I want to be sure to tap Sara's expertise with regard to a couple of conservation issues we all face with regard to the rugs and textiles that we own.

Although a number of collectors and dealers I know deny ever having had moth in their material, I have actually seen moths flying in nearly every rug store that I know here in DC. So I assume that folks still worry about moth protection.

Here's my question, Sara: Are there any problems in using moth balls or other
insect repellents directly on rugs? A great many of us still do it. And what do you recommend?

Regards,

R. John Howe

Mothballs (paradichlorobenzene) is a liver toxin (human) and a known carcinogen (in rats, but who wants to take a chance). It can cause breathing and allergy problems (lung and contact). AND, it softens plastics and paints, damages some dyes, and can leave an oily residue that is hard to remove (these residues are not a part of the pesticide, but are used in manufacture to hold the crystalline material together).

Formulations for sprays change frequently and are often proprietary, so it's hard to keep up with them. In museums, we certainly don't use them because we don't have enough information on their long-term effects.

What we do use is freezing. I won't go into the details of "how to" here because the information is available on The Textile Museum website along with another of other textile care brochures (they can now be downloaded from the site). There has been a serious amount of research done on freezing, and even at super cold temperatures, there is no damage on the fiber level after hundreds of repeat freezings. Moths and carpet beetles are killed (all life stages) at -4 degrees F., much "warmer" than the damage studies that have been done, so it can be done without fear. A note: you have to use a freezer that does not go through a defrost cycle (i.e., a frost-free freezer won't work), and you must be able to maintain the temperature at the minus 4 degree level over a period of 48 hours. In general, a domestic chest freezer will do this easily.

Most of you can likely find readily the Textile Museum site and the section of it that gives "care" advice.

But just to make sure, here is the link:

http://www.textilemuseum.org/care.htm

I think it will be a live one but if not, copy and paste into the "address" line of your browser and press "Enter."

Regards,

R. John Howe

I'm sure the freezer treatment for moth prevention works nearly perfectly; it is also the preferred method for getting rid of insect infestations in African art (usually wood). On the other hand, I think the people who did the research didn't do a very good job of explaining how it works, or didn't understand it themselves. Let me help out in that.

Freezing kills insect eggs by the formation of ice crystals, which disrupt cell structure. For the same reason, freezing will do some damage to any textile that is not completely free of water (and, trust me, none of the textiles we're talking about are absolutely anhydrous). That damage will be trivial, of course, especially if not done more than a few hundred or a few thousand times (like brief exposure to high intensity light ).

The fact that the research used temperatures much lower than the -4 that the TM uses does not make the TM procedure safer, it makes it more dangerous (but still trivially so, I emphasize). The reason is that ice crystals form most readily when the temperature of the water falls slowly. If you plunge water into a supercold environment so that it falls to very low temperatures very quickly, there is much less crystallization.

The reason for needing a couple of days in the freezer to do the job, by the way, is not that ice crystals do their work slowly, but that it takes awhile for the temperature drop to happen deep inside a textile (or piece of wood). Wood and most textile materials are pretty good insulators, and the cold doesn't kill until it reaches freezing temperatures.

Regards, and many thanks for your contributions to the dialogs,

Steve Price

Which reminds me of the story about the parrot that only talked in profanities. The owner didn't mind so much, but his wife was shocked and demanded he do something. The man tried everything: bribes of macadamia nuts, scolding, leaving the hood over the cage for days on end. But nothing worked. The parrot kept right on swearing a blue streak. At his wits end, the man put the parrot in his freezer for two minutes. When he removed the bird, it spoke without a single oath. "Thank you, kind sir, for removing me from the freezer. I hope we will have a long and rewarding life together. And, if I may ask, what did the chicken do?"

-Jerry-