Cleaning and maintaining your shells
There are several phases in cleaning and maintaining your shell collection. If some animal remains are still inside then they should first be removed. If you fail to remove all the animal tissue, the decomposition of any small traces of it will cause a disproportionate smell. Encrustations and any periostracum may need to be removed. The humidity conditions and the materials used for display can effect the conservation of the shell. Lastly, the shell may need a clean and gentle oiling from time to time to remove dust and restore its shiny lustre.
Phase 1. Getting the mollusc out of the shell
Remove the operculum if you want to preserve it and keep with the shell.
- Put the shell in a microwave inside an old sealed container for couple of minutes. If the animal is freshly dead then the expansion of gases will probably force out the remains. The smell in the microwave may dissuade you from using this technique.
- Put the shell in the deep freeze for a day or two in a sealed plastic bag with some water and then defrost slowly, lever the animal out with a dental pick and place outside on absorbent paper or sand, preferably with the suture channel down so that the juices will run out. Don’t try to pick the tissue out until it is totally defrosted or you will leave the frosted part inside. Repeat as necessary.
- Put the specimen in water and bring gently to the boil for 3 or 4 minutes, then take it out using a ladle and some material to protect your hands from the heat. Use a dental pick to leverage out the remains.
- If parts remain and a residual smell persists and your shell has a dull lustre, then put the shell in a 50% solution of strong bleach and water for a couple of days. Watch out for your clothes when you pick it out as the bleach will spurt out of the siphonal canal. Wash out and put in sand or on absorbent paper with the canal downwards.
- If parts remain and a residual smell persists and your shell has a shiny lustre then try pouring a small amount of bleach into the shell so that it internally retains the bleach or soak the shell in alcohol for a couple of days. Do not immerse shells with shiny lustre such as cowries and olives in bleach.
- Do not use bleach with any freshwater or terrestrial shell.
- If you have a small water jet gun try flushing the remains out after treatment. A large veterinary syringe without the needle is rumoured to work well.
- If all else fails, put the shell outside buried in some sand next to an ants’ nest and wait several weeks for ants to clean the shell for you. Cover it with sand and a large stone to keep animals from digging it up.
- If you are on vacation then such cleaning facilities may not be available. One option is to take a watertight plastic container and fill with strong alcohol, e.g. gin, and immerse your shells until you get them home.
Phase 2. Removal of the periostracum and barnacle materials
- To remove the periostracum, the woven jacket on some shells, put the shell in a 50% solution of strong bleach and water for a couple of days. Watch out for your clothes when you pick it out as the bleach will spurt out of the canal. Wash the shell out and put it on absorbent paper or in sand with the canal downwards and let it thoroughly dry.
- Use a dental pick after the bleach bath to gently remove any encrustrations.
Phase 3. Displaying and looking after the shell
- Try to display the shell away from strong sunlight and protect it from the effects of UV light.
- Choose a place with low humidity.
- Catalogue the shell and attach a small label to the specimen in a suitable place.
- If the shell is looking dull, give it a soft dust and apply a mineral or baby oil to the shell, rubbing lightly in; remove any excess and dry on absorbent tissue. Liquid paraffin oil tends to evaporate more easily and many collectors use it. Make sure the surplus oil does not stain your display case. Never oil a damp shell.
- If you wish to apply long-term conservation techniques then avoid putting on an acid-based paper label, and try not to touch it too much. Humidity combined with certain woods will give off acid vapours which results in a milky effect on the shell called Byne's disease. Shells should be treated by soaking for a couple of days, washing with a toothbrush, thoroughly drying and applying a light coat of oil. Remember to adjust conditions to remove the cause of the disease.
There is a helpful article by Paul Callomon about Byne’s disease on the Conchologists of America website.