Toning Techniques

In photography, toning is a photographic process carried out on silver-based (black-and-white) photographic prints to change their colour. Some toning processes can improve the chemical stability of the print and allow it to last longer. Other toning processes can make the print less stable.

Many early prints that exist today were toned with sepia toner.

Most toners work by replacing the metallic silver in the emulsion with a silver compound, such as silver sulfide (Ag2S) in the case of sepia toning. The compound may be more stable than metallic silver and may also have a different colour or tone. Different toning processes give different colours to the final print. In some cases, the printer may choose to tone some parts of a print more than others.

Toner also can increase the tonality of a print. This increases the range of visible shades without reducing contrast. Selenium toning is especially strong in this regard.

Many toners are highly toxic. It is extremely important that the chemicals are used in a well ventilated area. Rubber gloves and face protection should be worn when handling them. Some toners are carcinogens.

Sepia toning

The term ‘sepia’ comes from the name of an artists’ pigment made from the Sepia cuttlefish, found in the English Channel, Sepia officinalis, the Common Cuttlefish.

In sepia toning, chemicals convert the metallic silver in the print to a sulfide compound, which is much more resistant to the effects of environmental pollutants such as atmospheric sulfur compounds. This is why many old photographs are sepia toned—those are the ones that have survived until today.

There are two main types of sepia toners in modern use:

1. Direct Sulphide Toners

Polysulfide or ‘direct’ toners do not require a bleaching stage.

Direct sulphide toners work well with warmtone papers.
Such toners have little effect on cooltone papers however.

These types of toners have the advantage that toning can be stopped when the desired colour is reached, and also partially toned images can be further treated in other toners to produce various other special effects.

Prints toned in direct sulphide toners generally have similar density and contrast – to untoned prints.

These toners can be used at room temperature but they act very slowly – taking up to 30 minutes to reach completion. This time can be shortened considerably by raising the temperature to 100F/38C, but the drawback is that at higher temperatures this already initially strong smelling toning solution – will be even more unpleasant.

Examples of commercially available direct sulphide toners are: Kodak Brown Toner, Photographers Formulary Hypo-alum, and Photographers Formulary Polysulfide.

2. Indirect Sulphide Toners

I.  Sodium sulfide toners – the traditional ‘rotten egg’ toner.
II. Thiourea (or ‘thiocarbamide’) toners – these are odourless and the tone can be varied according to the chemical mixture.

Sodium sulphide toners and non-variable warmth thiourea toners work well with Multigrade papers, but give a rather cold brown image colour on Multigrade IV papers.

Prints toned in sepia toner can be further toned in blue (iron) toner to give a green tone – or, if only partially bleached, a blue/green/sepia split tone.

They can also be treated in a gold toner to produce an orange-red image.

The bleach used is normally a ferricyanide bromide type – which converts the silver image to silver bromide.
The darkening (redeveloping) solution can be a solution of sodium sulphide. However this solution has a very strong/nasty smell – and most users now prefer to use odourless (thiourea) toners.

Odourless toners use an alkaline solution of thiourea to convert the silver bromide image to silver sulphide.
Apart from being odourless, they also have the advantage of allowing the resulting image colour to be adjusted by controlling the pH of the second bath.
The pH adjustment is achieved by adding more or less sodium hydroxide solution to the second bath. More additive gives a colder image tone, less additive gives a warmer image tone.

Prints toned to have a very warm image tone generally have considerably lower density and contrast to untoned prints.

Incomplete bleaching creates a multi-toned image with sepia highlights and grey mid-tones and shadows. This is called split toning. The untoned silver in the print can be treated with a different toner, such as gold or selenium.

Examples of commercially available indirect sulphide toners:

Indirect sulphide toners: Berg Rapid RC Sepia, Kodak Sepia, Photographers Formulary Sepia Sulphide 221, and Tetenal Sulphide.
Thiourea sulphide toners (non variable warmth): Photographers Formulary Thiourea, Speedibrews Speedisepia.
Thiourea sulphide toners (variable warmth): Fotospeed ST20 sepia toner, Rayco Varisepia, Tetenal Triponal.

