Which chemical element affects the tone of the print?

[smaidimaita]

Hello!
Just built up my darkroom, just a few things missing, for example the paper developer.
I have a couple of hundreds of Agfa MCP RC paper sheets, so I'll be using them for some time.
If I understand, then it's harder to get cold tone for chloro-bromide papers.
And I don't feel like making soft warm-tone pictures.
So what interests me is -
1) how to get my Agfa MCP RC cold tones.
I think I could mix the developer myself, but the only supplier chemical substances has run out of hydroquinone, and there are not too many photoshops around here.
and
2) I've searched for the chemical ingredients for different paper developers, and what seemes strange to me is that there are 2 very similar developers, and the ratios of the chemical substances are very similar, but one of them is called a warm tone dev., but the other - cold tone.
Here they are:
the warm tone - (GAF-125)

Water (125°F/52°C) 750 ml
Metol 3 g
Sodium Sulfite (anhy) 44 g
Hydroquinone 12 g
Sodium Carbonate (anhy) 65 g
Potassium Bromide 2 g
Cold water to make 1000 ml

and the cold tone - Burki and Jenny
Water (110°F/43°C) 750 ml
Metol 3 g
Sodium sulfite 40 g
Hydroquinone 12 g
Sodium carbonate (mono)* 75 g
Potassium bromide 0.8 g
Water to make 1000 ml
Only the Potassium Bromide and Sodium Carbonate ratio changes noticeably.
So which elements change the tonality?

Thanks.

[climbabout]

Generally speaking metol is a soft working developing agent and hydroquinone is a more aggressive agent. The potassium bromide is the chemical that in increasing amounts will warm up the tone.
Tim Jones

[Pragmatist]

This is not true of brom or chlorobrom papers unless they are specifically a "warm" type. You may achieve a "cooler" tone by the use of a glycin based developer such as Ansco 130, or one of the Amidol preparations. Photographers Formulary sells both, as Formulary 130 & Formulary Amidol, Formulary Weston Amidol.

You may wish to experiment somewhat with KRST (selenium toner) to achieve a richer black look. However on most papers that lean toward warm tones by design, selenium can add to that effect, moving toward a sepia depending upon time and dilution. If you really want cool/cold tones, consider using one of the developers listed above with Ilford Ilfobrom Galerie FB (deep, rich blacks), or Ilford Multigrade IV Cooltone RC (crisp, great tonality, very cool).

[Gerald Koch]

The easiest way to cool the tone of paper is to add benzotriazole to the developer. This was available as Ilford IBT Restrainer or Edwal Liquid Orthozite. The amount added controls the image tone. A 0.2% solution can be used. Start with 5 - 10 ml/l to start. Benzotriazole can be obtained from www.techcheminc.com.

[smaidimaita]

Thanks. Got the idea.

[Tom Hoskinson]

Yes benzotriazole is the stuff to add for cold blue-black tones.

For warm tones, Hydroquinone, Catechcol and Pyrogallol based paper developers are often used. P-Aminophenol developers like Rodinal also produce warm tones on paper.

Here is a British Journal Warm Tone Paper Developer

BJ Warm Tone Developer for Chloro-Bromide Papers
Water-------------------------------------------570ml
Potassium Metabisulfite-----------------1.3gm
Soda Sulfite (Crystal)-----------------------28gm
Potassium Bromide---------------------------4gm
Pyrogallol-----------------------------------4gm
Sodium Carbonate(Crystal)---------------28gm

Published inThe British Journal Photographic Almanac, 1925, page 278

Conversions from 1925 UK units to Metric were made with the digitaldutch WWW Converter and rounded up


http://www.digitaldutch.com/unitconverter/

[Gerald Koch]

British Journal Warm Tone Paper Developer

In the formula, I assume that crystal stands for decahydrate sodium carbonate and hexahydrate sodium sulfite. To convert the amounts to monohydrate sodium carbonate and anhydrous sodium sulfite you need to divide the amounts by 2.33 and 2.00 respectively.

[Photo Engineer]

In the argument of warmtone vs cold tone, the best solution is to use a warmtone paper in a warmtone developer and then back off to a cold tone developer or mixture of these to adjust the tone to your liking.

Toning is often best done in the emulsion itself.

PE

[Tom Hoskinson]

In the formula, I assume that crystal stands for decahydrate sodium carbonate and hexahydrate sodium sulfite. To convert the amounts to monohydrate sodium carbonate and anhydrous sodium sulfite you need to divide the amounts by 2.33 and 2.00 respectively.

Thanks for the clarifications, Gerald.

[dancqu]

Published inThe British Journal Photographic
Almanac, 1925, page 278.

I like that. The 1925 Almanac. They didn't by
any chance suggest some papers which work
well with that developer? Dan