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<p class="MsoNormal">Hey all,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I asked a while ago for advice on how to deal with amber that has been stored in mineral oil. I received many helpful responses which basically boiled down to:</p>
<p class="MsoNormal"> </p>
<p class="MsoListParagraph" style="text-indent:-.25in"><span style="">-<span style="font:7.0pt "Times New Roman"">
</span></span>Attempt to remove the mineral oil using a mild soap and water</p>
<p class="MsoListParagraph" style="text-indent:-.25in"><span style="">-<span style="font:7.0pt "Times New Roman"">
</span></span>Possibly grind or repolish the amber</p>
<p class="MsoListParagraph" style="text-indent:-.25in"><span style="">-<span style="font:7.0pt "Times New Roman"">
</span></span>Embed the amber in epoxy ( Paul Nascimbene recommended “<span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:black">a high-grade glass conservation epoxy called EpoTek 301-2”. Other people mentioned reactions between the oil
and epoxy so definitely be cautious with materials and techniques)</span></p>
<p class="MsoListParagraph" style="text-indent:-.25in"><span style="">-<span style="font:7.0pt "Times New Roman"">
</span></span>Cut down to study if desired.</p>
<p class="MsoListParagraph"> </p>
<p class="MsoNormal">We haven’t gotten around to trying this yet but I figured I’d post the responses in case anyone else finds them useful. I have permission to repost from both Paul Nascimbene and Ryan McKellar.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:black">Hi Rhian,<br>
<br>
I hope I can be of some help. We have occasionally encountered this problem here at AMNH, particularly with a few historical specimens, and with Lower Eocene Indian amber specimens that were recently sent to us in this condition. Are the specimens in question
amber pieces containing fossil arthropods?<br>
<br>
I'm not sure that mineral oil can be completely removed from within the amber (depending on how deeply it has penetrated the material), but, in the case of amber with insect inclusions, the affected surface of the amber can be ground and repolished (removing
the oil), as long as the insect lies adequately beneath the penetrated surface. I might recommend first washing the amber gently with a mild soap and water (no solvents), especially if you have larger display specimens that are affected. If the amber cannot
be ground or repolished due to policy for the collection, then washing and thoroughly rinsing the piece may help prevent further damage, but the amber is still likely to deteriorate over time (see cons. doc attached).<br>
<br>
Here at AMNH, we treat amber containing arthropods by embedding the amber under vacuum in a high-grade glass conservation epoxy called EpoTek 301-2 . I am attaching three documents FYI.
<br>
<br>
I am happy to answer further questions. <br>
<br>
Best Regards, Paul<br>
<br>
</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:black">Hi Rhian,<br>
<br>
I read the rest of the thread on 'cleaning amber' in the nhcoll listserv today. Since the incident in the 90's with the original Type Sphecomyrma specimen, much has been learned about embedding amber specimens in epoxy, and we now use a higher grade epoxy
that takes longer to cure, but has never produced an exothermic reaction in my experience (EpoTek 301-2). I have used this glass conservation epoxy successfully on amber specimens that were coated with mineral oil (although I removed as much of the oil as
possible beforehand by grinding and polishing the contaminated surfaces). I suggest first trying this process on an expendable piece of amber that has either been immersed or coated with mineral oil.
<br>
<br>
Mineral oil will eventually fully degrade amber and likely ultimately compromise or ruin any inclusions the amber contains. On the other hand, embedding amber in a high grade epoxy like EpoTek prevents oxidation and also significantly improves viewing of inclusions.
