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Byne’s Disease – Questions and Answers
Paul Callomon (Collections Manager, Department of Malacology, Academy of Natural Sciences - Philadelphia, PA)

1.What is Byne’s disease?

It’s a 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 from?

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 play?

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.

Red herrings: 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?

Apparently not. 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?

Ideally, don’t 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 chain.

The environment 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 others?

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 help?

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.

More detailed 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.

An excellent 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.


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