Francis A. Miniter wrote:

The researchers note that the use of Thymol does result in the
degradation of the paper support, though they do not know the particular
process. They recommend against its use. As an alternative, they
recommend exposure to sunlight, as I had noted.

Thanks for the info, and the reference -- the Thymol process was described
in one of Arthur Johnson's books on book restoration, and it stuck in my mind,
mainly because it Thymol was (and probably still is) an ingredient I could
actually buy over the counter.

I would like to have seen some further experiments to rule out any effects
the PVC and polypropylene might have had, even with the only slight heating
present. And there are a bit too many 'appears to' -- one of the most important
are in the abstract which says only that 'thymol appeared to have a deleterious
effect on the paper support, on gum arabic, and on iron gall ink', which
is a rather weaker statement that that it actually had such effect.

Sunlight is an antibiotic -- ultraviolet light has that effect. It also
breaks down cellulose bonds, and so increases paper degradation. Thus, I can
hardly believe that either the author of the paper or you recommend it
without precaution. Through a piece of glass much of the UV light is removed,
and so again the question of actual mechanism is raised: is it the exposure to
sunlight that does the job, or simply that the book is aired and dried out, causing
mold to deactivate, and that a night-time operation with gentle heat applied would
have the same effect?

I think I asked this once, several years ago, but I don't remember an answer.
Perhaps you know?

--
Anders Thulin anders*thulin.name http://www.anders.thulin.name/