<br>
<br>
<br>
Regards, Paul</span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:black"> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif"">Hi Rhian,</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif""><br>
Stacey Gibb forwarded part of the amber discussion that you have been having with Janet Waddington, concerning mineral oil storage. She figured I might be able to help out. When I went through the RTMP Grassy Lake collection, I didn't encounter any vials where
the specimens were entirely submerged in fluid. There were a large number of samples in the type room in glass vials that had a thin film of what appeared to be glycerine clinging to them. (This and sugar-water are the most common modern solutions used for
viewing inclusions, and will dry onto the specimens if they are not rinsed properly). To the best of my knowledge, glycerine does not react with plastic, but liquids like mineral oil and cedar wood oil haven't been used for quite some time (unless the specimens
were loaned to some oddball researcher, or predate the bulk of the collection, the timing seems strange for mineral oil). The quick-and-dirty way of figuring out if you are dealing with glycerine vs. mineral oil is to take some of the fluid and mix it with
water (glycerine should be soluble, given enough time, while mineral oil should be immiscible). If you do have mineral oil issues, there is very little that can be done without some risk to the amber. Probably the best long-term solution that comes to mind
would be rinsing the amber pieces in a weak solvent to remove as much of the mineral oil as possible, drying them extremely well, and embedding them in a stable epoxy like Buehler's Epothin. The problem that Grimaldi and Nascimbene (1997) ran into was their
epoxy reaching the temperature required to release the volatiles within the mineral oil that was stuck to their specimen. If small enough moulds are used for embedding (less than one inch, and with just enough epoxy to cover the amber piece) batch sizes should
be small enough that heat should not be much of an issue. These authors also mention that New Jersey amber is much more soluble than Canadian material, so Canadian amber is less likely to retain mineral oil within the amber itself. Ultimately, it will require
at least one test specimen to see if any of this will work. If you would like help with the embedding, just let me know -- we do this sort of thing with Canadian amber at the U of A pretty regularly.<br>
All the best,<br>
-Ryan <br>
<br>
</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif""> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif"">Hi Rhian,<br>
in the long run, I would strongly advocate embedding the pieces -- this and storing the specimens out of direct light is the only way to slow their eventual weathering. Many of the ROM specimens are difficult to study because the amber has significantly darkened
and has developed large fractures that obscure the specimens. This is pretty scary, given that the collection only dates back to the late 30's. The same problem exists but is reduced in the Canadian National Collection of Insects and Arthropods amber collection,
because most specimens were embedded early and only extend back to the early 60's. This said, most of the CNC material has been polished to expose the amber on at least two sides, so it will eventually share the same fate. I have attached the latest paper
on these sorts of concerns.<br>
<br>
The detergent idea is probably the gentler alternative to using a solvent, and would be better. We have had luck cleaning glycerine off of pieces using a very mild solution of "Sparkleen" (the residue-free laboratory glassware detergent) and then rinsing the
material in distilled or deionized water. If the glycerine or mineral oil has largely evaporated, it might take quite a long soaking to loosen whatever is adhering to the specimens. If it is mineral oil, I am not sure that a detergent will be enough to get
it off, but it is definitely worth a try.<br>
<br>
Hope some of this helps.<br>
-Ryan <br>
<br>
</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">The papers that were recommended are as follows:</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif"">Grimaldi, David and Paul Nascimbene.. “Appendix: Vacuum embedding and disintegration of the type of
<i>Sphecomyrma freyi</i>.” In “New and rediscovered primitive ants (Hymenoptera: Formicidae) in Cretaceous amber from New Jersey, and their phylogenetic relationships,” by David Grimaldi, Donat Agosti, And James M. Carpenter, 41-43.
<i>American Museum Novitates</i> 3208 (1997):1-43</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif""> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif"">Nascimbene and Silverstein. “The preparation of fragile Cretaceous ambers for conservation and study of organismal inclusions” in “Studies on fossils in amber, with particular
reference to the Cretaceous of New Jersey”. Ed. David Grimaldi, pp.93-102. 2000.</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt; font-family:"Times New Roman","serif""> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Bisulca, Christine, Paul Nascimbene, Lisa Elkin and David Grimaldi. “ Variation in the Deterioration of Fossil Resins and Implications for the Conservation of Fossils in Amber”.
<i>American Museum Novitates </i>3734 (2012): 1-19.</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> </span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:10.0pt; font-family:"Arial","sans-serif"">Rhian Russell</span><span lang="EN-CA" style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:10.0pt; font-family:"Arial","sans-serif"">Conservation Technician</span><span lang="EN-CA" style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:10.0pt; font-family:"Arial","sans-serif"">Royal Tyrrell Museum of Palaeontology,</span><span lang="EN-CA" style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:10.0pt; font-family:"Arial","sans-serif"">Box 7500, Drumheller, Alberta T0J 0Y0</span><span lang="EN-CA" style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:10.0pt; font-family:"Arial","sans-serif"">Phone: (403) 823 7707 Ext. 3306</span><span lang="EN-CA" style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
<p class="MsoNormal"><span lang="EN-CA" style="font-size:10.0pt; font-family:"Arial","sans-serif"">E-mail: <a href="mailto:rhian.russell@gov.ab.ca"><span style="color:blue">rhian.russell@gov.ab.ca</span></a></span><span lang="EN-CA" style="font-size:12.0pt; font-family:"Times New Roman","serif""></span></p>
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