Disease – Questions and Answers
Paul Callomon (Collections
Manager, Department of Malacology, Academy of Natural Sciences
- Philadelphia, PA)
1.What is Byne’s disease?
name used to describe damage inflicted on shells by acid vapors.
It honors Loftus St. George Byne, who published the first paper
on the subject in 1899. Most of his conclusions were wrong –
he thought the problem was caused by bacteria - and the treatments
he prescribed were either useless or actually dangerous, but
the name stuck.
2. Where do the vapors come
They are emitted
naturally by wood and other cellulose-based materials such as
cotton, paper, cardboard, chipboard, plywood, Masonite, sawdust
and cork. They are a product of the natural decay of cellulose.
3. What happens?
The main aggressors
are acetic and formic acid, both of which are volatile –
that is, they actively float out into the air as vapor at room
temperature. The vapor attacks the calcium carbonate of the
shells, turning it into a calcium acetate/formate compound salt.
The specimen becomes scarred, and is eventually destroyed. The
higher the humidity and temperature, the faster the reaction.
4. What role does humidity
The acid fumes
readily dissolve in water, turning ordinary water vapor into
acidic vapor. One problem is that the salts that form on the
surface of an afflicted shell are themselves hygroscopic –
they attract water. In sucking in water vapor from the surrounding
air, therefore, they also draw more acid into the reaction than
would normally arrive in a drier environment.
5. How can I tell whether
my shells have Byne’s disease?
After a while,
a white powder or clumps of white crystals will become visible
on the shell surface. Favorite spots are in the sutures of gastropods
and among the ribs and grooves on bivalves. You may have to
look hard or use a lens to see anything at first, but in bad
cases the whole specimen can eventually become covered with
white fur. Touch the crystals with the tip of your tongue. If
there is a strong taste of vinegar (acetic acid), this normally
indicates Byne’s disease. A sour smell when you first
open a drawer is another telltale.
some specimens have a white film on them naturally, especially
if they came from sand or mud bottoms, and some glossy shells
‘film over’ for other reasons. Coralline algae can
also form small white patches that may look like Byne’s
disease. In all cases, however, the taste test is very reliable.
6. Are some species especially
prone to Byne’s disease?
I have seen Byne’s disease in marine, freshwater and land
shells. Cones, cowries and volutes all get it, as do smaller
groups such as Triphorids and Turrids. I’ve seen it in
most bivalve groups too. Small, highly-sculptured gastropods
seem to get it quite often, and this may be due to the presence
of sea salt residues on and inside the shell. Ordinary salt
is hygroscopic, which means that it attracts and absorbs water
vapor from the air. Within a wooden case, this vapor may already
have been turned sufficiently acid by the fumes to set off Byne’s
disease. Though this theory is not yet proven, it is best to
thoroughly soak, wash and dry all marine specimens before putting
them in your collection.
7. How can I treat specimens
that have the disease?
Soak them in
fresh water for 24 to 48 hours to break up the crystals, then
wash them in running water with a toothbrush and dry them thoroughly.
This will stop the reaction and remove the salts from the surface.
You cannot restore the corroded areas, but as long as you don’t
put the shell back into the same environment then things should
not get worse.
8. How can I prevent specimens
getting Byne’s disease?
store them in wooden drawers or cardboard boxes. If you must,
then isolate them from the vapors by putting them in glass vials
with plastic stoppers, or in ziploc bags. Open all the drawers
regularly to release the fumes. Use a dehumidifier in the room
and silica-gel desiccant in each drawer to try and reduce humidity.
You can monitor temperature and humidity with simple instruments
available from the greenhouse department of any big home store
within the average shell collection is a balance of several
factors. On the one hand, wood gives off acid fumes; on the
other, however, it absorbs water. Humidity within a well-sealed
wooden cabinet is thus usually lower than in the surrounding
room. On balance, it’s better to store your shells in
metal, glass or plastic than in wood, but if you live in a very
humid climate bear in mind that these materials will offer no
protection from other humidity-associated problems such as mold.
If your collection is big enough to warrant it, you may have
to look at dehumidifying the entire room.
Though I don’t
advise it for any specimen that may one day be offered to a
museum collection, oiling specimens is known to reduce the likelihood
of Byne’s disease.
9. Are some woods worse than
Oak is apparently
the worst wood for causing Byne’s disease. This is not
surprising, as oak is corrosive enough to destroy iron and steel
screws. All woods can cause Byne’s disease, however, and
plywood, fiberboard and Masonite are just as bad. The age of
the wood doesn’t seem to matter much, and it can continue
to give off fumes for decades. Ordinary paper usually gives
off acid too – some of it from the wood pulp, and more
from the sulfides used to bleach the paper. Testing pens are
available at art supply stores that will tell you whether paper
or card is acidic or not. If you can, enclose your acidic labels
in Mylar envelopes or small ziploc bags. Laminating them (like
ID cards) is probably not a good idea, as the long-term stability
of laminated paper is in some doubt, and separating them from
the specimens risks chaos.
10.Does painting the wood
It should, though
unless the paint forms an unbroken barrier then some vapors
are still going to get out. As the seasons change, wood stretches
and shrinks. New paint can keep pace with this movement for
a time, but sooner or later cracks will appear as the paint
loses its aromatic elements and hardens. Still, it’s probably
better to have some paint cover than to have plain wood exposed.
People have tried using flexible latex paint, with some success,
but in any case if your drawers don’t have separate metal
runners then the paint will wear off wherever the drawer slides
against the cabinet. Paint will make the drawer slides stick,
too. Obviously, so-called microporous paints and varnishes are
of no use, as they allow vapors to pass freely through them.
information on Byne’s disease has been published. Sally
Shelton’s excellent roundup of research and publications
on the topic was reprinted in the for August 1999. The IHSN
can be viewed online at Internet
Hawaiian Shell News.
technical paper on the chemistry of Byne’s disease is
‘The deterioration of Mollusca collections: identification
of efflorescence’ by Norman Tennent and Thomas Baird.
Studies in Conservation vol. 30 (2), 1985: 73-85. This contains
some great color plates of really horrible cases. Back issues
of this publication can be ordered from the at International
Institute for Conservation.