[NHCOLL-L:279] Shell Collection -Reply

[Sally Shelton]

Dear Karin,

Stop the treatment you are using. It is very damaging to the shells. The problem with amateur shell groups is that they are extremely well-meaning but their literature is not peer-reviewed, leading to untested treatments like this. The bleach dates back to a time when it was assumed that Byne's "disease" was bacterial in origin (I have gone into this in detail in a paper published in _Festivus_). It is *not* bacterial (you can swab any surface and culture out bacteria, but opportunistic presence at a site does not mean that the bacteria are implicated in the problems). Treatments based on bleach, corrosive sublimate (=mercuric chloride), alcohol, etc. are completely ineffective.

Byne's "disease" is a mechanical process of calcium salt formation and efflorescence which physically ruptures the shell surface. It is a reaction to high or fluctuating relative humidity levels in storage and may be hastened by storage in an acidic environment (wood [especially oak], non-archival cardboards and papers, raw cotton, etc.). We see it much more often in marine shells, causing some people to suspect that ambient salts from ocean water may also be part of the initiating reaction. You can physically scrape or soak the salts off, but that does not resolve the underlying problem; they will keep forming, especially if the shell has been soaked and dried before being returned to the same environment. The best control is lowered RH, either in the macroenvironment or in (nonacidic) microenvironmental enclosures. Coating with any oil or wax is also not recommended; it may slow the reaction but it makes the shell surface a particulate pollution trap and sets up problems down the road, as well as compromising any value for future biochemical work. 

Byne published a series of increasingly shrill papers at the turn of the century, claiming that he had determined that the problem was bacterial by the acetic-acid smell of the shells (with no testing or other proof, and a strikingly poor grasp of bacteriology). He refused to consider any other mechanism and never tested his hypothesis. Unfortunately, this half-baked approach has made it into the popular mentality in the shell collectors' world, and millions of shells have been subjected to damaging treatments that have no real effect on the problem (and probably dozens or hundreds of museum workers have carried out treatments that were very hazardous to their health). Even though the bacterial theory was soundly debunked in the 50s and 60s, a leading malacologist stated in a major publication as late as 1985 that the problem was bacterial, strictly from hearsay. Oral history can't be substituted for sound science.

Best approach: Keep the shells dry, brush off the reaction product (any aqueous solution risks severe damage to the shell), and construct protective microenvironments that are both low-RH and non-acidic if you cannot change the storage macroenvironment (and few of us can). The method described in SPNHC Leaflet 1 for constructing anoxic enclosures will also work well for constructing these; just leave out the oxygen scavenger. Or use museum-grade plastic boxes. Use the bleach elsewhere. 

Cheers,
Sally Shelton
Collections Officer, NMNH
Smithsonian Institution


>>> "Karin Scott" <scott at TM.UP.AC.ZA> Tuesday, 12 October 1999 >>>
Hi

I took the museum's shell collection under my wing not so long ago and I was wondering if you all might have some advise.
  
First a little background might help: The collection stems from the late 1800's up to the 1940's about.  The researcher left the museum and due to a lack of funding and being inland the department was closed and the collection packed and stored.  Part of the collection was exhanged for bird eggs with another museum (1970's) and most of the data except for what is left on the cards with the specimen are gone.
 
Scientifically speaking the collection is not that valuable anymore but it can and is still used for, comparison purposes.  It is a huge collection comprising of national and international shells.  Seeing that we no longer have a shell department and is located inland the collection will remain a static one.  

I had the shell club of Pretoria come and sort through the collection and put them in family catagories.  I was told that my shells have "Baynes(sp?) disease" and that I should do the following to clean and then protect the shells.

I should put the shells in a 50% Household bleach 50 % water solution for at least a day (24 hours) and then in clean water for another day (24 Hours) Let them dry and then rub mineral oil on the shell (Do not submerge the shel in oil).

I have been doning this and have now finished about 4 of the smaller families ± 2000 shells.  (not even 1/4 of my collection).  

I would like to enquire if there is something else I should do or if you think this is sufficient.

Please keep in mind that money is an option (as it is everywhere else) and that there is no way that I can do anything to keep the correct temperature and humidity in the shell collection.

Thanks for the help

Karin

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Miss Karin Scott
Collections Manager: Archaeozoology
Northern Flagship Institute
Museum of Natural History (Transvaal Museum)
P.O. Box 413
Pretoria
South Africa
0001

Tel: 27 12 322 7632
Fax: 27 12 322 7939
E-Mail: Scott at tm.up.ac.za
Web: http://www-tm.up.ac.za
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