Shell cleaning help

[paul monfils]

Yes that cowrie is certainly in need of some cleaning! The problem in removing this kind of calcareous encrustation is that it is composed of the same material as the shell - calcium salts - and therefore any chemical that will dissolve the encrustations will also dissolve the shell. So chemical cleaning methods are out. Only physical methods can be used on something like this. That having been said, it is possible, depending on the type of encrustation, that a pretreatment with bleach will loosen or soften the encrustations somewhat, making subsequent physical methods a bit easier. This is because such encrustations often have a small proteinaceous component, and the bleach will dissolve out the proteins though it won't dissolve the actual calcium salts. With or without pre-bleaching, physical methods must follow. If you have access to one, I would first try an ultrasonic cleaner, to see how much of the encrustation will be removed by that means. If any of it comes off, continue to use the USC for a longer period of time. After that, if some of the white stuff still remains, patient picking with a sharp tool or scraping with a small sharp blade is about the only way of getting the stuff off, bit by bit. Most likely the gloss of this shell is already damaged, and no matter how carefully you clean it, it won't look like a live-taken cowrie.

Now, the sea biscuit - The test (shell) of this animal is actually white. The dark color is due to a layer of microscopic brown spines attached to the test, and associated muscle fibers and other soft tissue. Using bleach removes all the spines and tissues, and leaves just the white test. However, if you want to keep the specimen "natural", it isn't difficult to do. I usually soak such specimens in formalin for a few days, then alcohol for a few days. But I realize not all people have access to formalin, and also it is smelly and irritating and somewhat toxic. If you do have formalin and know how to use it, I believe that gives the best preservation. However, good results can also be obtained using alcohol alone. In that case, soak the specimen in alcohol for about a week, changing the alcohol at least once, after the first couple of days. Ethyl alcohol is best but isopropyl alcohol is adequate. Avoid methyl alcohol, which is sold as shellac thinner. The alcohol concentration should be at least 70%. "Rubbing alcohol" from the pharmacy works satisfactorily.

Once the specimen is preserved in the alcohol, it can be removed, drained, and then dried thoroughly in a warm, dry area. Outdoors is good, weather permitting, but it can be dried indoors too. However, in specimens prepared in this way the spines are not too securely attached to the test, and tend to gradually fall off, especially if the specimen is handled much. So I use an additional procedure to prevent that. I remove the specimen from the alcohol, soak it in water overnight to remove the alcohol, then soak it in 10% Elmer's Glue-all (10% glue, 90% water) for a couple of hours, then drain and dry. The glue dries invisible, but strenghtens the spine-to-test attachment. Other brands of white glue, like Sobo Glue, are equally good. (Chemically this is polyvinyl acetate). If you use glue, dry the specimen on a non-stick surface like wax paper, so you don't end up with the specimen glued to whatever surface it is lying on.