Wolfgang Moersch Photochemie
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Toning in sulphur
Part 1

Wolfgang Moersch
Wephota Baryt Brillant
bleached to the mid tones, toned in thiourea (Agfa 525)

Apart from ready made toner from shops, there are numerous free formulae. The amount of recipes suggests different results, but there is limited variation possible with them. Instead of relying upon those formulations, you should try to use different papers, if you are unhappy with the toning results on your standard paper. Deep brown or luminous red-brown hues, which once could be created with numerous bromide-silver papers, are a thing of the past. Most papers today, even if based on a traditional formulation, carry a mixed emulsion. Today (2007) there are five bromide papers still in the shops, which can be toned with thiourea to deep brown hues:
  1. Kentmere Bromide (graded)

  2. Adox Nuance (graded)

  3. Fomabrom (graded)

  4. Fomabrom Variant III

  5. Adox Fine Print VC

Most papers today carry a mixed emulsion with a high amount of chloride silver, which tones yellow. Agfa MCC and Ilford Multigrade IV give rather pleasant tints.

Pre-toning in sodium-sulphur toner before bleaching results in deep brown hues with some papers. Rinse between all steps of treatment.

Agfa MCC sulphur toner, bleach, again sulphur toner

Modern day warmtone emulsions can also be developed more or less colourful right away. The expenditure is a lot higher and more time consuming than even the most complicated process of toning. It is possible though, to redevelop the image in a suitable developer after bleaching. This allows you to observe the process in room light. As mentioned earlier, warmtone paper has a tendency towards yellow tints. This can be altered if you go to the trouble of playing around with both the toner adjustments and the characteristics of different papers.

Formulations of sodium-sulphur toners are not as diverse as to focus on them in here. Colour variation depends more on which bleach bath you use and to which degree bleaching is applied. Odourless toners in shops are thiourea toners. They all contain bleach and toner concentrates. Some of them allow fine tuning of the colours by adjusting the pH-value. With self-made formulations as well, the higher the pH-value, the darker the brown tone.

The bleach bath

For a start, it does not make any difference which formulation is used to transfer the image silver into a silver salt. For that purpose most bleach contains, potassium ferricyanide and potassium bromide. The ratio between these two substances has little effect on the result of toning, but the higher the content of bromide and the higher the pH-value, the faster will the bleach work. Of all recipes you can make concentrated stock solution that you can dilute as you require.

IMPORTANT! Before bleaching, the print has to be thoroughly rinsed. Remains of the thiosulphate of fixing would make the bleach be a reducer and redevelopment would be impossible. At least the highlights would vanish irretrievably. If you use a toner that is highly alkaline, with some papers it is advisable to harden the gelatine to preserve the brilliance of the paper surface.

Agfa 500 - working solution 1 litre 60g potassium ferricyanide, 4g potassium bromide
Agfa 501 - working solution 1 litre 50g potassium ferricyanide, 10g potassium bromide
Agfa 502 - working solution 1 litre 30g potassium ferricyanide, 50g potassium bromide, 10ml ammonia

Concentrate with the same or different weight proportion to 1 litre solution e.g. 100:100g, 75:25g, 30:90g dilution of working solution 1+5 to 1+20.

Agfa 502 has an unpleasant smell, due to the ammonia, but bleaches sweepingly within seconds. It takes a little bit longer for the residue colour to be washed off the paper, even if the bleach was used only for a short time. If the content of red prussiate of potash is low, rinsing has a quicker effect. Too short rinsing times can result in yellowing of the whites when toning, irrespective of which bleach is used.


As mentioned earlier, it is of no importance which one of the bleach baths is used. The resulting brown tone depends on the form of the silver that was removed, meaning on the composition of the emulsion, the ratio of Ag Cl : Ag Br. A high content of bromide silver promotes the formation of deep brown hues.

Sodium sulphide solutions of 0.5 to 2% strength are easily prepared and (after bleaching) tone quickly within 30 to 60 seconds. Using longer toning times, the toner also reaches the areas, which have not been bleached. Even if a shift in image tone is not always clearly visible, the stabilizing effect on the silver is obvious. (compare to bleach after toning)

Solutions of sodium sulphide and lever of sulphur smell unpleasantly like rotten eggs. This smell gets worse in the first rinse water. The sulphur hydrogen, which is released is a health hazard and can cause fogging on unexposed photo material. Danger detected - danger warded off?

In a darkroom with no ventilation and little supply of fresh air, you should not use sulphur solutions. If you don't want to miss out on the advantages of straight sulphur toners, you can rule out health risks by toning outdoors. Water the print twice before you return indoors.

An alternative are odourless thiourea toners. It is not really necessary to add potassium bromide, since the alkalinity of the toner can be created with either caustic alkali or carbonate.

Alkalische Thioharnstoff-Kaliumbromidlösung 1 Liter
Agfa 520 - Thioharnstoff 5g, Kaliumbromid 40g, Natriumhydroxyd 3g
Agfa 525 - wie oben aber mit 15g Natriumhydroxyd (Ätznatrium)

1 litre alkaline solution of thiourea and potassium bromide:
Agfa 520 - 5g thiourea, 40g potassium bromide, 3g sodium hydroxide
Agfa 525 - as above, but with 15g sodium hydroxide

Avoid skin contact with sodium hydroxide and rinse thoroughly if accidentally contaminated!!!

