What EXACTLY are the benefits of 1:100 Rodinal?

dcsang

dcsang

Canadian & Not A Dentist
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Ok.. before I go wandering into the darkroom (aka my bathroom that has no windows), what exactly is the benefit of going to 1:100 dilution with rodinal when working with APX 100 (aka Silvertone 100)?

I usually opt for 1:25 because, well, it's FASTER to do - 1:100 takes 20 minutes... TWENTY MINUTES.

Anyway, can anyone tell me (other than wanting to save Rodinal concentrate) why one would go 1:100 versus 1:50 or 1:25?

Thanks,
Dave
 
The absolute benefits of using Rodinal 1:100 are longer development times and more rolls developed per bottle.

I use Rodinal 1:100 because I rate my films at half their box speeds and I like the results. My observations are good compensation in the highlights and good shadow detail from the extra exposure. Can't say much about grain, I've tried 1:50 a few times but not enough to gain much experience working at that dilution. I would say the grain was a little coarser. I also tended to get lower contrast using 1:100 but I feel that was more a factor of development time. I like longer development times so I can have more control and leeway during development.
 
Rodinal has sulfite in it. People think it has none, but it has metabisulfite and hydroxide. At the very alkaline pH all that hydroxide creates, the metabisulfite reduced to sulfite. A litre of 1:25 strength Rodinal has about 14g of Potassium Sulfite in it. This provides about as many sulfite ions as 10 grams of Sodium Sulfite. Although this is a fifth as much sulfite as a litre of D76 1+1 or half as much as a litre of Xtol 1+3, results change (and some would argue they benefit) with further dilution.

It's easier to control the grain in Rodinal developed negatives if you have more time to manage agitation - gentler agitation generally produces finer grain with Rodinal. That said, the tones you can get with Rodinal 1+25 and 1+50 are astounding for certain uses: just look at le vrai rdu's gallery to see what Rodinal 1+25 does with HP5+. Rodinal 1+50 produces beautiful tones on Tri-X and amazing, dark, golfball grain photos from TMZ.

Adjust to taste, as cookbooks say.

Marty
 
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Freakscene said:
Rodinal has sulfite in it. People think it has none, but it has metabisulfite and hydroxide. At the very alkaline pH all that hydroxide creates, the metabisulfite reduced to sulfite. A litre of 1:25 strength Rodinal has about 14g of Potassium Sulfite
in it. This provides about as many sulfite ions as 10 grams of Sodium
Sulfite. Although this is a fifth as much sulfite as a litre of D76 1+1 or half as much as a litre of Xtol 1+3, results change (and some would argue they benefit) with further dilution.

Marty
Click to expand...

Ahhhh.. this I can understand (not that Chris and Darren's explanations weren't also intriguing) - that said, I opted for 1:50 - this is still my "original" bottle of Rodinal - I still have two unopened ones I bought in, umm, 2007 ? ? *LOL* - It seems to hold up For-Ev-Er :D

Thanks for that explanation Marty.

Cheers,
Dave
 
Some people use 1+100 to enhance acutance with long developing times: stand and semi-stand development. I tried it, and didn't find any noticeable difference in relation to my usual 1+50. I guess with 1+25 you can have bigger grain.

I develop APX100 in Rodinal 1+50 years ago:

For overcast or in the shadows I meter incident at ISO100 and develop at 18ºC for 20 minutes with 30 seconds of initial inversions and then three inversions every minute.

Under direct sun I use a yellow filter and meter incident at ISO12 and develop at 18ºC for 12 minutes with 30 seconds of initial inversions and then three inversions every minute.

Prints are incredibly clean...

Cheers,

Juan
 
There's a real advantage for me in using Rodinal at 1+100 for large format.

I have one of those Combi Plan developing tanks that leaks like a sieve during inversions, uses a liter of developer to do six negs and is incredibly slow to drain and fill!

Stretching the processing time out by using 1+100 keeps the developing more even on the neg in spite of the very slow fill and drain times and minimises costs with only 10ml of Rodinal being used each time.

I also like the look of most films better at this dilution than 1+50 or 1+25. I have used up to 1+300 with amazingly good results!
 
Good to see you still using the Combi-Plan tank Keith! Mine has settled down and now leaks very little when I remember to press the ld down hard all around. I've just done two batches of 6 negs in LC29 1+29 9 minutes @ 20c with a water pre-soak - very happy with the results and no sign of uneveness. I have also used it at 1+58 for longer times.

Rodinal is not available locally except perhaps by mail order from Vanbar - they charge a hefty shipping/handling fee and a 500ml bottle ends up costing nearly $40. I have a few drops left in the bottle you sent me Keith, but when that is gone I'll be happy to stick with Ilford developers.

(Sorry for the diversion :eek: )
 
I use 1:100 because I can sit and watch TV for an hour, claiming that I can't be disturbed because I am in the middle of a delicate chemical process.
 
I've never experienced this but when I started with Rodinal I can remember reading that the contrast decreased as you increase the dilution. Also, they didn't like TriX in Rodinal, and I can't remember why, but I have had my troubles with TriX in Rodinal. The article was written in the 1970s just when Rodinal was becoming popular again. I have the article but I can't give you the date because it was not on the pages I have. It is pretty long not like the Pop Photo articles of today. I will scan and send if anyone is interested.
 
I like it because I'm lazy... if I'm shooting iso 400 for instance... I can meter at anything between 320-1600 depending on the situation and change it up mid roll... and I can develop a roll of 100 and 400 in the same tank... just plop pretty much anything in there, and stand for an hour with one inversion at the halfway mark... easy, simple and looks great.
 
