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  #1  
Old 15th October 2016, 01:28 PM
John King John King is offline
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Default RA4 Developer oddity

I have just had a re-vamp of my darkroom and sorted out various stock of chemicals. I intended to do some RA4 printing later on tonight but had no ready mixed replenisher available.

I use Kodak Ektacolour 20Lt packs and I had just enough left in my current pack to make 1ltr. The quantities of concentrate to make 1 ltr are 50cc of 'A' 24cc of 'B' and 50cc of 'C'. These are all mixed in alphabetical order into 700cc of water around 24degrees 'c'. Stiring the liquid as they are mixed.

Concentrate 'A' is vitually colourless as is 'B' when they are mixed together in the water, but when you add 'C' the working soloution should turn a mid green, eventually clearing within a few seconds to a very light straw colour. Today it turned to a deep blue and didn't clear!

I did a 'dip' test with a piece of RA4 paper and the paper developed to give a decent black, I am wondering why the change of colour in mixing?

All the concentrates were normal, only the soloution 'A' discolours with time and this was still pale creamy clour. The jug used for mixing it was clean as were the smaller measuring beakers.

Any thoughts?

I am still going ahead with the printing tonight and will have to add some of todays mix before I start so what I get should be ......errrr..... interesting.

If it all goes belly up, I have no concentrate left and will have to buy a new kit so all's not lost.
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Old 15th October 2016, 03:13 PM
Mike O'Pray Mike O'Pray is offline
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Let us know what you find, John. As a glass half full person I suspect that the developer might be on its last legs, given what you have described but I hope I am wrong

Mike
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Old 16th October 2016, 10:19 AM
John King John King is offline
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Default A Theory

I have not processed any prints since the thread was opened - other events took over.

I have checked yesterdays new mix of RA4 working developer this morning and it has turned from blue to a dirty light brown with bits floating in it! They look like spiders web fragments.

Thinking about what might have happened before I made the new RA4, I had cleaned out the stop bath slot of the processor and rinsed the 2 litre jug, but probably not sufficiently so there was still Acetic Acid contamination. The jug which is probably 15-20 yr old isn't smooth inside and would have probably retained enough stop bath to contaminate the RA4 chemicals.

I remember the last time I processed E6, the Tetenal kit instructions contained a warning about cross contamination and advised that plastic measuring beakers should be marked with individual contents and only used with one chemical.

The processor is warming up as I type and will try a print or two when it is up to temp and see what happens. I am not that worried because I was due to order a new box of Ektacolour in any case.

I have sourced a supplier of laboratory glass measuring beakers at a reasonable price so the plastic ones can be replaced with ones that wash out easily. Actually the price they quote is less than I would expect to pay for proprietry photographic ones. (No surprise there)

Last edited by John King; 16th October 2016 at 10:24 AM.
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Old 16th October 2016, 01:41 PM
John King John King is offline
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As expected, the new mix has contaminated the developer slot in the Nova deep tank. Yes I managed to get an image - of sorts but it was lacking in colour, i.e monochrome and very faint.

It has given me a good excuse to empty the processor completely and give it a deep clean. I have refilled the stop and blix slots with new chemistry and just wait for the fresh RA4 concentrate to arrive. Ah well you learn something new almost every day.
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Old 18th October 2016, 09:38 PM
John King John King is offline
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The new Ektacolour arrived today and a fresh working solution made up using the new glass measures rather than the plastic and the colour reproduction is superb!

I had to do a few test prints to get it back on an even keel mainly by removing a shed load of magenta filtration - about 30 units then about 15 yellow as well. All's well again.
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Old 19th October 2016, 11:03 AM
Mike O'Pray Mike O'Pray is offline
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Good news, John. I winder if the "old" developer(assuming any is left) from it's presumably uncontaminated container but mixed in your new glass beakers would have been OK as well?

Mike
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Old 19th October 2016, 02:43 PM
John King John King is offline
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Nothing left Mike. I just dumped it when it was obviously 'shot'.

The benefit of the glass beakers and mesuring cylinders, is they are made from a glass similar to Pyrex, so they went into the dishwasher.
One thing I have learned from that experience is that from now on I am going to be meticulous where there may be a risk of cross contamination and not so cavalier about keeping the containers spotless. (you would think after all the time I have been processing colour that I would have done so already).
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Old 19th October 2016, 07:01 PM
Mike O'Pray Mike O'Pray is offline
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John, I hadn't realised that it was glass similar to Pyrex which presumably makes it much less likely to shatter if accidentally knocked over. My fear of glass has always been it breaking into a thousand almost invisible shards which makes cleaning up after an accident a nightmare.

If it is largely shatter proof in the way I described above then should my plastic beakers ever show signs of roughness on their surfaces then this stuff you've bought is even more attractive at the price

Mike
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Old 6th April 2018, 07:55 PM
JOReynolds JOReynolds is offline
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Quote:
Originally Posted by John King View Post
The benefit of the glass beakers and mesuring cylinders, is they are made from a glass similar to Pyrex, so they went into the dishwasher.
My friend in Idaho uses Pyrex for the pendulums of his clocks, which are very accurate (and works of art). Pyrex is a borosilicate glass and has a very low coefficient of expansion, which means that it can withstand being filled with ice and heated on a Bunsen burner - the differential expansion is very small, so there is little stress to fracture the glass.
I agree with keeping everything spotless. I used to run processing laboratories and once nearly got fired for suggesting that a member of my team should drink from a vessel to prove that it was as clean as he asserted.
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