Re: Autochromes
OLIVO (olivo@iss.nus.sg)
Tue, 19 Sep 95 08:50:13 SST
I recall reading about the process. As far as I remember, you divide some
potato starch grains in three equal amounts, and you dye them red, blue and
green, such that the grains are still well separated. The dye must be
water-soluble, but perfectly alcohol-insoluble. You mix the grains
together, and some carbon powder too, to fill in the gaps between grains.
The mixture is then mixed in a alcohol-based transparent paint, which is
coated on some perfectly clean glass. A silver-based emulsion is laid on
top. Both coats must be very thin, particularly the starch one which should
be one-grain thick. Exposure takes place throught the glass and thus
through the grains, to give the colour separation.
I can't recall, but quick reasoning says you should develop, then bleach,
then expose to white light, then develop again and fix to produce a
positive. Is this right? Hope this helps- the whole process is supposedly
quite tricky.
O
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Olivo Miotto
Institute of Systems Science,
National University of Singapore,
Heng Mui Keng Terrace, Tel: +65-772 6644
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Email: olivo@iss.nus.sg
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