PRINTING FROM NEGATIVES RA-4 PROCESS From Frank White (Area 13).

Not having made any recent contribution to the newsletter, I thought it might be a good opportunity to report on my experiences with the RA-4 process and in particular with L. H. Edwards formula for developing RA4. Papers.

Historically, I have used practically every known colour process from Agfa colour prints to Eka print - 3, & variations there of, with various home brews that have been published from time to time. To be honest, results have been like the curates egg Good in Parts or at times. It seems that the mix or shall we say the pH is critical, and conditions, like ambient temperatures, timing and process temperatures must be the same and repeatable to enable the filtration to be right and finally the negative must be developed out without any negative or positive x-overs of density curves. If there are then you will never get it right.

In fact, after some time I gave up, the task was too onerous. I tried Cibachrome, it was alright but it wasn`t so satisfying as the prints all appeared too contrasty.

So it was with some heart searching and trepidation, I decided to try R.A.4 process. The only problem seemed to be the short developing time. Could I manage it in the darkroom with my Drum Processor. I started with 25 sheets of Tetenal `Work` colour paper 10" x 8" and a 2.5 Litre Kit of Jessop chemicals.

The `Work` RA-4 paper of high quality on a polythene-coated base, for the production of colour prints from colour negatives and it can be processed in dishes, drums or machines. It is available in three surfaces, Glossy, Lustre or Semi matt. I have constantly used glossy.

Exposure, A colour enlarger, with a stabilised power-supply, colour, filter system negative or positive is required.

Processing chemicals for R.A.4, the best results are obtained with a solution temperature of 30C - 40C, this makes finding the correct filtration much easier. The chemical Kit from Jessop was manufactured by Photochem, and is suitable for processing all colour papers compatible with the R.A.4 process. It supersedes the old EP2 process.

It is especially suitable for processing systems incorporating drums or a one shot basis and it can be used for deep tanks.

The information included in the pack includes Storage life, and mixing instructions etc. Processing guide, temperatures & other information, and finally a trouble-shooting guide.

Finally, Full instructions on how to make your first colour prints, how to modify the filtration and exposure.

I found that the temperature was by no means critical and the error on developing time could be as much as 10secs over a range of 10C.

This factor alone was very acceptable, and allowed for filtration in room temperatures and avoided the use of water baths to ensure correct temperatures, of +/- «C.

I made up Solutions apart from Bleach-Fix in volumes of 250mls and found that I could process 6 No`s 10" X 8" prints in the 250ml developer solution i.e. 24 No`s 10" x 8" per Litre.

Later a Volume of 250ml Developer Solution was to give 12 prints i.e. 48 10" X 8" per litre, I think that is a little too many, as I found Filtration was becoming unstable & inconsistent. Bleach/Fix was coping easily with this volume of paper.

By this time, the developer (in the Kit) had been opened 6 months, and a Green cast formed on a print with some fresh developer solution, a sure sign of oxidised developer. The problem was solved using (a) 1.25 gms of ED4 initially and later reduced to 0.75 gms of CD4 i.e. 3 gms/Litre of CD4, with the other chemicals.

Sensimetrially there was very little difference in the filtration and the Filtration remained in the range of 80: 70: 00= +/- 10% of filter densities.

By this time I had grown confident and some of my pictures were begining to appear in the colour section at club competitions and winning, and some have been published, so time now for more experimenting.

This time lets try Lawrence Edwards Formula. First of all get the chemicals, some I had, some were new. Applications to John Pearle for Supplies.

A slight amendment has been made to the formula given on page 10, issue 82.

After all the ingredients have fully dissolved, add Part 1 to Part 2 and make up to 1000 ml. pH at 27C should be 10.4. I found it was necessary to add about 2.5 ml of Potassium Hydroxide, in order to get the right pH.

Shelf life. The concentrates above tightly closed and protected against oxidation with Tetenal Protectan were found to be excellent after 6 months and partly used working solutions similarly protected still gave good results after a month of intermittent use.

Capacity of the working solution above is approximately 40 sheets of 10"x8" colour paper.

Fixing. As there was plenty of Bleach/Fix solutions left over from previous Kits of R.A.4, these were used extensively until exhausted.

The process used was identical to that prescribed by Photochem and is given below, for drums, deep tanks, dishes or trays.

Note: The minimum developer time is 45 secs, less than this will result invariably with uneven development. In addition development time can be increased which tends to improve stability, but may require small changes in exposure and filtration compared to standard development times & temperatures.

Although I have not used any D.I.Y Bleach/Fix with R.A.4 paper I can see no reason why the formula given for E.P.2 paper by L. Edwards cannot work.

Finally, I would add one tip that I learnt from scrutinising a catalogue and can be of use to R.A.4 printers.

How to tell if your developer or Bleachfix is going" off". Take fresh sheet of colour paper, Adjust, enlarger to fully cover paper and add basic filtration say 50. 50. 00. Stop down lens to F8 & timer for 10 secs. Remove paper & cut in half. Expose one half for 10 secs, return the unexposed portion and then process both.

If the unexposed sheet is yellowey or magenta i.e. not white then the Bleachfix is off, and if the exposed sheet is bluish or not black then the developer requires replacing.

Note: Heading photograph of dog via Mrs. Salmon's Digital camera (C.R.C. Editor)