Sepia toning - a digital imaging guide

We've all seen those old photos of grandma's that had lovely olde-worlde brown tones. While some are old images that were badly processed and have turned a brown colour because they've stained with age, most were deliberately made this way using a process known as sepia toning.

A sepia toned print not only gives a pleasant tonal range, it also has a longer archival lifetime than an untreated print, because silver sulphide is more stable than pure silver.

What you need
Sepia toner
Cost: About 5
Why you need it: Comprises two parts (A and B) A is the bleach that removes the black tones and B is the toner that brings back the detail and gives the bleached print its brownish tone.

A photograph printed on black & white paper

Three plastic trays big enough to cope with your paper size
Cost: About 10
Why you need them: A set of trays makes it easier to handle the print while toning. Make sure they are at least the same size as the print preferably bigger so you have room to slip your fingers down the side to pick up the print. 
Alternatives: You could use just one print and pour out the solutions after each stage. You can also use cat litter trays or seed trays without holes. If you do printing you should have a set already that can be used providing you wash them out thoroughly after use.

Rubber gloves
Cost: About 5
Why you need them: If your skin is sensitive you can easily develop a rash when using chemicals so you should always use either gloves or print tongues to handle the prints.
Alternatives: A well ventilated area to work in preferably with running water.

1 litre mixing jug
Cost: About 4
Why you need it: Most sepia toners come in either powder or concentrated liquid form so you have to mix them with water to make a working solution.
Alternatives: A cooking measure can be used, but make sure you never use it again for the kitchen.

Two 1 litre containers to store the chemicals 
Cost: About 4
Why you need them: Sepia toner can often be reused so you can keep it made up in suitable containers.
Alternatives: Old pop bottles can be used but make sure you place a big warning label on and keep them well out of the reach of children.
 
A squeegee 
Cost: About 9
Why you need it: Use this to wipe water off the print so dries quickly without water marks.
Alternatives: A wiper blade from a car can be used, but make sure it's not worn or you'll scratch the print. If you don't use a squeegee, try to hang the print up or stand it vertically so water drains off quickly.

2 Pre soak your prints that you are going to tone if the are dry

3 While the prints are soaking prepare the Sepia toner. It usually comes in two parts. Part A is the bleach bath and part B is the toner, both are mixed with water. Pour the bleach mix into the first tray, fill the second with water and pour the toner into the third.

4 Take the print that you want to tone and slip it into the bleach bath and agitate  constantly. This converts the silver image back into silver bromide and makes most or all of the image disappear. The bleaching time, along with print contrast and paper choice, determines how deep the sepia tones will be. A print that is left in the bleach longer will result in deeper sepia tones while a darker grey/brown tone can be produced by only partially bleaching the image. As a guide bleach for between two and eight minutes

5 Thoroughly wash the print for about two minutes to remove any trace of bleach from the paper.

6 Slip the print into the toner, which converts the silver bromide to the brown silver sulphide.

7 Wash the print for about 30 minutes, ideally in several water changes to save using running water.

8 Dry it 

Tip 2
The emulsions used in photographic paper contain either silver bromide or a mix of silver bromide and silver chloride. An emulsion using silver chloride gives a deeper, rich, brown tone.

Tip 3
Try toning several identical prints, varying the time to produce different degrees of toning. Also try the same print exposed at different levels or on different grades of paper. Then you can find a suitable combination to use in future toning sessions.

Types of toner
Sulphide based sepia toner
This is the type of toner that gives off a smell of sulphur that's like bad eggs Hydrogen sulphide is also poisonous so you must work in a very well ventilated room. It makes a yellowish brown image and the colour isn't controllable.

Part A (Bleach) comprises:
Potassium ferricyanide
Potassium bromide

Part B (Toner) comprises:
Sodium sulphide

Odourless sepia toner
Using Thoiurea (Thiocarbamide) instead of sodium sulphide results in a much more pleasant odourless solution.
You also have much more control of the colour because Thiocarbamide toners allow a range of tones depending on the amounts of thiourea and sodium hydroxide in the toner. Increasing the thiourea content and reducing the sodium hydroxide content produces a lighter brown.

Part A (Bleach) comprises:
Potassium ferricyanide
Potassium bromide

Part B (Toner) comprises:
Thiourea 
Sodium hydroxide

Several manufacturers produce ready-made sepia toners including Fotospeed, Kodak, Jessops and Paterson. You can also buy the raw chemicals from the likes of Silverprint and Rayco.