myimproved HCAformula

[Ian Grant]

Agfa recommended 2% Sodium Carbonate solution as a wash-aid right up until they ceased production of B&W papers. It has two actions first as you say by raising the pH and swelling the emulsion slightly and also as a hypo clear by ion exchange albeit weaker than sulphite but because of the selling effective.

Plain Sodium Chloride works as well.

Ian

 

[Ian Grant]

You're right Michael all the Agfa papers I used have been well hardened so softening of the emulsion wasn't an issue.

Ian

 

[Rudeofus]

With today's neutral rapid fixers: can we still expect a benefit from alkaline wash bathes?

 

[Rafal Lukawiecki]

Agfa recommended 2% Sodium Carbonate solution as a wash-aid right up until they ceased production of B&W papers.

Actually, this recommendation is still part of the information leaflet included with Adox MCC 110. I must say, I have not followed it, though, preferring sulfite.

Then again I may be in over my head... I'll just keep using Ilford Washaid

This subject fascinates me, and both of you might remember my (there was a url link here which no longer exists) questioning why Ilford and a few other references indicated that the capacity of the fixing bath increases when sodium sulfite wash aid is used after fixing. I am still at the stage of experimentation, and the early results are promising but not statistically solid, yet. So far, I am seeing a minor improvement in "clearing" time of a paper treated to a bath of sodium sulfite compared to the same one that did not have that bath, following fixing in a neutral pH 12% ammonium thio fixer (similar to a 1+4 concentration) that contains 2g Ag/l (exhausted), as tested with sulfide. How big is the difference? Tiny: 5 seconds. But I am also seeing that with my test papers, MGWT FB, Fomabrom Variant 111 and ADOX MCC 110 the clearing times are all very short, even in an exhausted fixer, ranging between 7-15 sec. When I have more data, I will write up something more meaningful on my original thread, but I just wanted to drop this note to say that there seems to be more to sulfite HCA than has been written so far, and not just in helping desorb thio from fibres and the emulsion. On the other hand, I am also starting to question the need for a 2-bath regime, with these papers and fixers. But that'd be another thread...

 

[RalphLambrecht]

photographic research ma y be up to the APUG community now that the big three are not doing it any more; how exciting!

 

[RalphLambrecht]

Too late to edit my previous posts but need to make a few corrections in post #29.

Where I wrote "...the mechanism of the pH increase was to release the gelatin-alum complexes - which would take the adsorbed thiosulfates them".

It should have read: "...the mechanism of the pH increase was to release the Aluminum which would take the mordanted thiosulfates with it".

The recommended alkali treatment by Agfa was a 1% Sodium Carbonate bath. Looking at the Brovira leaflet (I don't know exactly what year it was from but probably the 70s) the instructions also indicated not to use the Carbonate bath if a hardening fixer had been used. So this all seems consistent with the mechanism described in Haist.

would a combination of sodium sulfite, sodium carbonate and sodium chloride make sense or just unnecessarilycomplicate things? just thinking because Agfa,Ilford and Kodak made different recommendations initially.

 

[Gerald C Koch]

would a combination of sodium sulfite, sodium carbonate and sodium chloride make sense or just unnecessarilycomplicate things? just thinking because Agfa,Ilford and Kodak made different recommendations initially.

The particular chemical used seems not to make that much difference in wash rates. Sodium sulfite seems to be a bit better than the others followed by sodium carbonate and then sodium chloride. There would be no real advantage in using a combination of them. One should test the use of sodium carbonate with your particular paper as the alkalinity could soften certain emulsions.

 

[Rudeofus]

On the other hand, current materials are well hardened during manufacture.

I use a combination of Sulfite and Carbonate as prewash. My main issue is that hard water turns that mix into a milky soup which only clears if I add enough Citric Acid to turn the combo almost neutral (pH ~ 8). Note that Citric Acid not only brings pH down, it also acts as mild chelating agent for Ca++ and Mg++. Even before I lowered pH with Citric Acid I never had any issues with photographic papers. Most paper developers have pH > 10, and hardening fixers have become very uncommon by now, so an alkaline prewash should not really cause trouble.

@Rafal: could you provide us with a brief explanation how you measure clearing time of photographic paper, especially with the time resolution you need for your tests?

 

[Gerald C Koch]

Rudeolfus makes an good observation that a sodium carbonate solution using hard water may leave a scum of calcium carbonate on prints.

 

[Ian Grant]

Rudeolfus makes an good observation that a sodium carbonate solution using hard water may leave a scum of calcium carbonate on prints.

