[Nhcoll-l] PTFE tape on jars

[Dirk Neumann]

Hi John,

for sealing battery jars I strongly recommend the Alsirol grease; inside 
Europe it is also distributed via VWR (which is operating as major 
retailers inside the US, too), but I am not sure if they could channel 
internal orders from the US to the European branch.

The advantage of the Alsirol is that it coarse grease that you can built 
up to equal out the uneven surface of those jars. This grease film stays 
very stable over the years, I used this method to seal all our shark & 
ray jars with pretty good results (compared to the former petroleum 
jelly sealing, which, after short time attracted evaporating moisture 
and started flowing down the jar ...).

Yes, there is a large variety of silicones available, but I always would 
avoid them for the mentioned reasons (one additional is that you have 
the cut the jars open again, with some colleagues breaking the stoppers 
on this occasion etc...).

Just to add to Dries' email: if possible, try to get PE liners inside 
plastic lids. Some denaturing agents corrode plastics quite fast.

All the best
Dirk


Am 14.01.2014 16:06, schrieb John E Simmons:
> Dirk,
> "Ähnliches löst sich in Ähnlichem" in English is "like dissolves 
> like." Its good to know the German phrase.
>
> Thank you for your detailed speculation on the problems with parafilm. 
> I think we all agree that the Teflon liners generally work best, when 
> they are available.
>
> Your comments remind me again how much the materials used to make 
> metal and plastic lids vary from one country or region to another. I 
> have also encountered these differences working with collections in 
> Latin America. The basic lesson is that the best solution to a problem 
> for one collection is not always the best solution for another 
> collection. It each case, it is important to understand the locally 
> available materials, to know exactly how the lids fit (or do not fit!) 
> on the jars, and to devise good strategies based on the materials you 
> have to work with.
>
> Silicon is another good example of a material that varies widely in 
> its composition. I try to avoid silicon greases for the reasons you 
> have explained.
>
> In the US we can buy some silicon-based caulking compounds designed 
> for use around sinks or for outdoor application that work reasonably 
> well to seal jars. I have attached an MSDS for one such product 
> (Spectrem) that I have used to re-seal old battery jars.  Can you get 
> similar products in Germany? There is, of course, one serious 
> caution--as Dries van Dam has frequently pointed out, silicon is not 
> as resistant to oxygen and water vapor permeance as some other 
> materials, but for many applications it is easier to work with and 
> replace.
>
> --John
>


-- 
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/