Thanks so much for posting this article. I will keep it
for my files. It is very interesting and I do have linenbacked posters in my own
collection that were fine when I bought them, but over the years there are small
patches that have begun to discolor. I wondered what that was since the
environment they are in is fine. I may have Sylvia have a look and perhaps
consider relinenbacking and cleaning of those areas. Thanks again for the superb
article.
----- Original Message -----
Sent: Thursday, September 15, 2005 8:48
AM
Subject: [MOPO] Foxing
here's some good reading,
Foxing can
be masked with laundry bleach which might look okay the first couple years,
but Chlorox does immediate damage to the cellulose content of paper, & the
residue salts cause increasing damage in the long run. There are additional
chemical means of neutralizing the residue salts, but those additional
chemicals also have long-term effects.
Foxing can
also be masked temporarily with peroxide, but peroxide damages paper even more
quickly than Chlorox. Both methods are essentially those of the ignorant or
the crooked.
Unfortunately foxing is most frequently caused by a living organism
which may or may not continue to grow. In ideal conditions of temperature
& humidity for the book, this fungus either ceases to grow or develops at
a such a low rate that the chemical solution residues are the more harmful in
that chemical residues will hasten rather than retard the natural break-down
of paper but the arrested fungus may remain only a minor speckling of
discoloration.
Some tests
on foxing detect no fungus present, so some archivists posit the possibility
of multiple causes, leaving an element of "mystery" about the cause &
nature of foxing. One thing is fairly standard: foxing occurs best in papers
that contain iron impurities or high acidity. Iron is usually introduced into
paper during manufacture, from water containing iron, from old papers
manufactured with aid of iron machinery & iron beaters. Foxing caused
exclusively by iron, & not by fungus, archivists distinguish as "dendritic
growth stain" & at its ugliest it is a big fan-shaped discoloration that
apparently follows some metalic molecular pattern. Fungal foxing usually
requires paper acidity, acidity being the result of bonding agents used from
the 1890s through 1980s on cheaper papers, though it's possible the acidity of
some foxed books is a byproduct of the fungus itself. Both forms of foxing are
treated the same way, by washing the paper in an oxidizing agents, which
requires submersal in dilute chemical then rinsing.
Talus, a
company in New York, sells powdered Chloramine-T specifically for use in
removing foxing from archival materials, including books. Unfortunately it
requires the powder to be dissolved in water & the foxed item to be
immersed in the water, then submersed a second time to rinse out the Chlor-T
residues. So it treats one signature-leaf at a time, the book having first to
be disbound.
State of the
art archival preservationists have found that even the Chloramine-T leaves a
residue after rinsing, & is harmful over time, but no better option has
been proposed. It is restricted to use on items truly worthy of preservation,
& which have egregious foxing. All de-foxing chemical bleaches have to be
rinsed. A book of considerable age & rarity that is being devoured by
fungus, it can be disbound, each separated signature soaked in dilute
Chloramine-T, then rinsed to remove residues, & rebound. This is not very
useful for entire books of only average value.
There is a
very dangerous & impossible to do at home method of removing foxing from
books that used Chloramine gas. I've seen reports that this is safe for the
book & may be the only method guaranteed not to replace foxing with
waterdamage. But the technique requires resources only the aerospace industry
could provide. The book has to be placed in a riffled-open position so all the
pages can be gassed, & the gas chamber better be air tight. I've never
known of this being done by booksellers, & no standard archival resource
mentions it as a viable option, though the Univeristy of Washington
experimented with it to good results with the assistance of Boeing Aerospace
back in the late 1970s -- I've heard nothing about it since.
Some
archivists claim (hope rather) calcium hypochlorite leaves less residue even
than Chloramine-T soaks, but others have said calcium hypochlorite clings so
well to paper it is extremely hard to rinse out & so is not preferable to
Chlor-T. Again, it's a submersal technique, hardly practical for books.
One old
method is a three-part deal, requiring three photographic chemical trays. The
first tray has potassium permaganate diluted one to 16 parts water. Each page
is submersed for a half-minute this solution, then moved to a second tray with
sodium meta-bisulphite diluted one to sixteen parts water, again for a
half-minute. The third tray should be a "flushing" tray with water running
thrugh it continuously. This a rinse, to wash out the killed & loosened
foxing, & to remove the chemicals themselves. This elaborate method has
pretty much been displaced by Chloramine-T or by calcium hyupchlorite which
requires only one rather than two distinct baths before rinse.
Sodium
borohydride in a 5% solution is also used. The majority of archivists don't
seem to use it, but a few claim it does not need to be rinsed, because its
residues leave a deposit of alkalinity that might actually benefit the paper.
Exposure one
sheet at a time to UV light (artificially generated, or mere sunlight
exposure) is the only "safe" bleaching method & even that is not safe for
paper containing lignen, which will rapidly oxidize from ultra violet
exposure, with darkening effect as lousy as the foxing. It works best with
slight moistening of the surface & strong UV radiation. If it's just the
random page it might be a tolerable method, otherwise it takes one hell of a
long time. The moisture-&-UV method is reportedly the least damaging of
all methods (except possibly the unavailable gas-chamber method). The Paper
Conservator #21, 1997, has a lengthy article on the method: "Aqueous light
bleaching of modern rag paper: an effective tool for stain removal." It is
useful for cleaning foxed color plates that have been removed, treated, &
reinserted, but doing it to an entire book would not be time effective.
All methods
requiring water (dampening, or submersive) risk damage towater soluable inks.
Most dyes used in books are color-fast but very old books with color plates
sometimes used indigo in the inking mix to achieve purple & blue
colorations that will bleed when dampened. Further, rinsing with fresh water
(from the tap) risks introducing iron impurities to the paper, damaging over
time, so dionized or distilled water is sometimes recommended. High quality
papers can sometimes be wetted in a manner that will dry unharmed, but an
awful lot of papers will either change their thickness or wrinkle before they
dry, & that damage is irreversible. Spot-testing helps in the decision
process. By & large it is a trade-off & defoxing is recommended only
when the level of foxing is more detrimental.
But I'm
afraid any bookseller who claims to have a magic method of foxing removal is
likely spraying a mist of dilute Chlorox that damages the cellulose in the
paper & does permanent harm, though if he can sell the cleaned-up book
quickly enough by making it look momentarily nice & bright, he's probably
succeeded at his only real goal. All functional methods apart from UV exposure
require submersal so one would expect signs of a book having been disbound
& rebound, with some slight evidence of contact with water if not outright
overt water damage.
The bottom
line is there is no truly reasonable & effective way of defoxing a book,
perhaps at most these methods are credible for a single fox-stained
illustration plate or a few gregiously fungally-darkened pages that'll look
better slightly wrinkled than they look all splotchy.
Books stored
in temperature controlled rooms (in the 60-67 degrees F range) with no more
than 50% humidity will not develop foxing, & foxing that is established
will be retarded in further growth. If you live in the Philipines or South
Carolina or Dallas where humidity can be 100% then books that have foxing
started in them are pretty much doomed & will infect nearby books as well,
unless a first-rate dehumidifier is in place.
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