Selenium toning

Selenium toning is the most popular of the archival toning processes, converting metallic silver to silver selenide. In a diluted toning solution, selenium toning gives a red-brown tone, while a strong solution gives a purple-brown tone.
The change in colour depends upon the chemical make-up of the photographic emulsion being toned. Chlorobromide papers change dramatically, whilst pure bromide papers change little. Fibre-based papers are more responsive to selenium toning.

Selenium toning may not produce prints quite as stable as sepia or gold toning.
However, its appearance is much more subdued than sepia and it is cheaper than gold.
Selenium toning also increases the tonal range available in the paper.

Different printers use somewhat different methods of selenium toning, but most often a fixed (and perhaps rinsed) print is placed in selenium toner solution and then rinsed, treated with hypo clearing agent, washed, and hardened.

Recently, doubts have surfaced as to the effectiveness of selenium toner in ensuring print longevity.

Selenium toners are single solution toners that partly convert the original silver image to silver selenide.
The degree of toning can be varied by changing the toning time or solution dilution.

With cooltone papers, very little colour change results in selenium toners, but it tends to darken the shadow areas of the prints, and tint them purple. The highlights do not change in density however.

Warmtone papers are very responsive to selenium toners. Toning these with higher dilutions (e.g. 1+10, 1+20) of selenium toner – gives a slight cooling of the image tone and a shift in hue towards red.
Used at lower dilutions (e.g. 1+3, 1+5) – a purplish brown can be achieved.

Selenium compounds are extremely toxic, so preparing the solutions from raw materials is hazardous.

The best if you use a proprietary brand, such as Kodak Rapid Selenium toner (this is diluted 1+3 for usage).
Other commercial selenium toners: include Berg Selenium, Fotospeed SLT20, and Maco Selenia.

Metal toning

Metal replacement toners replace the metallic silver, through a series of chemical reactions, with a ferrocyanide salt of a transition metal. Some metals, such as platinum or gold can protect the image. Others, such as iron (blue toner) or copper (red toner) may reduce the lifetime of the image.

Most commercial metal toners are single solution toners – readily available brands include those from Fotospeed, Speedibrew and Tetenal.

Gold toning

Gold toning used alone gives blue blacks, but used with sepia toners produces orange-red effects.

Most commercial gold toners are single solution toners. When used on their own, gold toners will shift the image colour of a print to a blue black. However, when used in combination with a sepia toner – they will produce attractive orange-red colours.

The archival Gold Protective Solution (GP-1) formula uses a 1% gold chloride stock solution with sodium or potassium thiocyanate. It is sometimes used to split tone photographs previously toned in selenium for artistic purposes.

The mechanism involves gold metal being deposited onto the silver of the image.

Examples of commercial gold toners include :- Berg gold protective solution, Photographers Formulary Gold 231, and Tetenal gold toner.

Prints toned in gold toners generally have similar density and contrast to untoned prints – the image being used should receive normal exposure and be fully developed.

Dye toning

Dye toners replace the metallic silver with a dye.

The image will have a reduced lifetime compared with an ordinary silver print.

Examples of commercial dye toners include those from Colorvir and Berg.

Split toning

Split toning involves the use of more than one colour toner.

Split toning techniques are used to obtain different colours for the highlight and shadow areas of prints – by using two toners one after the other.

The table below shows some of these example effects possible.

First Toner / Second Toner = Effect

Sepia / Blue = sepia highlights, blue shadows, green mid-tones
Sepia / Selenium = brown purples
Selenium / Gold = purple-blue mid tones
Blue / Selenium = blue shadows and buff highlights

Some toners for example Kodak T-21 toner (Nelson gold) – tone the highlights and shadows at the same time. These are not so effective for split toning techniques.

Resources

Ilford Toning Guide
Kodak Toners

Kodak Toning B&W Materials Guide



Digital Toning

With the dawning of the digital age, a whole spectrum of toning opportunities is now presented. We can not only emulate the toning of yesteryear but also create a whole fresh palette of new toning ranges. Additionally, toning offers a useful platform for hand-tinting an image.

Because it’s a totally new ground of the toning techniques, we introduce it in a seperate article.

Read Digital Toning Techniques


source 1, source 2

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