In addition to what has already been opined, I will direct folks to the
following paper which I just came across in my files...
The effects of relative humidity on mollusc periostracum and the use of
coatings to prevent loss. Joanna Morton. Collection Forum 20(1-2): 67-82
(2006).
This journal is published by the Society for the Preservation of Natural
History Collection. A link to the paper is
http://www.spnhc.org/media/assets/cofo_2006_V20N172.pdf
scroll down to page 78 of the PDF.
> Thanks Charles,
> Should have looked at my copy first. Your book answers most questions
> fully.
> Thanks,
> Carole
>
>
> In a message dated 12/13/2014 9:09:03 P.M. Eastern Standard Time,
> [log in to unmask] writes:
>
> Carole,
>
> I have have kept a number of thin walled Viviparidae and Pyganodon in
> ziplock bags without any other treatment. They have held up well for the
> past 10 years. A few which I did not put in ziplocks (an oversight)
> cracked within a few months.
>
> The ziplock bag, while permeable to moisture, isolates the specimen from
> rapid changes in relative humidity and seem to protect specimens
> reasonable well without "contaminating them with various chemical.
>
> On the other hand, if the specimen is going to be part of a display or
> one
> that will be handled by people, then some of the preservation techniques
> mentioned would be worth a try.
>
> I also offer the following which appeared in Chapter 2 of The Mollusks:
> Aguide to their collection, study, and preservation
>
> Animal and vegetable-based oils will become rancid with time and should
> be
> avoided. Silicon oil is a relatively inert substance. Its stability, lack
> of odor, and safety profile have made it a substance that people are
> comfortable using. The silicon oil is cut with naphtha or mineral spirits
> 1 part to 2-4 parts. Shells are dipped into this mixture and then placed
> on a flat surface. The solvent evaporates leaving behind a thin coating
> of
> silicon. If diluted appropriately the amount of silicon oil remaining
> should not leave the shell feeling greasy or tacky. Too much oil makes
> the
> shell slippery and a “dust
> magnet”. Mineral oils can be used in a similar fashion.
>
> A number of collectors have used a solvent called WD-40® to brighten the
> surface of a shell or to preserve the periostracum. WD-40 is a petroleum
> distillate. Some collectors dilute it 1 part to 3-4 parts naphtha or
> mineral spirits and then dip their
> shells into this solution. Others use the WD-40 full strength. We do not
> recommend WD-40 for one preservational aspect - it is a proprietary and
> secret formula. Such mixtures are of unknown composition and can be
> changed at any time. Thus, you are
> never certain what you are putting on your shells. If you are going to
> apply a coating to your shells, you do not want to apply it full
> strength.
> This full strength coating will often make the shell tacky and slippery.
> Many collectors dilute the oily substance with naphtha or mineral
> spirits.
> Diluting the oil one part to three or four parts of solvent is often
> sufficient. When the solvent evaporates, it leaves behind a thin coating
> of the oil. Also, the thinned oil is able to penetrate into the shell
> deeper than the full strength oil would. When using solvent, make sure
> there is adequate ventilation and no sources of open flames. While
> naphtha
> and mineral spirits are relatively low toxicity, they can act as
> respiratory irritants. They are also flammable, thus no sources
> of flames or sparking should be present.
>
> Clench (1931) described a process of mixing paraffin with xylene. Place
> 120 g (4 ounces) of paraffin in 300 ml (10 ounces) of xylene. Warm this
> in
> a water bath to dissolve the paraffin in the xylene. Shells are dipped
> into the solution and then placed
> on a flat surface to dry. The xylene will evaporate leaving behind a thin
> coating of paraffin. Remember that xylene is flammable so avoid open
> flames. Xylene is also a respiratory irritant, so this method should only
> be performed in a fume hood or a well ventilated area such as outdoors.
>
> You should also keep in mind that many collectors and most museum workers
> apply no surface coating to shells. Generally, if you keep the
> temperature
> and humidity level of your storage area within a range of 16-21ºC
> (60-70ºF) and 50-55% relative
> humidity, there should be no concern with the periostracum peeling (See
> Chapter 5, Archival and Curatorial Methods). Also, there is nothing wrong
> with a slightly faded, pristine shell as opposed to one that is shiny but
> chemically adulterated.
>
> Clench, W. J. 1931. A preventive for the scaling of the periostracum.
> Nautilus 45: 30-31.
>
>
> Regards,
> Charlie
> .................................................
> Charlie Sturm
>
> Treasurer
> American Malacological Society
>
> Research Associate - Section of Mollusks
> Carnegie Museum of Natural History
> Pittsburgh, PA, USA
>
> Associate Professor - Family Medicine
> Fellow-American Academy of Family Practice
> Fellow-Academy of Wilderness Medicine
>
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Regards,
Charlie
.................................................
Charlie Sturm
Treasurer
American Malacological Society
Research Associate - Section of Mollusks
Carnegie Museum of Natural History
Pittsburgh, PA, USA
Associate Professor - Family Medicine
Fellow-American Academy of Family Practice
Fellow-Academy of Wilderness Medicine
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