Friday, December 17, 2010

Just Mothball It

From the desk of Colleen Wilson,
Conservator at the Royal BC Museum

Getting your woollens and furs out of mothballs? Phew, what a stink! It’s nice to have our warm wraps ready to go, but is there a quick way to get rid of the smell?

Short answer: no. The long answer is a question about the wisdom of protecting our treasures with dangerous chemicals.

Some years ago a rare military uniform was donated to the Museum. Unfortunately it had been stored in mothballs and when the container was opened, staff had to leave the area because the naphthalene fumes were overpowering. Although the curator was anxious to acquire the uniform, it was obvious that it couldn’t be catalogued, stored, or exhibited.

The jacket in the tray of cat litter with a filled bolster.

Following an “old conservators” remedy for reducing the mouldy smell of old books, the uniform was “buried” in absorbent material. Two large plastic storage boxes were half filled with standard (unscented) cat litter; tissue was placed on top of the litter to permit fumes, but not dust, to pass through. The jacket, with cotton bolsters filled with litter inside the sleeves and body, was placed atop the litter in one box, the trousers in the other and the boxes were sealed.

The uniform ready for cataloguing
by Delphine Castles, Collections Manager.

One year later the smell was substantially reduced, but it was not gone. So the cat litter was replaced and the uniforms sealed up again. Eventually the fumes were eliminated and the uniform joined the History Collection. It only took two years.

Despite the difficulty in getting rid of their smell, mothballs are not an effective way to protect against insect damage. To actually kill the moths that damage furs and woollens, a high concentration of naphthalene is required: one pound of mothballs to 10 cubic feet. And, an entire life-cycle must be fumigated, the container sealed for a full month. Tossing a handful of mothballs into a closet or storage chest will only give a false sense of security and expose you to harmful fumes. Fumes that will kill an insect are not going to do you any good: inhaling naphthalene is hard on the liver and kidneys and with overexposure, many people become sensitized. And there is the persistent smell.

Case-making clothes moths caught on a sticky trap.

Many consider cold storage a better option for furs, but the real benefit of cold storage is in the thorough preparation and the sealed facility. Cool temperatures alone will not preserve fur.

Freezing, however, is an effective way to kill insects. Although they can overwinter in cold climates, this is because the gradual lowering of the temperature allows insects to enter a state of “diapause”; keeping an infested artifact warm before plunging it into a -18C freezer will result in death to all stages of insect life. (An unburdened chest freezer should be able to do this; a domestic upright freezer is not cold enough.) Freeze the artifact for 48 hours. If it was sealed in a plastic bag and left there until thoroughly thawed, the artifact will retain its original moisture content. In fact if it is intended for storage, it can remain in the bag until needed – it is free of infestation and isolated from new insects.

Although there are many “old wives” remedies for repelling insects with herbs, wood chips even champagne corks, in reality it was the old wives’ good housekeeping that did the trick: if winter clothes are put away clean in a sealed container, insects cannot get at them. No need for mothballs at all.

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