slowing down HC-110 development

[Rudeofus]

Fomapan developed in 1:16 HC-110 would turn out black because that dilution is too active for this film. That's why I reduced the activity by adding acid, and 1:16 was required in order to get the recommended minimum 6 mL of developer per roll of film, given the volume of the tank in my processor.

I realize that HC-110 without acid would be a lot more active, but are you sure that even unexposed parts would be totally black? Also, you tried to use HC-110 1:16+acid instead of HC-110 1:64, so you could still run a meaningful comparison between these two. While it is trivial to slow down a developer with acid, you really want to make sure that you don't lose two stops of speed in the process.

 

[koraks]

Since fomapan 100 struggles to attain 100 even on a good day, odds are he lost less than a stop.

 

[alanrockwood]

Although I did not try this with HC-110, I have always used baking soda to slow development. It is not drastic like vinegar and seems to allow for great tonality. You will have to experiment, but I would try about 5ml in your 300ml working solution. Try a clip test first: Why waste a full roll? - David Lyga

Baking soda is an interesting idea.

For my experiments I did a clip test first to narrow the amount of vinegar down to a level that would give a development speed roughly comparable to 1:64 HC-110. A clip test would also be a good idea if I decide to try baking soda.

 

[Rudeofus]

The good thing about vinegar is that it has no photographic effect other than lowering pH. Baking soda lowers pH, but also increases buffer strength.

 

[alanrockwood]

A curve of Fomapan developed normally for it then would be of use. This curve does not tell me much.

PE

The curve I posted told me what I needed to know, which is what time of development would give me a reasonable characteristic curve for the new mixture I was interested in evaluating.

However, before doing that run I also did several other experiments. One was a clip test to see how much vinegar would give a development velocity roughly comparable to 1:64 HC-110, and a 1:16 HC-110 diluted into 0.625% acetic acid developed the clips almost as fast as the 1:64. This was evaluated by eye as the clips developed under regular room light, so it was only a very rough test to get a starting point.

Before I generated the characteristic curve for the new developer run at 6 minutes, I did three other runs. One in 1:64 HC-110 developed for 3 minutes using a series of exposures of a blank wall, one in the new mixture (1:16 in 0.625% acetic acid) developed for 3 minutes, and one in the new mixture developed for 4.5 minutes. I didn't plot those results because I wanted to avoid too much information-clutter. However, I now show them here.

As expected, the new mixture was roughly equivalent (but slightly less) in activity compared to the HC-110 1:64 mixture. If I ran the development a little longer it was slightly more active. Interpolating between those to curves to predict how the HC-110 1:64 developed for 3 minutes would compare to the new developer run at 3.75 minutes the overlap was virtually perfect, except for possibly a little more shoulder at high exposure using the new mixture. Here's a plot showing this.

(Note, this is a predicted result for the new developer mixture based on interpolating the results at 3 minutes at 4.5 minutes, not an actual experimental measurement.) The amount of development is a little too low, so I estimated that to get the desired level of development I wanted would probably take somewhere between 6 and 9 minutes. I did a run at 6 minutes and got the curve below (which is the same one I plotted earlier).

As noted in my other post, this might be slightly overdeveloped, but I figure it is good enough for my purposes, although it might be worth dropping the development time just a bit to tame the contrast a little.

Anyway, that's the process I went through to get to this result. For my purposes I don't need to try to match this curve to a curve using 1:64 HC-110 run at a longer development time because I won't be using the 1:64 mixture. To use the 1:64 mixture I could only run a single roll in my largest (4 roll) tank due to the minimum 6mL per roll recommended minimum HC-110 volume, but with the new mixture I can run 4 rolls in my 4 roll tank and still stay within 6mL/roll of HC-110 concentrate.

 

[alanrockwood]

Thinking more about the baking soda idea, I think maybe the two pKa values for the carbonic acid/bicarbonate/carbonate system (6.1 and 10.3) are spread too far on either side of the pH range of the developer, so adding bicarbonate would not be very effective in changing the pH. The bicarb would end up being more of a spectator ion than participating in the acid/base balance. I haven't worked out the detailed math on this, so I could be wrong.

