Strad readers submit their problems and queries about string playing, teaching or making to a panel of experts

instrument clean

In the sixth of the series, three instrument makers and restorers respond to a reader's query about how to keep her instrument clean of rosin.

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The dilemma I always wipe the rosin dust off my cello with a duster, but over time I still find that there’s a sticky build-up on the varnish. Is there a safe way to clean this off myself? What else should I do to keep my instrument in good condition?


ANETTE FAJARDO Varnishes and finishes are made up of various components and react differently to touch and to cleaning agents. Commercially available cleaners can contain solvents that might soften the varnish of an instrument and take off more than you bargained for. They also usually contain an oily or waxy medium. Get that in an open crack, loose purfling line or seam, and they will be difficult to glue again without needing a more involved repair.

Wash your hands before playing and give your cello a gentle wipe with a soft cloth where rosin or sweat have settled down. And yes, have it seen regularly by a luthier you trust for a clean and check-up.

To protect your instrument, never touch the varnish. Just hold it at the neck and end-button or endpin. Also, make sure your instrument is stored in a high-quality, well-fitting case. This is especially important for cellos and violas as they vary in size. Keep an eye on humidity – in hot and humid conditions seams and cracks can come apart, whereas dry conditions can lead to shrinkage cracks.

When the top of the bridge is clean and the string grooves are well lubricated with graphite, it’s easier to keep the bridge straight, which extends its life and prevents it from tumbling over. Ask your luthier to show you how to do this safely.

ANDREW DIPPER The answer is dependent on the type of varnish that the instrument has and whether the wood surface has cracks or varnish retouch present. Most varnishes on instruments are extremely fragile, especially Italian ones from the 17th and 18th centuries, and these should always be cleaned by a very experienced professional restorer.

The problem in cleaning arises because the rosin particles have an active chemical ability to dissolve and combine with varnish layers in a remarkable way over months and years. The particles also have an affinity with dust, oils and airborne acids, which act as a further catalyst to ongoing reactions at the interface of the varnish with these contaminants. Pure shellac varnishes of the type sometimes seen on 19th-century French instruments seem to be the least sensitive to these reactions and can usually be wiped clean without any problem after any extended period of playing. However, if the rosin dust is left on the surface of the varnish for further extended periods of time it may prove extremely difficult to remove.

Proprietary cleaners are commercially available but some of these contain hidden ingredients that can be hazardous either to the player or to the instrument, particularly if there are repaired cracks or varnish retouch in the areas to be cleaned.

ANDREAS HUDELMAYER It is very important to wipe the rosin off as soon as possible – you might try a micro-fibre cloth for this. But depending on the varnish, the temperature and the length of time the rosin stays on, some rosin might still bond to the surface. In all cleaning, the challenge is to remove what you don’t want and to leave everything else. There are various soaps and cleaners around but none of them can be used without a lot of care and knowledge.

One thing I can recommend is a polish that has a mild abrasive in it: Super Nikco. Unfortunately it’s not widely available. You should polish it on with a soft cloth in a circular motion, then polish off the slightly milky layer with another soft cloth. Use a white cloth, so that you can see exactly what colour comes off. You’ll want to see the green– brown colour of general dirt, not a varnish-like orange.

If you are not careful you run the risk of damaging the instrument, but all in all, this method should be fairly safe. But for anything that you cannot remove easily, I recommend you go to a violin maker and have your cello professionally cleaned.

Anette Fajardo is a London-based violin maker who works as a restorer at the Royal College of Music

Andrew Dipper is an instrument maker and restorer, historian and writer based in Minneapolis, US

Andreas Hudelmayer focuses on new making and tonal adjustment in his central London workshop

Do you have a burning question about string playing, teaching or making that you need answering by people who really know? Email us at