During these times of restricted travel, I’m taking the opportunity to teach myself new darkroom skills. Yesterday I looked at drag bleaching …


I came across the technique while reading Barry Thornton’s book ‘Edge of Darkness’. It’s a bleaching method which targets the highlights and middle tones whilst preserving the deeper shadows.

Selenium toners tend to act on dark tones before lighter ones. When selenium reacts with silver in the photographic image, silver selenide is formed which is partially resistant to bleach. So if you partially selenium-tone an image then bleach it, only those parts of the image which did not react with selenium (the lighter tones) are bleached. By varying the ratio of selenium toning to bleaching, you can control the look of the image.


I start with an overexposed print (about half a stop extra exposure) to give me plenty of leeway with the bleaching and to ensure that the highlights are sufficiently recorded. These days I nearly always split-grade print my pictures, so If I have drag bleaching in mind for the print, I would normally burn important highlights with a low grade filter.

For any toning procedure I have found, through several mistakes, that it’s vital to wash out all of the fix from the print. Any fix that combines with bleach will irreversibly bleach the print, preventing any redevelopment work later on in the process. It may also stain the print.

For drag-bleaching I use a Selenium solution at a concentration of 1:8. The time that I leave the print in the toner bath depends on how much of the tonal range I want to preserve from the bleach. One thing to bear in mind is that the paper changes colour when toned with Selenium. I tend to use Ilford MGWT, which tends to an aubergine brown colour if left long enough in the toner bath.

The other thing to anticipate is that the bleach bath will not only bleach the un-selenised tones but it will also change the colour, emphasising the aubergine-brown. At a concentration of 1:8, my selenium bath times are normally in the range of 1.5 minutes to 3 minutes. 1.5 minutes gives me Dmax. 3 minutes gives me colour changes. I tend to test these times afresh each time with the test strips that I used for the split-grade printing.

For bleach, I use a mixture of Potassium Ferricyanide and Potassium Bromide in a 1% solution. This gives me bleaching times of between 2 and 6 minutes.

Once I have toned then bleached and washed the print, I have one of two options: either I fix the print or I redevelop the print using dilute Ilford Multi-grade and then stop/fix. Redeveloping the image can give interesting split tones. You can apply the developer with kitchen paper to selected parts of the image or you can redevelop the whole image and snatch the print when you are happy with the result. To do this with control, I dilute the developer to 1+19, rather than the normal 1+9.


Below, I set out some of my early examples. I’m sure these can be bettered, but it gives you an idea of the results.

Scan of straight print for reference purposes – half-stop extra exposed.
For reference purposes: scan of print after split grade treatment
Drag bleach deep into the tonal range
Drag bleach to produce redevelopment split tones in highlights
Drag bleach without redevelopment.

Interesting experiment – Next thing to try will be drag bleach with Sepia, where in theory highlights should be preserved whilst darker areas will be subject to the bleach?