Formula?

[glbeas]

I've been looking for the posting with the split developer formula with hydroquinone replacing the pyro part and can't find it. Can anybody help?

[fhovie]

Split D-23?

Bath A
1liter water to make
85g Sodium Sulfite
6.25g Metol

Bath B
1liter water to make
12g Sodium Metaborate

Bath A 4 minutes, Bath B 4 minutes - Temp not critical - emulsion type not critical

[glbeas]

Npe, this one is hydroquinone replacing the pyrogallol in a pyro type developer.

[Donald Miller]

Are you wanting a formula for a paper developer or a film developer?

[Tom Hoskinson]

If it was a film developer, it may be one that I posted.

I posted a variation on a Pat Gainer formulation that replaced the pyrocatechol in Sandy King's Pyrocat-HD, 1:1 with hydroquinone.

The recipe worked and produced good stain and tanning, but it had lower activity and the tonal values were not quite equal to those produced by the original Pyrocat-HD formulation (based on blue channel densitometry plus A,B comparison of print densities and tonality).

The formulation was only split in the sense that it was presented as 2 concentrated stock solutions formulated for maximum shelf life - like Pyrocat-HD.

[Tom Hoskinson]

Addendum:
If you are concerned about safety and the environmental impacts of pyrocatechol versus hydroquinone, IMO they are pretty much equal.

Both of these substances occur naturally and are ubiquitous in the natural environment.

Neither one appears to be a significant health or environmental risk if handled with reasonable precautions (dumping of massive amounts - like recently happened in China - creates problems). Take a look at the MSDAs for both substances. Also look at their WHO evironmental impact assesments. They are on the internet.

[glbeas]

Thanks Tom, that's just what I was looking for! I have a jar of hydroquinone I want to play with, and thought that would be a good project, so I wanted to see what else to get for it.

[gainer]

Just as an experiment, you might try this: dissolve a teaspoon of sodium carbonate in 250 ml water, and a teaspoon of hydroquinone in another 250 ml water. Load a test roll in a tank, mix the two solutions and pour. I would suggest a trial time of 6 minutes. I use this developer as an intensifier for negs that were underdeveloped in a non-staining developer. I bleach the thoroughly washed neg in a ferri-bromide solution,wash it, and in full room light or even daylight, redevelop it in that soup to completion.

The color of the added image is redder than that from PMK.

[gainer]

I followed my own advice. 6 minutes was just about right for 400TX 35 mm. Gradations are good to my eye. Perhaps a little bromide would help, but fog was not a serious problem for silver printing. The neg printed well on VC paper. Grain was a little bit high on TX, but I think sharpness is good. It ought to be worth a try on LF. It's simple enough, will help use up your hydroquinone before it spoils, and you might like it, who knows.

The solution looks exhausted the minute you mix the two parts. You will be tempted to add sulfite. Sulfite prevents the stain from forming if you add too much, and too much is a tiny amount. It will last long enough to do your film without sulfite.

At the least you will learn something you may not have known, that was known many years ago and lost in the rush to embrace the scientific belief system rather than the scientific method.

[skahde]

Thanks Tom, that's just what I was looking for! I have a jar of hydroquinone I want to play with, and thought that would be a good project, so I wanted to see what else to get for it.

If I were you I would use that hydroquinone were you need larger amounts and make the IMHO best use of it: paper developers.

Stefan