Let's consider another proposition. In the face of so much buffering, will it really make a difference if you use ascorbic acid instead of sodium ascorbate? If not, then the TEA can be left out and a B solution of 1 gram of phenidone and 12 grams of ascorbic acid in glycol or glycerol used. As I review what I've been preaching, I see that 12 grams of ascorbic may not dissolve in 100 ml of glycol. If not, use 200 ml and double the dose to 20 ml/l of working A.
Pat, the buffer seems pretty weak. There's potassium carbonate and then a small amount of the bicarbonate, of sodium sulfite and sodium metabisulfite. I'd worry about shifting the pH around using straight ascorbic acid.
The formula looks interesting but I'd want to see noticeably better image qualities to deal with all these reagents (rather than mixing up PC-Glycol or something comparable).
From the book: Controls in Black and White Photography by Dr. Richard J. Henry. 2nd ed.,Focal press, 1986...
"I want to digress a moment here to discuss the method of notating dilutions. Many authors in photography employ the form 1:2 when thy mean 1 part of the solution to be diluted added to 2 parts of the diluent, usually water. In most other scientific fields the notation 1:2 has an entirely different meaning, namely, "dilute 1 part of the solution to be diluted to a final dilution of 2 parts thus, equal parts of each or 1+1. To avoid confusion, therefore, throughout this book I will use the notation 1+1, 1+2, 1+3, etc so that there cannot be any chance of confusion as to what is meant." page 88.
This book, now out of print (unfortunately), should be on the bookshelf of every serious black & white photographer. Henry used the Scientific Method to confirm or de-bunk some of the endless flood of words and opinions published over the years. Too bad he isn't around today to continue his investigative work.
Reinhold
www.classicBWphoto.com
Thus, 1:1 really should mean 1 part mixed with 1 part to produce 1 part? In mathematical logic, IIRC, the colon indicates a ratio, not a sum. Alone, it does not specify the final quantity, but only the ratio between its parts.
Keith It's the latest issue. You raise some good points. Part A makes 1 ltr stock to which part B is added. However my tank only needs 250ml at a 1:9 dilution. So do I add the same quantities, as Mr Crawley suggests to 1 litre, to 250mls. My assumption was that I do as I assume that part B remains the same whether you use the whole litre or only a part of a litre. In effect it is part B to say 25mls of stock at 1:9 to make up my 250 mls
However an assumption is all that it is. If part B was proportional to liquid used then I think that Mr Crawley would have mentioned it. In fact at a further dilution of part A at 1:9 the phenidone quantity would drop to a very small level - impossible to measure by most normal scales.
So until someone who knows better tells me, I'll continue to assume that part B is a fixed amount to be added each time to whatever portion of the 1 litre needed at a 1:9 dilution to make up a sufficient developer quantity
pentaxuser
.....We in the UK have been unable to use TEA as it has not been available,....
Peter
PU (and others!)
I had a quick look at the article again this morning and Part A is made up to the 1000ml mark as per my original post. This solution is then diluted for actual use, with the example given of 30ml of Part A diluted to 300ml with water, i.e. the quantity required to dev a 35mm film in a Paterson tank. The part B chemicals are added to this dilute mixture with the info that the ascorbate will dissolve straight away, but the phenidone will take a few minutes plus some agitation.
Peter
Snip
I think that 10 ml of a B solution comprised of 12 grams ascorbic acid and 1 gram phenidone in 100 ml glycol or glycerol will use up 0.6 grams of sodium bicarbonate in becoming 1.3 g sodium ascorbate and 0.1 grams of phenidone plus carbonic acid, which acid becomes water and CO2. If you measure out the B solution first and add a small amount of the diluted A, you should observe effervescence. When that subsides, you may add the rest of the diluted A solution. Sodium ascorbate in water has a pH of about 7.6.
The difference between this solution and Crawley's will be 0.6 grams of sodium bicarbonate. Increasing the amount of the bicarbonate in the A stock solution by 6 grams should take out the difference without using TEA as the solvent in B. It should not affect the longevity of A. Alternatively, one could increase the amount of sodium carbonate in the A stock by 3.6 g (anh) . Either way, a small amount of diluted A should be mixed with the required amount of B and the effervescence allowed to subside before adding the remainder of the diluted A.
snip
Patrick, he calls for potassium carbonate not sodium, which is why I asked if anyone had measued the pH (v.s.)
I have none myself or I would have done it. All in all it looks like a complicated way to make PC-Borax. No? Well, maybe add a little sulfite for whatever it might do.
Murray
I'm guessing that FX-55 is a close variant of Paterson's FX-50 which was formulated by Geoffrey Crawley. But in spite of its eco credentials and alleged qualities, it attracted unfavourable comment because of perceived lack of keeping quality and sudden death syndrome. After Paterson were forced to find a new manufacturer for their chemicals, they re-introduced Aculux (as Aculux 3) and FX-39, but not FX-50 (or Acutol). Although there have been rumours about a second coming for FX-50 in an improved version, I am guessing that Geoffrey Crawley has decided to release this formula now because that is not going to happen.
It would be helpful to know how close FX-55 is to FX-50. For example, Crawley advocated an EI of 200 for Acros for standard development in FX-50.
JA.
Paterson Photographic Ltd would be wise to consider some of your suggestions Patrick as it might lead to FX-50 being reintroduced with a significantly increased shelf life.In case it's too difficult to figure out, here's a formula for a liquid FX55 part B with very long shelf life.
1 gram phenidone
10 grams TEA (it's liquid, but easier to measure by weight in such small amounts.)
12 grams ascorbic acid, either L- or D-
Glycol or glycerol to make 100 ml.
Glycerol is more viscous.
Use 10 ml of the above in place of 0.1 grams phenidone and 1.3 grams of sodium ascorbate.
If this is true, Kodak could extend the working life of Xtol by adding a chelating agent but they have not.The problem with FX-50 was Fenton oxidation of the ascorbate ion. Under the right conditions the Fenton reaction can destroy all of the ascorbate ion in a matter of hours. Paterson tried to remedy the short shelf life of the developer concentrates by separating the developing agents from the alkalies. Unfortunately tis will not work. Any ascorbate based developer needs a chelating agent to complex any iron (III) and copper (II) ions present in all the chemicals used in the making of the developer concentrates(s). This also includes the water used. Look at the formula at this site for further information. The salicylic acid chelates the iron and the triethalamine chelates the copper. http://www.digitaltruth.com/data/ds-10.php
Iron and copper are common contaminants of many chemicals such as sodium sulfite and sodium carbonate. The only way around the problem without using chelating agents is to add the ascorbate just before the working solution is used to develop film. Unlike the usual oxidation most people are familiar with Fenton oxidation will cause no color change in the solution. So there will be no warning that the developer has spoiled until it does not work. Paterson never realized what the real problem was and was therefore unable to solve the problem. They finally removed FX-50 from the market.
If this is true, Kodak could extend the working life of Xtol by adding a chelating agent but they have not.
The shelf life of Xtol in part full bottles is at least 2 months:
http://www.kodak.com/global/en/professional/support/techPubs/j109/j109.pdf
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