders at the practice, since these substances can soften the uppermost layer of the varnish and add a new layer of shellac and oil.

Some of the apparent contradictions have to do with the number of variables involved. For example, a solvent that would leave most violin varnishes unharmed might dissolve the finish on a mass-produced instrument.

“Then there’s the question of how settled-in the varnish is,” pipes in violin maker James Wimmer of Santa Barbara, California. “It gets fairly impervious once it’s hardened into what it’s going to be.”

The next question is just what’s in those attractive little bottles. “You cannot know what’s in a polish, and they don’t label them. It could be anything,” says maker Joe Grubaugh of Petaluma, California. Most contain highly-processed waxes, some with a slight abrasive, he says. Others contain silicone, which goes down into cracks, preventing them from ever being repaired. At best, polishes sit on the surface and absorb dirt. A simple buffing with a clean cloth will produce a subtle shine that no polish can imitate.

“Commercially available cleaners don’t work—if they did they’d be dangerous,” says McKean, who points out that alcohol, the solvent for rosin, is the same as for varnish. Most cleaners are a combination of wax and linseed oil, he says, which will build up and harden over time into a second varnish that obscures the original coat and is very hard to remove. Other possible ingredients include turpentine, acetone, alcohol, talc, and something to make it smell good.

David Bonsey, a violin maker and instrument specialist at Skinner’s auction house in Boston, believes some commercial cleaners can be used safely, if used as directed. His personal formula is still marketed by a former employer. “You have to shake the bottle,” says Bonsey, noting that ingredients can separate and the most astringent may be the first to reach your varnish.

Most of the commercial products sampled by Strings came with no instructions at all. Those that did were minimal, saying nothing, for example, about the dangers of the contents separating or getting the product into cracks.

Surprisingly, one of the most common, and certainly the most readily available, solvents is spit, which is also used in fine-art restoration. Spit will dissolve anything eventually, acknowledges Bonsey, who was not the only expert to suggest it.