Sepia toning

Sepia toners vary from the older ‘rottenegg’ smelling type to more versatile odourless variable ‘thiourea’ sepia kits such as Fotospeed ST20. These consist of three concentrates – bleach, toner and an additive that changes the colour produced by the toner. They are archival and easy to use. Unlike ‘direct’ selenium and gold toners this ‘indirect’ toner requires an initial bleach stage. This changes the silver into pale yellow silver ferrocyanide, which the toner then converts to stable brown silver sulphide.

To control colour the toner requires the addition of an alkali – ‘solution C’. This colour is variable from yellow-brown, sepia, mid-brown to dark brown. Few paper/developer combinations give that complete range, but it may be achieved by changing the developer and/or paper.

Full vs split toning

The bleach works ‘top down’ from highlights towards shadows, and can be interrupted for split-toning at the light or midtones, or be allowed to proceed through to the blacks for a nostalgi clooking all-brown print with brown ‘ blacks’. Slow coldtone papers need stronger bleach for this, with a longer wash before toning.

Split-toning is achieved with shorter bleach times. The effect may be obvious when toning to midtones, or just the subtlest hint of warmth in the highlights, in which case it helps to dilute the bleach further for better control. These need only short washes before toning. Whilst you can snatch from the bleach early, you should never snatch early from the toner before the less-stable ferrocyanide is all converted. The ‘split’ is controlled in the bleach, never the toner, which only tones the bleached silver, leaving the remaining silver still available for another toner if desired.

There is always some highlight density loss with sepia toning. This is greater with a low-alkali yellow-sepia mix than with a high-alkali darkbrown combination. Anticipate this when printing.