Terry
Controlling sepia toning is down to the ratio of thiourea to sodium hydroxide in the toning bath, and the depth of bleaching. For a proprietary brand of sepia toner I would start by diluting the bleach to a third of the suggested strength. For the toning bath, the ratio for a warm toned image is 5-1(thiourea to sodium hydroxide), a mid tone would be equal amounts of each (thiourea to sodium hydroxide), and for dark brown 1-5 (thiourea to sodium hydroxide).
In practice, for a warm tone print, add 50mls of the thiourea concentrate and 10mls of the sodium hydroxide to 1 litre of water. I have found keeping the toning bath warm at around 25degrees helps with the depth and warmth of the tone. I would suggest the example you gave on Wolfgang Moersch’s site, has been bleached into the midtones and toned using a 5-1 mix. Warm toned papers such as MGWT will also give a greater response with sepia toning.
If you are interested, there is a short article about sepia toning on my website, under the heading information.
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