Optics and Mothballs

The outdoor shed where I keep my telescopes has often been burrowed under by woodchucks. A local manufacturer of portable buildings recently suggested that I sprinkle mothballs under the building to keep the critters away. Apparently, they don't like the smell. Even if that works, I'm concerned about the effect the fumes might have on my optics. Does anyone know if mothballs would damage the coatings on telescope mirrors and lenses?
Thanks, Steve.

I don't believe any damage in the form of chemical etching/reaction will occur on the optics or their coatings. The chemical used in mothballs is either Naphthalene or Paradichlorobenzene. These chemicals produce the odor through slow sublimation (conversion from solid to gas phase without forming a liquid during the change). They are relatively chemically inert so I don't see attack on optics as a problem. I believe all reflective and anti-reflective coatings are purely inorganic; mothball chemistry will not react with them.

There is a chance that a thin chemical deposit can form on the telescope via condensation. You should be able to tell if this happens by odor; does the scope smell like mothballs after being removed from the shed several hours later. I don't know if you will be able to visually detect any deposition. There is a chance that the mothball chemicals can affect some paints and plastics; maybe soften or dull a finish. Wood will definitely absorb the odor and may take a while to sublime back off. A shiny wood finish might dull from exposure.

I guess the best advise is "Maybe it's best to store the telescope away from mothballs to avoid the other potential problems".

Dave Keller