From: Alberto Novo (alnovo@inwind.it)
Date: 04/24/03-12:49:19 AM Z
> Also, how much sodium azide preservative per how much gum?
> Chris
>> As for the preservatives, I use sodium azide, and store the solution in
the refrigerator.
>>
>> Alberto
Sodium azide is more properly a bacteriostatic, that is it stops their multiplication instead of killing them.
I use it because I have it; it is odorless and about 0.1g/1000 ml is enough for the conservation.
Beware: it may explode if heated (it is used in the airbags), and it must not be mixed with heavy metals and their salts (copper, lead, silver,...) because the resulting compounds are extremely instable and may detonate.
I think (but I never tried) that the common disinfectants based on quaternary amines may be used with success.
To prevent not only fermentation (from bacteria) but also moulds, products as addictives for wall painting may be used as well. This also I never tried, as I have some gum solutions (gum+pigment) in my refrigerator that are more than one year old and look like freshly made, so I don't look for other improvements.
On the contrary, I find the conservation of gelatine solution more challenging, also because it must be heated every time before use and all the seizing operations are "dirty" from a biological point of view.
Alberto
http://spazioinwind.libero.it/albertonovo/
Alt-photo group in Italy:
http://www.grupponamias.com/
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