By the way, I don't know what the pH of the new developer mixture is, though I would guess it is probably somewhere in the neighborhood of pH 8.

 

[alanrockwood]

I realize that HC-110 without acid would be a lot more active, but are you sure that even unexposed parts would be totally black? Also, you tried to use HC-110 1:16+acid instead of HC-110 1:64, so you could still run a meaningful comparison between these two. While it is trivial to slow down a developer with acid, you really want to make sure that you don't lose two stops of speed in the process.

Yes, I think you are right. It might not be totally black, but HC-110 at 1:16 without acid would overdevelop fomapan 100 so severely that it would not be worth doing. As noted in my second-to-most recent post, I did do some HC-110 1:64 comparisons to the new mixture, though it was at a shorter development time. I posted the characteristic curves.

 

[Rudeofus]

Yes, I think you are right. It might not be totally black, but HC-110 at 1:16 without acid would overdevelop fomapan 100 so severely that it would not be worth doing. As noted in my second-to-most recent post, I did do some HC-110 1:64 comparisons to the new mixture, though it was at a shorter development time. I posted the characteristic curves.

Yes, the new curves you posted show a great match between 1:16+acid vs. 1:64 with times correctly adjusted, so I guess you found what you were looking for.

A final thing I still don't quite understand is graph 1 vs. graph 3 in your posting. In graph 1 you compare HC-110 1:16+acid with development times at 3 and 4.5 minutes against HC-110 1:64, with no temperature specified in this graph. In graph 3 you developed for 6 minutes at 23.9°C and got somewhat more contrast. Was graph 1 taken at the same temperatures? If 3 3/4 minutes is normal development, then 6 minutes should be a massive push ... am I reading this correctly?

 

[Photo Engineer]

Good data. Thanks.

PE

 

[alanrockwood]

Yes, the new curves you posted show a great match between 1:16+acid vs. 1:64 with times correctly adjusted, so I guess you found what you were looking for.

A final thing I still don't quite understand is graph 1 vs. graph 3 in your posting. In graph 1 you compare HC-110 1:16+acid with development times at 3 and 4.5 minutes against HC-110 1:64, with no temperature specified in this graph. In graph 3 you developed for 6 minutes at 23.9°C and got somewhat more contrast. Was graph 1 taken at the same temperatures? If 3 3/4 minutes is normal development, then 6 minutes should be a massive push ... am I reading this correctly?

All development was done at the same temperature. The results at around 3 minutes are under developed. The result at 6 minutes is closer to normal development, though it might be slightly overdeveloped. (The results at 6 minutes are actually pretty close to the slope specified by iso for determining film speed, which is 0.62 vs. ~0.65 in these results, although some people consider the iso conditions to correspond to over development.)

 

[Raghu Kuvempunagar]

When I brewed Gerry's Kalogen last time, I didn't have Metol powder with me. So I ended up using water based (5% Metol, 1% Metabisulphite) solution that I had prepared for other purposes. As I didn't use additional Sodium Hydroxide to neutralise Metabisulphite, pH of Kalogen went down and consequently the time for development also increased. Negatives turned out to be fine though.

 

[David Lyga]

The good thing about vinegar is that it has no photographic effect other than lowering pH. Baking soda lowers pH, but also increases buffer strength.

This is, perhaps, the ADVANTAGE of using baking soda. Vinegar is too 'all or nothing' to suit me. I like the buffer idea. - David Lyga

 

[David Lyga]

David, baking soda is a solid. So, what is 5 ml???

PE

I measure powders with volume, PE. Actually, maybe only ONE mL per 300 mL would be better, as the stuff is powerful!!!! - David Lyga

 

[Rudeofus]

This is, perhaps, the ADVANTAGE of using baking soda. Vinegar is too 'all or nothing' to suit me. I like the buffer idea. - David Lyga

The buffering in HC-110 is already provided through the Triethanolamine contained therein - with baking soda you'd add a second unrelated buffer system to the mix.

