Kodak Ektacolor RA4 RT/LU staining
Here in the land of weird RA4 printing disasters, I am having difficulty with Kodak Ektacolor RA4 RT/LU chemistry in a Nova vertical slot processor. I'm using 1 minute develop and bleach/fix times at 33C with Fuji Crystal Archive paper and have tried with and without an Ilfostop citric acid indicator stop bath. I've used Tetenal and Fuji Hunt chems before, typically with good results, so I have got some experience of colour printing.
In all of the following cases, the staining/colour cast occurs on the print and the borders. Initially, the prints looked as though the base colour of the paper hadn't been removed - the prints had such a strong cyan cast that they looked like an inkjet print on the undeveloped paper (if you see what I mean). This cleared with later prints but there was still cyan staining particularly on the bottom edge of the paper (they are developed vertically in the slot processor). Then I went through a phase of getting prints that looked quite good in the top half but with faint cyan staining on the bottom half, increasing with strength towards the bottom of the sheet. Now I have prints that have a pale green cast all over and look rather thin - the sort of thing one would expect from under-exposure or under-development. But rather extraordinarily, I did get one print with pure white borders that looked perfect. I've done about 40 10x8 sheets in total.
Does anyone have any idea what is causing this, or what I should try next? I guess the obvious thing is just to mix up some more, but I don't want to make the same mistake twice. Can the chemicals have gone off already - bought about a month ago? Were they bad to start with? Didn't I mix them properly? I'm running out of ideas.
Thanks for any help or advice.
Last edited by Edward_S; 10-24-2013 at 12:39 PM. Click to view previous post history.
Are you replenishing after every few sheets? At least 10ml per 10x8" RA4 sheet, pro-rata for larger paper. Don't forget that the blix also needs replenishment.
Did you mix the chemicals in the slots, and therefore possibly not mixed them perfectly?
Was the paper more than two years old, or not stored in a fridge?
Are you trying to use a safelight? (Probably not a good plan).
Are there any new electrical devices in the darkroom with, for example, indicator lights that were previously not present?
Assuming that you were using the tubular lids for each tank, did you also seal the unit with clingfilm over the top after each session?
No, I'm not replenishing. Is this what you do? Advice seems to differ on this in various APUG threads. It's confusing! I should also say that I haven't used any starter, but this doesn't seem to be essential as far as I can tell.
I mixed 5L in one go in large plastic containers, but in my excitement to get started I probably didn't use warm enough water, or stir for as long as suggested between each addition of the various parts. Is this an irreversible error? Or does it mix once up to temperature in the slots? It's had about a month to mix in the slots since I made it!
It's new paper (well, new from the supplier, anyway) and I'm not using any safelights of any sort
I have a large plastic tray that fits snugly over the top of the tank when the tubes are in; that seems to be reasonably airtight. I note that at least one person on APUG has stated that the mixed stuff lasts for weeks.
But... there is obviously something wrong in my case. Thank you for your suggestions. Could it be a problem with initial mixing?
Citric acid stop is not recommended with color papers. Try acetic acid based one, or just use a plain water wash between dev and blix.
P.S. Sorry, just noticed that you did try without the stop. In that case, fogging is the more likely culprit.
All else being equal, the longevity of the chemicals in a slot processor does pretty much depend on replenishment, yes. With black and white processing one can instead extend the time in the developer and fix, to some extent at least, but with RA4 the results would be more sensitive. Do you still see a problem if you set the thermostat to give 35C (insulate the processor with bubble-wrap if necessary), adjusting the times to suit, and/or extend the blix time?
With a suitable long stirring implement you can give the chemicals a good mix, but if they were originally done in a bucket and not in the slots then it shouldn't be needed. That is so long as the water was not 'cold' - Kodak quote 21-38C for mixing.
The instructions for the unit cover B+W and RA4 replenishment rates. How critical that might be, regarding noticing differences between the sessions, may also depend on how large the processor is as a 20x16" unit obviously has much larger volumes than the 10x8" version - but the replenishment rate is the same. They do give a longer total usable lifespan for the larger tanks so replenishment has some limits eventually. Try Googling for a PDF of the instructions of your particular model, or contact Nova for the PDF. The instructions for my (third-hand) processor disappeared before I ever bought it and I didn't make a note of the download address I used for the file.
Last edited by MartinP; 10-24-2013 at 02:22 PM. Click to view previous post history.
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Maybe the blue coat of the paper isn't getting sufficiently rinsed off. Standardizing on one-minutes times seems awfully short to me. There are
also the replenishment and/or lack of agitation issues already mentioned.
A question for Drew Apart from exhausted and aged chemicals, isn't another possible cause of blue-ish, or cyan, highlights/borders when there has been some blix in the developer? That might be involved in the OP's problem, and fixed by replacing the developer and washing out the slot before refilling.
Back contamination with fix or blix can cause this as can poor stopping. Another typical causes is red safelight fog.
Yeah Martin, blix contamination is an inherent risk of slot processors, where all the different chem are in such close proximity. These kind of hypothetical issues just have to be isolated one at a time, until the problem disappears.
That happened to me in a nova until I placed a non-citric stop bath, also use the blades as per instructions to wipe the back of the print to minimize any carriover.