It is some
time since I have made an active contribution to the newsletter. In fact not
since I was able to to recommend some modifications to the E6 formula which
resulted in the official club recipes. I still use a variant which continues
to give excellent results. However, I find the Kodak Elite tends to give
very good but warm results, sometimes possibly slightly purple. On
contacting Kodak they "sort of admitted" that this film is warm.
They sent me some professional films including "Panther" to try
free of charge - very nice of them. I will let you know the results later.
Any way enough of this digression and back to the RA4 process.
This
process is, of course, that now used by all the labs for prints and was
presumably aimed at greater speed of throughput (it replaced the EP2
process). It can be used at home and kits and paper are readily available.
The paper is actually cheaper than the EP2 was! The RA4 paper is based on a
silver chloride system rather than bromide. The developer is also quite
different. Weighers and mixers should have no problems with this. The
formulae do seem to be largely in the public domain thanks to EC legislation
on safety data. These sheets list the chemicals used. The following formula
is probably not far off the official one:
To make 1
Litre of working developer:
Part 1
Water 400 ml
approx.
Anticalcium No.
5
2g
Potassium Hydroxide Solution 50% by weight
1 ml
Potassium Carbonate
26 g
Potassium Sulphite Solution 45% by weight
1.5 ml
(or sodium sulphite solid)
0.8g not tried but should be O.K.)
Triethanolamine
17 ml
N,N diethylhydroxylamine 85%
7 ml
Part 2
- mix the following in a separate container:
Water
100 ml
Lithium Chloride
2.1 g
Colour developer CD3
8 g
When the
solids have fully dissolved, add part 2 to part one with stirring and then
make up to 1 Litre with water. The pH should be 10.4.
Annticalcium
No.4 (as used for E6) can probably be used in place of No.5 but it may then
be necessary to reduce the potassium hydroxide amount to get the right pH.
It is not
known how long the ready-made developer keeps. Some I made before Christmas
contained crystals in January. However, it was exposed to some very low
temperatures, in my garage.
The
official RA4 bleach/fix (blix) uses a new chemical probably to gain speed
(ferric ammonium DPTA or 1.3-diaminopropan-2-ol N,N,N,N-tetraacetic acid).
However, I have found that the EP2 type blix works satisfactorily as
follows: 11.
To make
1 Litre of working blix EP2 type:
Water
700 ml approx.
Ammonium Thiosulphate Solution 60% by weight
150 ml
Sodium Sulphite
23 g
Ferric Ammonium EDTA solution 50%
75 ml
EDTA acid
1 gm
Acetic acid
enough to reduce the pH to 6.5 – 7
Water to make 1 Litre.
The
processing conditions using a Jobo CPE2 are as follows:
Drum
rotation
2
bath temperature
35C
Warm the drum containing exposed papers in CPE2 3
mins
Developer RA4 at 35C in bath
40
seconds plus 10 - 15s to drain
Stop bath (3% acetic acid)
20
seconds plus 10s to drain
Rinse (warm water 30 - 35C 400ml approx)
Twice - 1 minute approx.
Blix EP2 at 35C in bath
1
minute 50 secs plus 10s to drain
Wash (warm water 30 - 35C 400ml approx)
10
minutes ? 4 - 5 minutes approx)
Final rinse - deionised water (optional) 1
minute approx.
Tetenal
glossy paper (25, 10" x 8" sheets, £10 at Jessops), probably made
by AGFA, has been used successfully. The typical filtration is different to
EP2. If this is not taken into account when changing from EP2 then red
results are obtained. With the correct filtration perfect results are
achieved. Some trials will be required.