[Nhcoll-l] PTFE tape on jars
Dirk Neumann
dirk.neumann at zsm.mwn.de
Tue Jan 14 02:32:02 EST 2014
Morning John!
I think (personal impression rather than something I could proof) that
deterioration follows the concept "similar dissolves in similar" (I am
not sure if this literally translation of the German "Ähnliches löst
sich in Ähnlichem" is common in English, too):
Parafilm is a polyolefin wax which is not that stable against organic
solvents, my impression is that if parafilm gets into contact with
long-chained hydrophobic hydrocarbonates, especially vaseline /
petroleum jelly, the parafilm wax starts to "melt" and turns into a
smeary waxy stringing substance. This type of deterioration is also
observed in combination with vacuum greases.
PTFE tape: we have a type of jar without threads, for these PTFE tapes
failed completely. For use in combination with metal lids / threaded
jars (as long as there is no way to get hold of the acid-resistant type
of metal lids which have stronger liners), I would prefer the teflon
inlays which also protects the lid against corrosion / chemical
reactions triggered from condensation inside the jar.
Removal of old silicone grease: thanks for pasting Simon's very valuable
link into this discussion! I never used silicon based greases in the
collection after devastating results from my initial testing with
various vacuum greases (dumping a chunk of the grease into our denatured
alcohol and comparing stability after 1 year). Since then, I always use
("my" most favoured and most appreciated) Alsirol grease produced by a
small company in Bamberg, Germany. Just hope they will never run out of
production, but as this fat is food safe and of prevailled usage in
small scale breweries in Upper Franconia, I am confident ;-)
To remove old silicone glue, you may also use (quite drastic, but works
just fine) a drilling machine with a soft & fine brass-brush-attachment
turning at moderate speed. Tried this methods with large old battery
jars with good results after receiving this tip from aquarium hobbyists
cutting & re-glueing large tanks. One needs to be well skilled in
free-hand operating of drilling machines, especially in combination with
fragile glass containers, of course, but it works pretty well and is
very time efficient.
All the best
Dirk
Am 13.01.2014 18:43, schrieb John E Simmons:
> Dirk,
> Thanks for your contribution to this discussion. Just to be clear, the
> recommended use of PTFE tape is to wrap it around the threads on the
> jar before the lid is applied, in order to help the lid seal better
> with the jar. PTFE is less permeable to the transmission of oxygen
> than Parafilm.
>
> I presume that the deterioration of parafilm that you describe is
> caused by contact with the old grease remaining on the glass? Do you
> have any idea what the chemical reaction is that causes the deterioration?
>
> The Teflon liners should work well--we can purchase several sizes of
> jar lids here with Teflon liners already in them.
>
> Concerning the removal of old silicon, Simon Moore pointed out to me
> that you can purchase a silicon releasing agent in liquid or spray
> form at many hardware stores in the US and the UK. These work with the
> methyl groups in silicon:
> http://www.dowcorning.com/content/discover/discoverchem/si-release.aspx?e=How+Silicones+Work
>
> Since Simon alerted me to the release agent, I have used the liquid
> form to remove old silicon seals from glass several times--you might
> want to try a silicon release agent on the silicon oil you mentioned.
>
> --John
>
> On Mon, Jan 13, 2014 at 2:18 AM, Dirk Neumann <dirk.neumann at zsm.mwn.de
> <mailto:dirk.neumann at zsm.mwn.de>> wrote:
>
> Dear Paul,
>
> we had bad results with PTFE tape because it didn't seal jars
> adequately even though tied thoroughly around the lids.
>
> Parafilm as Tony suggested works much better. You can easily
> remove it residue-free again, but be careful if wrapping parafilm
> around jars that are closed with ground stoppers / glass planes &
> grease (e.g. old battery jars): the parafilm will dissolve quickly
> into a rather sticky slime, which can hardly be removed.
>
> For twist-off jars with metal lids adding additional Teflon liners
> to be inserted in the lids might be an idea: colleagues in
> Switzerland use those with pretty good results for several years
> now (the website is in German, they don't offer a English version,
> sorry - But from the pictures you may get an idea what those
> liners look like).
> http://www.taxidermy.ch/p078000003.html?article_id=78000164&shop_action=detail
>
>
> I am not sure if these are available in the US, but these liners
> not only seal but also protect metal lids against evaporating
> moisture thus preventing them from rusting.
>
> For Le-Parfait jars etc. you can also add some high quality joint
> grease - but be careful and avoid any silicon based vacuum grease
> as it is nearly impossible to bring the silicon oil off the
> glasses after the silicon grease deteriorated (which happens
> within few years).
>
> Hope this offers some ideas ...
