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Old 27th March 2020, 08:58 PM
Nat Polton Nat Polton is online now
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Default Stop Bath for Tetenal RA-4

I have just received a parcel of chemicals and paper to alleviate lockdown boredom.
One item I have is the Tetenal Colortec RA-4 Kit.
I have not printed colour since 1992, and I am going to get reacquainted with colour work over the next couple of weeks.
One thing not supplied is a stop bath. Tetenal recommend Indicet Stop Bath.
I have read someplace in the past that acetic acid will work as a stop bath for RA-4 processing.
Is this true? And if so, does any body know the correct dilution to use?
I already have some acetic acid available, and do not fancy having to pay postage on one bottle of Tetenal Indicet.

Cheers all.
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Old 27th March 2020, 09:14 PM
Mike O'Pray Mike O'Pray is offline
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Nat do not take this as gospel until there is confirmation from others but I am pretty sure that an ex Kodak colour film and paper engineer said that acetic acid was the one to use for RA4 as opposed to citric acid so yes it is the right stuff and its dilution is whatever the maker's bottle says. For paper that dilution usually is 2%

Mike
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Old 28th March 2020, 08:24 AM
Lostlabours Lostlabours is online now
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I use 2% acetic acid in my Nova deep tanks when processing RA-4. A stop bath is necessary because of carry over.

Commercial processing machines rarely use a stop bath as the roller transports squeegees the excess developer off the front and back of the paper. It's the same with films B&W and Colour roller transport film processors generally don't have a stop bath.

Ian
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Old 28th March 2020, 08:44 AM
Nat Polton Nat Polton is online now
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https://www.firstcall-photographic.c...df/pdf6870.pdf

Just found a pdf instruction sheet for Adox RA-4 Professional Kit on the Firstcall Website advert.

It looks like you are both correct.
Many Thanks to you both. You have saved me a few quid on the carrier charges for one bottle of stop bath.

……………….see page 6.
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Old 28th March 2020, 11:51 AM
John King John King is offline
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Default Stop bath

Yes it should be an acetic acid version for the stop bath.

Any of the commercially available ones will work when diluted to the working solution suggested on the bottle. I use the Kodak high concentration type (Dilute 1 to 63) (It is cheaper in the long run and I am mean)

The citric acid type has the unfortunate habit of growing a fungus on the surface of the chemical when left for more than 2-3 days which if transferred to the paper surface will be next to impossible to remove.
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Old 28th March 2020, 03:03 PM
Nat Polton Nat Polton is online now
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That is very interesting John.
I just looked up the safety data sheet for Tetenal Indicet, the stop bath Tetenal recommend.
Indicet is citric acid. Possibly it is the only stop bath they make, so that that is why they suggest it.
https://www.digitaltruth.com/product...dicet-MSDS.pdf
The link above goes to the safety data sheet. Section 3 mentions the citric acid.
All of my colour developing in the nineties was done in a Paterson Thermodrum using one shot chemistry. So the problem of mould never arose... I now have a second hand Nova four slot tank. So mould would probably appear with the Tetenal Indicet Stop Bath.
Definitely going to be acetic acid for the stop bath.
Cheers.
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Old 28th March 2020, 03:34 PM
John King John King is offline
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Quote:
Originally Posted by Nat Polton View Post
That is very interesting John.
I now have a second hand Nova four slot tank. So mould would probably appear with the Tetenal Indicet Stop Bath.
Definitely going to be acetic acid for the stop bath.
Cheers.
The NOVA tanks are where it appeared with me. The first and last time I used it.

When you shut down for the night, the chemicals are still warm and that propagates the formation of mould. It is like a dark grey fur coat and if you put an already wet sheet of printing paper into the slot the miniscule mould fibres will stick to it and degrade the image. Once the print is dry you will never get rid of the fibres, and if you try when it is wet you may damage the surface of the print.

When I started colour printing around 1991/2 that is all we had.

If you have never used a NOVA before, a tip that I have used almost from day 1, was after you have topped up the chemical slots (replenish each with 10cc for every 80sq ins of paper) cover the top of the processor with cling film. It will slow down the deterioration of the colour developer, but also and more importantly it will stop evaporation of the water in each chemical slot so it can be left for several weeks if need be with little deterioration.
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