Actually you can get a slight scum on prints with a plain Sodium Sulphite hypo clearing bath in hard water areas, that's why Kodak used EDTA (Tetra sodium) in their HCA.

My preference is to use a plain 2% Sodium Sulphite solution. The reason for the additions of Metabisulphie, Citrate etc in Kodak HCA is pH stability in a solution which is stored, and often reused.

Ian

 

[RalphLambrecht]

Actually you can get a slight scum on prints with a plain Sodium Sulphite hypo clearing bath in hard water areas, that's why Kodak used EDTA (Tetra sodium) in their HCA.

My preference is to use a plain 2% Sodium Sulphite solution. The reason for the additions of Metabisulphie, Citrate etc in Kodak HCA is pH stability in a solution which is stored, and often reused.

Ian

I had the same problem but as Ian says, after adding 1gof photo calgon/l the scum was gone.

 

[Rafal Lukawiecki]

@Rafal: could you provide us with a brief explanation how you measure clearing time of photographic paper, especially with the time resolution you need for your tests?

Rudi, I have used the approach suggested by Ralph in WBM. Bear in mind, I wrote "clearing" in quotes, as the test does not really look for clearing, as such, but purely at a level of residual silver halides. In essence, you make a test strip that you progressively immerse in the (spent in my case) fixer at 5 s intervals, previously marked off on the back with a pencil. After any additional processing (HCA+wash vs wash alone), the strip is subjected to a sulfide toner, and the first strip behind the one that shows a hint of density/tone difference is read as representing the "clearing" time. WBM describes it better than I did, and with pictures. By the way, I also did a variant of this test, going from the neutral fix straight to Se tone, without a wash, and that showed the same results, within 5 s tolerance. However, having only run 6 of those in two batches, I just don't have enough data to see what measurement error there may be, notwithstanding plenty of opportunity for other conceptual faults of this method. I'll keep on testing using different batches of the 2g Ag/l fixer.

 

[john_s]

Actually you can get a slight scum on prints with a plain Sodium Sulphite hypo clearing bath in hard water areas, that's why Kodak used EDTA (Tetra sodium) in their HCA.

My preference is to use a plain 2% Sodium Sulphite solution. The reason for the additions of Metabisulphie, Citrate etc in Kodak HCA is pH stability in a solution which is stored, and often reused.

Ian

I think that i read somewhere that the metabisulphite is there to adjust the pH in order to optimize some characteristic of the gelatin to maximize clearing. I'll try to find the reference.

 

[Hal Reiser]

After reading this thread I have decided to start mixing my own HCA using Gerald's formula. My schedule these days does not allow for much darkroom time on a regular basis and mixing from powder as I need it makes much more sense to me. Also I've also finally gotten tired of throwing out commercially made products that have gone bad due to lack of use over time.

I do have a question regarding times for this formula.

In my current workflow I hold the finished prints soaking in a large tub of water. The water is changed several times during the entire session. When done printing I first wash the prints for 5 minutes. The prints are then soaked for 5 minutes in my present wash aid and then final washed for 10 minutes. This workflow is based on the times provided by the manufacturer of my current wash aid.

Would this system be acceptable using the 2% sulfite formula or would I need to increase my times?

 

[Rafal Lukawiecki]

Hal, what is the paper that you use, and what is your fixing and toning procedure? The answer to your question greatly depends on those aspects, but I suspect your procedure may be ok for non-archival needs, and borderline for archival. Tell us more and I'm sure you'll get a better opinion.

Best of all, do the simple HT-2 test (and while at it, the ST-1).

 

[RalphLambrecht]

I had the same problem but as Ian says, after adding 1gof photo calgon/l the scum was gone.

same here, but ,Iwasn't aware that Kodak used citric acid in HCA.How much?:confused:

 

[RalphLambrecht]

After reading this thread I have decided to start mixing my own HCA using Gerald's formula. My schedule these days does not allow for much darkroom time on a regular basis and mixing from powder as I need it makes much more sense to me. Also I've also finally gotten tired of throwing out commercially made products that have gone bad due to lack of use over time.

I do have a question regarding times for this formula.

In my current workflow I hold the finished prints soaking in a large tub of water. The water is changed several times during the entire session. When done printing I first wash the prints for 5 minutes. The prints are then soaked for 5 minutes in my present wash aid and then final washed for 10 minutes. This workflow is based on the times provided by the manufacturer of my current wash aid.

Would this system be acceptable using the 2% sulfite formula or would I need to increase my times?

I believe you'll be OK with your workflow, but as someone already suggested, do a residual hypo test. in a pinch you can also use toner for it.