[Nhcoll-l] Fluid preservation jar lids

[Julian Carter]

I concur with Rob on this, plus it must be remembered that ethanol is only very weakly ionisable, has a wider pKa, and thus we have to be careful comparing acidity in an ethanol solution with that of a dilute water based solution as it is not necessarily a ‘like’ for ‘like’ situation chemically.

Best

Jules



From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Robert Waller
Sent: 17 August 2022 00:25
To: nhcoll-l at mailman.yale.edu
Subject: Re: [Nhcoll-l] Fluid preservation jar lids

Our field has conflated the idea of wood products becoming acidic over time with pure cotton (cellulose) becoming acidic over time. It is the lignin content of wood that becomes acidic, and in some cases additives to paper, that become acidic over time (through oxidation and/or hydrolysis). Pure cotton itself is not expected to become acidic over time except by transfer of acidity from adjacent components and even that is questionable. Certainly, in fluid preserved collections there are many components that will react with oxygen before cellulose gets a chance. These include residual formaldehyde from fixation, oils, fats, and other organic constituents  from specimens, and even ethanol itself – consider the wine into vinegar process.
Pure cotton presents no risk of acidification, although it may present problems of catching on complex surfaces.
Rob


From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu>> On Behalf Of Tom Schiøtte
Sent: Tuesday, August 16, 2022 7:35 AM
To: nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>
Subject: Re: [Nhcoll-l] Fluid preservation jar lids

Dear Lennart,

I am no biochemist, but my understanding is that cotton is chemically complex, but that the end result is rather to the alkaline than the acidic side. Somebody correct that if I am wrong. In alcohol samples, however, the real thing to worry about is that the alcohol itself becomes somewhat acidic when it over time absorbs CO2 from the air.

I have heard of synthetic cotton too. Let somebody experiment with that over 100 years and perhaps convince my great-great-grandchildren of its qualities.

Cheers

Tom



From: Lennart Lennuk <Lennart.Lennuk at loodusmuuseum.ee<mailto:Lennart.Lennuk at loodusmuuseum.ee>>
Sent: 16. august 2022 13:07
To: Tom Schiøtte <tschioette at snm.ku.dk<mailto:tschioette at snm.ku.dk>>; nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>
Subject: RE: Fluid preservation jar lids

Dear Tom,

Can you tell if there might be a probleem with acidity with cotton wool?
I have heard about alternative using of synthetic cotton.

Best!
Lennart

From: Nhcoll-l [mailto:nhcoll-l-bounces at mailman.yale.edu] On Behalf Of Tom Schiøtte
Sent: Tuesday, August 16, 2022 12:29 PM
To: nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>
Subject: Re: [Nhcoll-l] Fluid preservation jar lids

Dear Joosep,

At our museum we always used ordinary 100% hydrophilic cotton with satisfactory results for stoppers in the glass-tubes. Among other things it keeps its properties over very long time. We have experimented with other solutions, but they always proved to be problematic in some way.

Mind you, with the setup on your photo, use also a layer of cotton wool under the glass tubes to prevent them from breaking on the outer glass jar. And if you now tell me that the tubes and jars are some kind of plastic or PVC, please reconsider your choice. Glass and cotton have practically eternal life, while other materials have yet to demonstrate that.

Cheers

Tom

Tom Schiøtte

Collection manager, Echinodermata & Mollusca
Natural History Museum of Denmark (Zoology)
Universitetsparken 15
DK 2100 Copenhagen OE

+45 35 32 10 48
TSchioette at snm.ku.dk<mailto:TSchioette at snm.ku.dk>



From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu>> On Behalf Of Joosep Sarapuu
Sent: 16. august 2022 10:39
To: nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>
Subject: [Nhcoll-l] Fluid preservation jar lids

Dear all,
We would like to know which lid is the best for small jars for fluid specimens. We have an idea that when we collect (for excample small coastal specimens) in the same area and same date we can sort them out in the small jars and place small jars in the big jar (like in the picture) to save space and it will be comfortable to manage these. We will put alcohol in both jars, the small ones and big one also. But right now we do not know which is the best way to close the small jars to prevent specimens to fall out. Is some kind of cotton, or plastic or something else the best. Can somebody help us?

Sincerely,
Joosep Sarapuu
Estonian Natural History Museum
59031393

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