Along with the Photoworld adverts that Roy Salmons sent
me was some advertising material from Agfa about their latest .Agfacrome-
Speed the one shot, one bath process for Colour Prints from Slides. When
applying to selected dealers you are automatically rnade an Agfa -
Darkroom member. and receive a membership card along with information
leaflets about using all Agfa products. These information sheets are
excellent, and there is a well produced magazine (Agfa-Darkroom News).
Cant be bad for free and you get the benefit of any discount offers that
crop up from sales promotions. If you are interested write to PHOTOWORLD,
7. Queens Road, Craig -Y- don, Llandudno, Gwynedd, LL3 1AZ or
Tel. (0492) 76406, All C.R.C. members are welcome to join the Agfa-Darkroom.
For most of us the main interest will be
in the new revolutionary Agfachrome Speed, the one bath reversal
process. I myself know little about it, but Oliver Barron gave an
interesting write up in his Local Newsletter for May & June
1983. This will give you a fair idea of how it works...... This article
stems from communication between Oliver and Area 20 member Reg Gunn who
passed on information from an item seen in an American Magazine “PHOTOGPAPHY”.
AGFACHROME-
SPEED is a new colour material to make prints from slides using a single
solution, with hardly any time & temperature control. lit also works
as an in-camera positive print film.
Dr. Gareis of Agfa gave a processing
demonstration at Photokina in an improvised darkroom. Pre-exposed sheets
of the new material were loaded into special processing holders that
kept the picture light-tight but immersible. They were used in clear
acrylic plastic tanks, instead of a normally necessary 90 secs. of
darkness. We saw a positive to positive colour printing system where
temperature could be judged with one~s elbow and timed by counting
potatoes.. and watch colours form from light pastels to vividly
saturated hues in full room illumination. Moreover, contrast control is
by addition to the strongly alkaline activator. (Processing solution).
Briefly, this is how it works.
Agfachrome-Speed uses a diffusion—transfer process, in which the
unexposed parts of the colour image travel from layers to a receiving
layer. The material contains three colour—sensitive sender layers. In
the back-to-front exposure direction these are blue sensitive (yellow),
green sensitive (magenta) and red sensitive (cyan) labors.
Each of these layers contains
light-sensitive silver halides and developing agents. Exposure causes
the silver halides to develop when activated by the alkaline processing
bath and the development of this silver releases oxidation products that
anchor the dyes in place, so that they do not contribute to the image.
Only unexposed dye stuff is able to travel from the senders to the
receiving layer.
If a part of the picture receives no
exposure at all - e.g. a
very dark shadow area... all the yellow, magenta and cyan dyes travel to
the front situated receiver layer, forming blackness. A part of the
picture exposed by white light (which means light of all spectral
colours) makes the silver within each of the three layers developable
and this in turn causes the three colours to remain in place. We now see
a white area in the print which has a white pigment layer right behind
the --------- layer.
Colours are formed by anchoring the dye
of one layer while the other two are able to travel to the receiving
layer. Thus, red light exposure traps the cyan dye and we see red
because of the yellow & magenta dyes that travel to the receiving
layer. Similarly, green exposure anchors magenta, permitting yellow
&cyan dyes to make a green patch. Blue light traps the yellow,
allowing magenta & cyan to produce blue.
These principles are identical to those
used in Polaroid & Kodak instant films, although specific technology
is not. Agfachrome-Speed uses “new & complicated” technology.
The only thing it has in common with Polaroid is that the colour dyes
diffuse from the negative layers to the positive layers.
In
the Agfa material, the sender & receiver layers being combined in a
single sheet, there is nothing to peel apart and drop on the floor. The
processing involves a 90 sees. Immersion in the specially brewed Agfa
activator, who. se most active chemical is Pot. hydroxide. After this,
lights can go on and there’s a five-minute wash in running water.
Temperatures can vary from 18-24C without affecting results.