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> It occurs to me that in photo silkscreening you apply an emulsion
> (Diazo) to the screen, let it dry, and expose a negative to UV. Water
> is used to wash off the unhardened emulsion. Does anyone know what
> chemistry is used in this type of emulsion/sensitizer?
>
> How similar is it to Dichromate processes?
>
> If it's different could these chemicals be used as an alternative?
Hei, Macy!
Some silkscreen emulsions, like Diazo, are based on dichromates. There
are several types of new waterbased polymer emulsions, which are
intended to be used on frames/screens for printing on textiles ( like
Aquasol from Murakami Screen. co.ltd in Tokyo ). I have been using these
directly on different surfaces with additions of colorants and pigments,
both contact printing and projecting from a slide. One can add the color
inside the emulsion without blocking it for light, it can be sand
blasted or used as a stencil for pigmenting the background. The problem
is that these emulsions are developed for screenprinting and are
therefore very high contrast. I have used raster negatives, when details
were important. One can get very fine raster in QuarkPrint, which is
only seen with a magnifier. It is not seen on big scale enviromental
work. Traditional photographers will probably make grimaces on use of
raster, but it all depends on what you are after. Try it, it is fun!
Galina. (galina@online.no)