 

[Photo Engineer]

David, what kind of baking soda? Crystals, powder, what? Each of these occupies a different volume by weight. This is a very precarious method to measure things.

PE

 

[David Lyga]

David, what kind of baking soda? Crystals, powder, what? Each of these occupies a different volume by weight. This is a very precarious method to measure things.

PE

Simply the one bought in a grocery store. The Sav-A Lot chain has a pound package for only 59 cents. That satisfies even the frugal David Lyga. There is something about putting this into developers. I am not a chemist and maybe this is simply fantasy, but it seems to impart a sort of smoothness and consistency to the formula. Maybe the 'buffer' aspect is why, I do not know, but vinegar is far too drastic and unpredictible for me to attempt.

PE, honestly, I never have problems with consistency and, to tell the truth, I would rather this, than reuse developers. - David Lyga

 

[Photo Engineer]

Using liquid measure for a solid is a dangerous practice David due to the variability.

There are several threads on this here.

PE

 

[David Lyga]

But, are there not cases whereby a solid can gain weight (for example, sodium sulfite, crystal) by absorbing air? Honestly, I have never had problems measuring my metol, HQ and sodium sulfite, anhy in this way. I use more accurate measuring cylinders than 'spoon' measurement which some use. You are entitled to impart differently, but I am satisfied with my results. Of course, you are the one with the most experience, Ron. - David Lyga

 

[Photo Engineer]

If they gain air, the volume per unit weight goes up. Using a spoon, I would say "what kind"? I asked my wife for 2 tablespoons the other day, and she grabbed two from two different sets we have in the kitchen. They were different shapes and sizes.

It is always best to use weight. There was a segment on TV tonight about the dangers of using volume to measure flour in baking. There is a 20% variation in volume depending on type of flour and season (weather).

PE

 

[Raghu Kuvempunagar]

I haven't tried evaluating other factors, such as grain or sharpness.

Please do consider reporting your observations on these factors when you get time. Will be very valuable.

 

[Rudeofus]

Several decades ago scientific researchers investigated all kinds of different developing agents and formulas, and came to the conclusion, that the strongest determining factor regarding the speed/grain/sharpness triangle is speed of development. Allow a developer to work for 10+ minutes and results will likely be better than those of a developer which develops to normal contrast in 5 minutes. Therefore it's quite likely, that Alan's modified HC-110 works better than the original formula. Emulsion speed is comparable according to his charts, therefore we can expect some combination of finer grain and higher sharpness.

 

[baachitraka]

If I understand it correctly, his target is to achieve the same thing at 23.9 deg C. Its nice to see the curves match.

 

[Raghu Kuvempunagar]

Several decades ago scientific researchers investigated all kinds of different developing agents and formulas, and came to the conclusion, that the strongest determining factor regarding the speed/grain/sharpness triangle is speed of development. Allow a developer to work for 10+ minutes and results will likely be better than those of a developer which develops to normal contrast in 5 minutes. Therefore it's quite likely, that Alan's modified HC-110 works better than the original formula. Emulsion speed is comparable according to his charts, therefore we can expect some combination of finer grain and higher sharpness.

Rudy, when a developer contains multiple reducers which are active differently at different pH, wouldn't lowering the pH, as in this case, mean that the relative activity of individual reducers is going to be different at the lower pH and hence grain, sharpness, microcontrast, smoothness, etc can be substantially different? Forgive me if I'm asking a question for which the answer is trivial and I don't know that answer.

 

[Rudeofus]

This may be true, but there are only few developer formulas out there with competing development agents, and HC-110 is not one of them. AFAIK HC-110 uses Dimezone-S and Hydroquinone, these are superadditive but not competing.

 

[Anon Ymous]

This may be true, but there are only few developer formulas out there with competing development agents, and HC-110 is not one of them. AFAIK HC-110 uses Dimezone-S and Hydroquinone, these are superadditive but not competing.

Surprisingly, HC110 also contains Catechol, which I assume doesn't differ very much from Hydroquinone in that respect, if at all. I'd really like to know the reason for the inclusion of Catechol in this developer.