[NHCOLL-L:4412] Re: Lids for glass jars

[Dirk Neumann]

Depending on the fixation of your specimens, I would be careful with the 
resin-lined caps. Like with Bakelite, the problem is not the 
preservation fluid, but the fixative formalin (the paraformalin-polymer 
Bakelite is corroded by residual formaldehyde dissolving from the 
specimens and then evaporating from the preservation fluid). The same is 
likely to happen with synthetic resines, e.g. epoxy resine / 
polyurethane resine / unsaturated polyester resine, since all of them 
are polymerisation-polyaddition or polycondensation products with 
chemically instable chemical bonds in the long run .

Same applies for polar plastic polymers like polyvinyl chloride and 
plastics with a high amount of softeners; those lids will loose their 
softeners quite soon and as a result they will get stiff and brittle.

PE & PP are quite stable against many chemicals, it would be surely the 
best option you have.

You may also consider commercial twist-off glasses with metal lids; 
normally, there are two types of lids, one for fatty ingredients, one 
for sour / acidic (like mixed pickles). The latter ones have a thicker 
PE liner inside the lid which prevents the lid from rusting too fast. 
Since sizes of most of these lids are ISO-standardised, it should be 
possible to replace them the next decades (hopefully). Compared to the 
plastic lids in our collection, we didn't have any problems with the 
metal lids the last 15 years. The observed problems with the plastic 
lids however, is mainly based on the denaturing agent added to our 
magazine alcohol, and not on the ethanol itself.

Hope this helps

Dirk

 





John E Simmons schrieb:
> What sizes of jars are you looking for lids for? 
>
> I don't know what "pulp/vinyl" lids are either, but it might be worth 
> asking the manufacturer.  It may just be another version of polyvinyl 
> chorlide lids, which you don't want. 
>
> Polyethylene lids are fine if your lighting is UV shielded and you 
> avoid exposing the lids to sunlight, but the low-density PE lids may 
> allow too much oxygen permeance.  
>
> The "fluoropolymer resin-lined caps" sounds like it is probably a 
> rigid lid (similar to bakelite). What you want is a lid that is 
> slightly flexible (so that it will conform to the irregularites of the 
> jar and be more resistant to backing-off) and a soft enough liner that 
> you can tighten the lid down sufficiently.  I would avoid the rubber 
> lined caps as the rubber (if real rubber) will have a very short lifespan.
>
> You might consider asking for samples of the various types of lids.  
> You can test the plastic yourself for the presence of chlorides to 
> eliminate the PVC lids and you can get a better assessment of how well 
> the liners are likely to hold up.
>
>
>
> On Mon, Jul 27, 2009 at 11:12 AM, Gegick, Patricia, DCA 
> <patricia.gegick at state.nm.us <mailto:patricia.gegick at state.nm.us>> wrote:
>
>     Dear List,
>
>     I am attempting to purchase glass jars for alcohol storage of
>     freshwater gastropods and bivalves.  In reviewing my file on
>     containers, I note the following:
>
>             Some museums like TEF lined lids
>             Polystyrene lids are good if not exposed to benzene rings
>             Polyethylene is good if not exposed to UV light
>             “Bakelite” lids are not good
>     My mollusk reference suggests polypropylene lids with polyethylene
>     liners
>
>     The lid options I have are:
>             Pulp/vinyl (don’t know what a “pulp” lid would be)
>             Solid PE (polyethylene) lids
>             PTFE/LDPE  Poly-tetrafluoroethylene lids with low density
>     polyethylene liners
>             Fluoropolymer resin-lined caps
>             Polyvinyl-lined caps
>             Rubber-lined caps
>     PTFE-Faced LDPE Foam-lined Caps
>
>     Can anyone tell me if the PTFE lids would be appropriate and
>     similar to polypropylene lids?  Also what is “resin lined” and
>     will 70-80% alcohol affect this?  Thanks.
>
>
>
>     Patricia J. Gegick
>     Bioscience Collections Manager
>     Department of Collections and Research
>     New Mexico Museum of Natural History & Science
>     1801 Mountain Road, NW
>     Albuquerque, NM  87104-1375
>     Phone:  505.841.2867  Fax: 505.841.2866
>     email:  patricia.gegick at state.nm.us
>     <mailto:patricia.gegick at state.nm.us>
>
>      
>
>
>     Confidentiality Notice: This e-mail, including all attachments is
>     for the sole use of the intended recipient(s) and may contain
>     confidential and privileged information. Any unauthorized review,
>     use, disclosure or distribution is prohibited unless specifically
>     provided under the New Mexico Inspection of Public Records Act. If
>     you are not the intended recipient, please contact the sender and
>     destroy all copies of this message. -- This email has been scanned
>     by the Sybari - Antigen Email System.
>
>
>
>     Confidentiality Notice: This e-mail,including all attachments is
>     for the sole use of the intended recipient(s) and may contain
>     confidential and privileged information. Any unauthorized
>     review,use,disclosure or distribution is prohibited unless
>     specifically provided under the New Mexico Inspection of Public
>     Records Act. If you are not the intended recipient, please contact
>     the sender and destroy all copies of this message. -- This email
>     has been scanned by the MessageLabs Email Security System.
>
>
>
>
> -- 
> John E. Simmons
> Museologica
> 128 E. Burnside Street
> Bellefonte, Pennsylvania 16823-2010
> simmons.johne at gmail.com <mailto:simmons.johne at gmail.com>
> 303-681-5708
> www.museologica.com <http://www.museologica.com>
> and
> Adjunct Curator of Collections
> Earth and Mineral Science Museum & Art Gallery
> Penn State University
> 19 Deike Building
> University Park, Pennsylvania 16802-2709
> jes67 at psu.edu <mailto:jes67 at psu.edu>


-- 
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/