Both baths are long-living. If the effect is deteriorating, you can regenerate with NaOH. 520 produces a yellowish hue, which is more delicate. 525 is stronger with a dark nuance. If only a touch of warmth is to be added in the highlights, 520 is the better choice. This also applies to double toning with iron blue toner, which will be discussed at a later stage.

All thiourea toners are highly alkaline! Fresh solutions start toning abruptly. It is an early sign of exhaustion of the toner, if the print is not fully toned after 30 seconds. Instead of extending toning times to one minute and above, you should regenerate with alkali. If prints are left too long in highly alkaline baths (here it goes up to pH 13.4) the gelatine can soften, resulting in a dull surface after drying. For that reason toning times should not exceed one minute. Some hardened papers survive such tortures for a couple of minutes without showing a sign of damage, but other brands react extremely sensitive, especially when the paper comes fresh from the factory. If surface problems occur already with shorter times of toning, drying in-between can be a remedy. Otherwise the gelatine has to be hardened prior to toning (see hardener).

Warmtone papers: Select VC, Forte Polywarmtone, Bergger Prestige

Chloride silver emulsions and mix emulsions with a high content of chloride silver tone in a yellow tint, after bleaching. This is irrespective of the nature of the toner and little dependent on the composition of the bleach. It does not make a difference, whether the toner was thiourea (like here) or sodium sulphide or polysulphide.


Bleach ferricyanide, bromide 5:20g/L 8sec,
= highlight bleaching
Toner 525 30sec

Ferricyanide, bromide 5:20g/L 30sec
= bleach to the shadows

toned in 525 30sec
If you bleach warmtone papers the bleached
areas will become yellowish,
even if you use the toner 525 that is highly alkaline

If the thiourea toner is adjusted to be strongly alkaline, pure bromide silver papers, iodine silver papers, or chloride silver papers with a low content of chloride silver tone to dark brown tints.

This table shows some configurations of my thiourea toner (MT3 Vario) combined with such papers. The more alkaline the solution, the darker the colour.

Toner = thiourea, starter = alkali

configuration bright yellow dark yellow redish brown mid brown dark brown
toner 50ml 50ml 50ml 50ml 50ml
starter 30ml 60ml 90ml 130ml 180ml
waterr 900ml 900ml 850ml 800ml 750ml

Dilute the bleach concentrate of MT3 between 1+10 and 1+50.

Ilford MGIV in SE6 BLUE

MT3 Vario-sulphur toner

If only the highlights are to receive a warm tint, bleach shortly in a dilution of 1+20 to 1+50. The higher the dilution, the smoother will the transitions be. Here, bleach was in 1+30 dilution for a duration of 40 seconds. The toner was in configuration B for 30 seconds.

In the same toner configuration the degree of bleaching determines the image tone. Left picture: bleach 1+40 for 3 minutes, right picture for 2 minutes. On Ilford MG IV in SE3 COLD.

On Ilford MG Warmtone the bleaching progress is faster than on MG IV. After bleaching the highlights in 1+40 for 30 seconds, I toned in configuration D.

© Nick Hermanns
Select Ivory/ Forte PW17
Bleached to the mid tones, toner configuration 50:100:850

Bleached to the mid tones, toner configuration 50:50:900

Kentmere Fine Print VC
Two bath development in Catechol/Sepia

Bleach 1+40 30 sec,
Toner configuration E 30 sec

Kentmere Kentona

Configuration E results in a red-brown image tone with high density in the shadows, even if the print was fully bleached.

Due to its high silver content ADOX Nuance can
be toned in MT3 towards bright yellow tones as
well as red-brown or warm black hues.

An even wider variety of tones can be reached
by pre-toning in selenium or sodium-sulphur.

Left the untoned print

Bleached in 1+40 for 1:30 minutes

Toner configuration C red-brown

Bleach in a high dilution, if only the highlights are to receive a touch of warmth.

Bleached in 1+20 for 30 seconds

Toner configuration A bright yellow

Bleached in 1+10 for 30 seconds

Toner configuration E dark-brown

Often it is an advantage for the image contrast to stop the bleaching process before it wipes out the deepest shadows.

Pre-toned in selenium 1+10 for 2½ minutes
Bleached in 1+20 for 1 minute

Toner configuration C reddish-brown

Pre-toned in MT5 (toned directly with sodium sulphide)
1+10 for 1 minute
Bleached in 1+20 for 1 minute

Toner configuration C reddish-brown

The toning effect is not visible until bleached.

If you want the toner to reach the shadows fully, you would have to allow bleaching to go just as far in the shadows. This would mean a loss of contrast and density. Instead of this, you can pre-tone with either selenium or sodium sulphur to protect the shadows from being bleached away.

If you use selenium toner, depending on the duration of toning, you protect either only the shadows or also the mid tones. As selenium toner always starts in the shadows it is a question of toning time whether the mid tones are protected or not. Solutions of sodium sulphide, on the other hand, affect the complete range of tone values. Pre-toning in sodium sulphide for only 1 minute is very effective and leaves only little silver for bleaching. There is only little loss of density in the bleach. Only now is the colour of toning visible. Beside the silver-sulphide from toning there is a small amount of silver salt left, which can also be transferred into silver-sulphide by sulphurising. For this purpose you can either tone again in MT5 (sodium sulphide) or in MT3 (thiourea).