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Discussion in 'Alternative Processes' started by Mustafa Umut Sarac, Oct 4, 2013.
I found this chemical at a recipe of emulsion. Is it toxic, hard to find ?
Not something you want to be playing with!
Why it is used at solgel process at bR emulsion ? Is it possible to replace it ?
TEOS is a volatile liquid and an irritant to mucous membranes and the skin. According to the MSDS it is not particularly toxic.
Why does it necessary to use sol gel step after gelatin step when preparing emulsion ?
2.2.2. Preparation of sol-gel matrix
Tetraethoxysilane (TEOS) were used as precursors for the sol-gel glass. TEOS (7 ml), 3.0
ml of distilled water and 0.1 ml of 0.04 M HC1 were mixed together and sonicated for 20
min. The resulting product was diluted with an equal volume of distilled water. The resulting
mixture (0.5 ml) was mixed with 0.25 ml sodium borate buffer solution (pH 9) and (0.1 ml,
0.2 ml) bR solution to create a film-forming solution. Triethanolamine (TEA) was chosen as
sensitizing additives. The concentration of chemical additives was in the range of 0.01–0.4
M. For the preparation of chemically modified films, bR solution was mixed with TEA,
before mixing with the sol mixture, and afterwards 0.02 ml of the bR-chemical additives
mixture was added to 0.12 ml of the sol mixture [7,8].
Go here: http://en.wikipedia.org/wiki/Tetraethyl_orthosilicate to see that it is used as a crosslinking agent. That means that it is a hardener and as such can be harmful to you much as formalin and other hardening agents.
Do silver gelatin emulsions require such hardeners ? If we pass this step , do protein gelatin emulsion stay soft ?
All Silver halide based photographic systems that are intended for wet processing use a hardener. The type of hardener varies from company to company. All emulsions are hard, but they swell giving the effect of a degree of softness.