Carole,
I use a brush or just my fingertips to liberally apply a coating of food-grade silicone oil (without any other agents mixed in and not silicone grease) to the surface of the shell and then leave the coated shell in a plastic bag for at least 24 hours to allow the silicone to penetrate into the pores and saturate the outer layers of the shell via capillary action. Once the waiting period is complete, I rinse off the excess silicone oil with tap water to the point that the shell no longer feels slick or greasy. I then just blot or wipe off the excess water and place the shell in the shade. The remaining silicone does not evaporate, or does so only extremely slowly, and provides the "moisture" that should prevent the shell or periostracum from drying out and cracking. This method also brings out the colors of very dry old shells, masks small chafe marks and scratches, and does not cause yellowing with time.
Aloha,
Dave Lum
-----Original Message-----
From: Conchologists List [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Sunday, December 14, 2014 10:48 AM
To: [log in to unmask]
Subject: Re: [CONCH-L] Preserving Pen Shells
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 magnetâ€. 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
>
> ----------------------------------------------------------------------
> [log in to unmask] - a forum for informal discussions on
> molluscs To leave this list, click on the following web link:
> http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
> Type your email address and name in the appropriate box and click
> leave the list.
> ----------------------------------------------------------------------
>
> ----------------------------------------------------------------------
> [log in to unmask] - a forum for informal discussions on
> molluscs To leave this list, click on the following web link:
> http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
> Type your email address and name in the appropriate box and click
> leave the list.
> ----------------------------------------------------------------------
>
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
----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and click leave the list.
----------------------------------------------------------------------
----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs
To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and
click leave the list.
----------------------------------------------------------------------
|
