From The Horse's Mouth
By Ron Knowles
IN RESPONSE TO MY LETTERS I have received much useful information regarding the processing and handling of Konica, Fuji and 3M reversal films I contacted each of these manufacturers and Mr John Davies of Konica rang me on the very afternoon he would have received my letter Mr Davies thawed a great deal of interest in the C R C. was it a purely post club or did we have meetings, he asked. After giving him a run down of the Club’s activities we discussed a few points of the processing techniques and he did confirm that the pH values of the two developers I mentioned
9.65 (Dl ) and 11.75 (D2) which are around the normal for our home brews would be within the acceptable tollarances. So we are quite obviously off the right lines.
One point he made which has been something we in the club have discussed from time to time concerns the use of the developers for different make of film. Mr. Davies was emphatic that the there would be a change ‘in the solutions from the dropout into those solutions which varies with different emulsions. So obviously, even if the developers work for different film ‘first time round that chance your arm by using the same solutions again with a different film . That is the advice anyway, from a top Konica man.
My mention of the annual get together at Didcot had him Interested. I know Didcot well he said and intimated that he would be quite happy, to attend and ‘put on a show’. That seemed to take us into the Publicity Officer’s territory so. I phoned Tony Chuter immediately giving him all the ‘gen’ and presumably he would have taken it from there.
So it’s quite likely there is further news on this development elsewhere in this issue.
From the 3M Company I received an extremely helpful letter from Mr. Kevin Langman of their Technical Services Department, together with Data ‘Sheets dealing with their reversal film range. Also included was a reprint of a review by George Ashton used in the British Journal of Photography dealing with the 3M 400 ASA film. My query was mainly concerned with the green cast which has been so evident in the 3M films I have processed and I understand other members have also been~, plagued with the same problem. Mr. Langman suggests that in order to isolate the problem tests be carried out replacing each chemical bath in turn with standard Kodak chemistry. He also suggests that the reversal bath’ is replaced first, as under activity at this stage normally results in a green overall cast.
This company’s Data Sheets on the ASA 100 and 1000 films give no indication of the pH values and development times are mentioned to fly in relation to the Dl and gives 6 minutes as normal, with 9 minutes for one’-stop underexposd. Other than that they mention only that normal Kodak E6 chemistry be employed. The British Journal of Photography review is most glowing in its praise for the quality, fine grain and excellent colour rendition attained with the 400 ASA version. Of course the films on test were exposed under controlled condition’s and processed in a well maintained E6 line of a professional processing laboratory
So we shall, of course, have some difficulty attaining that standard. Still members have achieved excellent results before we shall again. But the green cast of 3M film does seem to present one of our more difficult challenges. And I must say the ‘3M range Is something of a challenge how does one get rid of that dratted green cast? This is something I’ll be working on during the next few months or, hopefully weeks.
Then from Fiji came that company’s film processing manual a fine affair comprising a bumper package of loose leaves, on quality art paper, contained in a loose leaf binder and dealing with every conceivable aspect of processing reversal film though aimed primarily to the commercial ‘endless belt’ system. However there is much of value and interest to us who work in the kitchen sink’
For instance Fuji give a table of pH and specific gravity values for each of the baths used in their CR 56 processing solutions Dl pH 6.65 (sp.gr. 1.065 Reversal pH 5.75 (ap. gr 1.014) D2 pH 11.9 ( a little higher than we would normally use) (sp.gr. 1.038) conditioner pH 6’2 (sp. gr. 1.010) Bleach pH 5.65 (for 6 minute bleaching) or 5.60 (for 4 minute bleaching) sp.gr. 1.131 or 1.156) Fixer pH 6.6 for either 2 or 4 minute fixing. sp.gr. 1.055 2 to 4 minute fixing.The life of Dl and reversal baths is given as one week (without a floating lid and that effectively means us) but~ surprisingly, the D2 is given as six weeks I was always under the impression that Dl had a fairlonger life than D2. Must be
something just a wee bit different in the 1~üji chemistry’
A section deals with +~he raising and lowering of the pH values of solution sing as we do 10% NaOH (raise) or H2S04 (to lower) the Dl and/or D2.
The manual has a most interesting section dealing with the effects on the final transparency caused by t1~e concentration or dilution variations of the various stages, temperature variations, agitation, pH values and most interestingly a large
selection on the contamination between variations of different solutions Dl with D2 : D2 with Dl Dl with reversal : in fact a whole series of the different combinations.And each of all the contaminations carries a series of colour illustrations showing what differences can be expected. Each series uses a ‘normal’ picture for instant comparison. Interesting, informative and valuable and I salute Fuji for ensuring that their films are treated as far as possible with the ultimate in processing technique.