[Nhcoll-l] [MOGELIJK SPAM ! ******] Re: [Spam] Re: vials for storing insects in ETOH

Fri Nov 26 04:43:29 EST 2021

Silicon rubbers swell in low and non-polar solvents and its vapors. At a molecular level silicon rubbers exhibit a high segmental mobility resulting in a relatively high permeability. These papers might be of interest to understand the mechanism of action:

https://pubs.rsc.org/en/content/articlehtml/2015/tc/c5tc01927c

https://www.researchgate.net/publication/319043965_THE_INTERACTIONS_OF_PRESERVATIVE_FLUID_SPECIMEN_CONTAINER_AND_SEALANT_IN_A_FLUID_COLLECTION

Kind regards,

Dries

Andries J. van Dam<http://www.linkedin.com/in/andriesvandam> | curator-conservator

Anatomical Museum<https://www.lumc.nl/onderwijs/over-ons/anatomisch-museum/?setlanguage=English&setcountry=en> | Leiden University Medical Center | Building 3 (V3-32)
P.O.Box 9600 | 2300 RC Leiden | The Netherlands
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Scientific associate | Natural History Museum London | http://www.nhm.ac.uk<https://mail.lumc.nl/owa/redir.aspx?C=O7wgy__4qEq-bCzDQhMP7IpMG33lsdEIUTcpXTatWwljNFWdpbtnBKj-HeYnbumJrkd3hILExAk.&URL=http%3a%2f%2fwww.nhm.ac.uk%2f>
________________________________
Van: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> namens William Poly <wpoly at calacademy.org>
Verzonden: donderdag 18 november 2021 23:20:39
Aan: Callomon,Paul
CC: NHCOLL-new
Onderwerp: [MOGELIJK SPAM ! ******] Re: [Nhcoll-l] [Spam] Re: vials for storing insects in ETOH

I've also observed the swelling of the green and gray rubber stoppers that Doug mentioned.  The swelling is inside the vial where the stopper contacts the ethanol.  Could be the denaturants reacting with the rubber (not sure of the exact composition of these rubber stoppers).  Of course the entire stopper will swell if immersed completely in a larger container.  Swelling on both ends of the stopper could crack the neck of the vial[?].

As an alternate method of relieving pressure (instead of using hypodermic needles), one can use a dissecting probe and release pressure on the side of the rubber stopper (if the vials aren't too fragile); it's worked for me and others.

Bill

William J. Poly
Research Associate
Department of Ichthyology
California Academy of Sciences
55 Music Concourse Drive, Golden Gate Park
San Francisco, California 94118
wpoly at calacademy.org<mailto:wpoly at calacademy.org>
https://www.calacademy.org/scientists/ichthyology/wpoly

On Thu, Nov 18, 2021 at 8:51 AM Callomon,Paul <prc44 at drexel.edu<mailto:prc44 at drexel.edu>> wrote:
Just some additional thoughts to what everyone else has said:

- We have found that phenolic resin (the smooth, hard black resin used to make screw tops for smaller vials such as 4- or 6-dram ones, usually with foil or cone-seal liners) is not stable in ethanol; it leaches a brown stain into the fluid within a couple of years.
- We use small glass "micro-vials" in our dry and wet collections. In alcohol, we stopper them with natural cotton wool. This is finer than polyester batting and thus less likely to snag the specimen; if the plug is made by first rolling the wool into a sausage and then folding it double and pushing the butt end into the vial opening (like a Kielbasa, extending the metaphor) there are few open fibers facing the specimen. Rehousing some 1850s lots recently gave me a chance to test the cotton for strength and confirmed that it is effectively inert in alcohol, though not in air. See https://avanan.url-protection.com/v1/url?o=https%3A//www.researchgate.net/publication/308079611_An_alternative_to_gelatin_capsules_in_natural_history_collections&g=ZjBjOTg5ZTY2Mzg2NGQzNQ==&h=ODY1ODc4MTRhYjY1NDYzOGY2YTdjODc1NzQxNjFjMDEzNGJlMGMwMmY5NWZiYjYzYzk1ZjI2N2YyMmM4N2ZmNQ==&p=YXAzOmNhbGFjYWRlbXk6YXZhbmFuOmc6OTJjMTkyY2QxYmNiNzk5MTU2NDk3ZGVjNzVhOTg4ZjU6djE6cA==
Given that a vial is going to be submerged in ethanol, though, maybe one could use rolled paper as a stopper - perfectly stable, very cheap. Lollipop sticks (Chupa-chups and the like) are just rolled white paper, and expand slightly when wet - sliced up, they might make great micro-vial stoppers.
- We used to keep multiple lots in common jars, as Tonya proposed, and still don't automatically counsel against it. There are economic advantages in terms of space and material costs and the time-saving element of only having to check one lid for dozens of specimens, but there might be long-term issues with sharing fluid via permeable internal barriers, such as the migration of lipids, radio-isotopes and even DNA between lots that could one day give a false signal in analysis. Placing multiple lots in a common jar but giving each one an impermeable stopper keeps them separate and means that the surrounding fluid is simply a secondary safety measure in case the internal stoppers fail. However, the stability in ethanol of any post-1980s plastic compound across museum-scale time periods is still not guaranteed.

Paul Callomon
Collection Manager, Malacology and General Invertebrates

Academy of Natural Sciences of Drexel University
1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
prc44 at drexel.edu<mailto:prc44 at drexel.edu> Tel 215-405-5096 - Fax 215-299-1170

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