Thanks guys.. but what about which film? I mean, I normally don't go Rodinal with anything else other than really high ISO Tri-X (6400 and above) or with APX type films (Silvertone, APX, maybe Efke?).

Are people using the high dilution Rodinal with ANY film?

Cheers,
Dave
 
What you are doing is developing with is a weak developer. This will reduce contrast as the developer sitting at dense silver sites will exhaust faster reducing their final density compared to a stronger dilution. Since sharpness/granularity/density are related, you may get some more sharpness out of the image. Some see this, some do not.
 
I use 1:100 because when developing large format, the weaker dilution is less likely to cause streaking. Also I do most of my developing on a rotary processor, so 1:100 compensates for the constant agitation.

HP5+ is my main film stock, so yeah I use highly diluted Rodinal with it.
 
patrickjames said:
Notice that I said "at that concentration" it is irrelevant. If you add sulfite to Rodinal it changes the characteristics of it. Did I say it didn't? The OP has store bought Rodinal, not mixed from scratch. Sulfite at low concentrations has very little to do with development in a developer such as Rodinal that relies on pH to attain activity.

If you mix "Rodinal from scratch" you don't have Rodinal now do you? You have something that may be similar in characteristics to Rodinal, but has been modified to suite your requirements by adding additional sulfite. The sulfite is secondary (as a silver solvent) to the Hydroxide. If you doubt this try mixing your rodinal substitute without the hydroxide, just the sulfite, and see how much development you get.

I'll leave it at that.
Click to expand...

I think we're talking at cross purposes. I am not talking about adding sulfite to Rodinal.

As part of my own investigations into the "solvent effect" I used gas chromatography-mass spectrometry to analyse three batches of Rodinal to obtain an exact formula for the commercial product. I also measured the specific gravity, pH to four decimal places and a couple of other useful parameters. I obtained most of the components; two I had to synthesize (one I am not even sure I know what it does) because they were not commercially available here. Finding the potassium salts of some common agents which are usually available here as the sodium salts was not as hard as I thought it might be.

I mixed up batches of Rodinal so that the developing components were as they would be in Rodinal 1+25, 1+50 and 1+100. I played with the sulfite so that for each of the three concentrations I had the sulfite of the other two, but with everything else held constant. This was hard, because the hydroxide gets used up a little reducing other components in the developer, but this differs at different dilutions because of shifts in the acid-base eqilibrium and the effect of this on the reducing capacity of the solution. I also mixed up one batch so that there would be no sulfite.

I then developed four short films exposed at half their rated ISO and an Ilford T5 process control test strip using gentle intermittent agitation.

So in the end I had 36 films and 12 test strips developed in Rodinal as follows:

1+25 normal sulfite
1+25 sulfite equivalent to 1+50
1+25 sulfite equivalent to 1+100
1+25 no sulfite

1+50 normal sulfite
1+50 sulfite equivalent to 1+25
1+50 sulfite equivalent to 1+100
1+50 no sulfite

1+100 normal sulfite
1+100 sulfite equivalent to 1+25
1+100 sulfite equivalent to 1+50
1+100 no sulfite

I photographed each frame with a microscope with a scanning back camera at three magnifications representing large, medium and fine image detail and compared the image files using an image analysis program written for this purpose in Zeiss' KS Run format.

I measured the test strips using a densitometer and used ANOVA to compare the curves and the ISO.

I had to immediately remove all the films and test strips developed in Rodinal with no sulfite from the analysis; this formulation caused rapid infectious development that stops just as quickly. The image was thin but very contrasty, way outside any sort of curve shape that could be ISO rated. Further experiments showed that this could not be fixed by extending development. I found that the curves and effective ISO speed had no statistical differences.

I used a Bray-Curtis dissimilarity transformation and generated a non-parametric multidimensional scaling analysis (nMDS - non-metric MDS both finds a non-parametric monotonic relationship between the dissimilarities in the item-item matrix and the Euclidean distance between items, and the location of each item in the low-dimensional space using isotonic regression) and found that the grain assessments grouped out separately from each other. This means that the grain patterns and edge rendition were all statistically different from each other among and between the groups - essentially this means that the grain size and pattern and edge rendition differ both at a given concentration and between dilutions, but not the film speed or curve. The difference at a given sulfite concentration was very interesting, the dilution effect was something I expected.

I then wet printed examples across the samples on Fomaspeed Variant III and developed them all with standard time and agitation in Dektol 1+2. You can see differences in edge rendition and grain patterns.

I then developed films and test strips in commercial Rodinal 1+25, 1+50 and 1+100 and obtained results that did not statistically differ from the previous experiment. This confirmed that my lab-brewed Rodinal is very close to the commercial product.

So what does sulfite do? It preserves the 4-aminophenol as it reduces exposed silver, allowing dilute Rodinal to develop silver effectively. This is reflected, visibly and measurably, in sharper edges and more highly clumped grain as the sulfite concentration is lowered. Why? I guess because local exhaustion occurs more quickly when the 4-aminophenol is less well preserved by sulfite. I have other data that shows that the effect of modifying agitation is about twice as apparent as changing sulfite concentration, but in normal developing, this means you can change the grain and edges more with more dilute Rodinal because the times are so much longer, giving you more opportunity to modify the agitation relative to the total development time.

Sulfite also is largely responsible for Rodinal's very long shelf life.

Next I am moving on to experimenting with ascorbate aminophenol formulae and what happens when you replace sulfite with ascorbate as Patrick Gainer recommends. I am also going to experiment with buffered 4-aminophenol developers that operate at less alkaline pH. I am also going to compare Rodinal with some other developers to see if all that acutance Rodinal is famous for is really there.

I'd like to try to publish this, but I don't think I can legally disseminate the Rodinal composition data. I'm looking into that right now.

Marty
 
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