>
> All the best
> Dirk
>
> Am 10.01.2014 22:48, schrieb Callomon,Paul:
>>
>> Folks,
>>
>> At least 20 years ago (before my time here), white plumbers’ tape
>> was wrapped around the edge of the lids and onto the sides of all
>> the bottle and jars in a certain section of our alcohol
>> collections. This is the PTFE tape that plumbers use to seal
>> threads; it is thin, soft and non-adhesive. Presumably the idea
>> was to provide a secondary vapor barrier in addition to the jar
>> lid seal.
>>
>> We are now doing long-overdue major maintenance on this
>> collection, and are trying to assess the efficacy of this tape.
>> I’d be very interested to hear from anyone who (a) has used it
>> and can show it works (b) has used it and can show it doesn’t
>> work, or (c) who considered using it but decided not to, and why.
>>
>> *Paul Callomon*
>> /Collection Manager, Malacology, Invertebrate Paleontology and
>> General Invertebrates/
>>
>> ------------------------------------------------------------------------
>>
>> *Academy of Natural Sciences of Drexel University, Philadelphia***
>>
>> 1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
>> /callomon at ansp.org <mailto:callomon at ansp.org> Tel 215-405-5096
>> <tel:215-405-5096> - Fax 215-299-1170 <tel:215-299-1170>/
>>
>>
>>
>> _______________________________________________
>> Nhcoll-l mailing list
>> Nhcoll-l at mailman.yale.edu <mailto:Nhcoll-l at mailman.yale.edu>
>> http://mailman.yale.edu/mailman/listinfo/nhcoll-l
>>
>> _______________________________________________
>> NHCOLL-L is brought to you by the Society for the Preservation of
>> Natural History Collections (SPNHC), an international society whose
>> mission is to improve the preservation, conservation and management of
>> natural history collections to ensure their continuing value to
>> society. Seehttp://www.spnhc.org for membership information.
>
>
> --
> Dirk Neumann
>
> Tel: 089 / 8107-111
> Fax: 089 / 8107-300
> email: Dirk.Neumann(a)zsm.mwn.de <http://zsm.mwn.de>
>
> Postanschrift:
>
> Staatliche Naturwissenschaftliche Sammlungen Bayerns
> Zoologische Staatssammlung München
> Dirk Neumann, Sektion Ichthyologie / DNA-Labor
> Münchhausenstr. 21
> 81247 München
>
> Besuchen Sie unsere Sammlung:
> http://www.zsm.mwn.de/ich/
>
> ---------
>
> Dirk Neumann
>
> Tel:+49-89-8107-111 <tel:%2B49-89-8107-111>
> Fax:+49-89-8107-300 <tel:%2B49-89-8107-300>
> email: Dirk.Neumann(a)zsm.mwn.de <http://zsm.mwn.de>
>
> postal address:
>
> Bavarian Natural History Collections
> The Bavarian State Collection of Zoology
> Dirk Neumann, Section Ichthyology / DNA-Lab
> Muenchhausenstr. 21
> 81247 Munich (Germany)
>
> Visit our section at:
> http://www.zsm.mwn.de/ich/
>
>
> _______________________________________________
> Nhcoll-l mailing list
> Nhcoll-l at mailman.yale.edu <mailto:Nhcoll-l at mailman.yale.edu>
> http://mailman.yale.edu/mailman/listinfo/nhcoll-l
>
> _______________________________________________
> NHCOLL-L is brought to you by the Society for the Preservation of
> Natural History Collections (SPNHC), an international society whose
> mission is to improve the preservation, conservation and management of
> natural history collections to ensure their continuing value to
> society. See http://www.spnhc.org for membership information.
>
>
--
Dirk Neumann
Tel: 089 / 8107-111
Fax: 089 / 8107-300
email: Dirk.Neumann(a)zsm.mwn.de
Postanschrift:
Staatliche Naturwissenschaftliche Sammlungen Bayerns
Zoologische Staatssammlung München
Dirk Neumann, Sektion Ichthyologie / DNA-Labor
Münchhausenstr. 21
81247 München
Besuchen Sie unsere Sammlung:
http://www.zsm.mwn.de/ich/
---------
Dirk Neumann
Tel: +49-89-8107-111
Fax: +49-89-8107-300
email: Dirk.Neumann(a)zsm.mwn.de
postal address:
Bavarian Natural History Collections
The Bavarian State Collection of Zoology
Dirk Neumann, Section Ichthyology / DNA-Lab
Muenchhausenstr. 21
81247 Munich (Germany)
Visit our section at:
http://www.zsm.mwn.de/ich/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.yale.edu/pipermail/nhcoll-l/attachments/20140114/479beef8/attachment.html
More information about the Nhcoll-l
mailing list