Method

The proper treatment of the plates was the result of many tests carried out with the Lumière Brothers with whom Tournassoud collaborated on a friendly basis: he worked closely with them in the development of the Autochrome plates which he experimented with since 1905. Tournassoud exercised a master's control in the darkroom: He made all his own prints in his darkroom in Montmerle s/Saône, most of the time using chamois paper. The formats of paper he used are: 24x30, 30x40, 40x50 or 50x60.

To better understand Tournassoud's method, a close examination of the plates is necessary: it was indeed not unusual for him to touch up his negatives by means of a translucent varnish in order to open the shadows or to neutralize an awkward background. Tournassoud sometimes employed black lead in his portraits to emphasize the features of the face or to deepen the shadows and, finally, on rare occasions, he hand colored his prints with watercolor or pastels.

It is also possible to understand the "hidden tricks" by which he would manage his astonishing portraits of animals, by looking at the negative plates!

Tournassoud's archives reveal many silver Gelatin-bromide plates (black and white) whose subjects are identical to those of the Autochrome plates. It was indeed possible to use the same large format camera to produce a black and white negative as well as an Autochrome plate: all that was necessary was to change the used plate, to adjust the exposure time (much longer for the Autochrome plate), to add a yellow-orange filter for the Autochrome, to readjust focus and to ask the sitters to keep their pose during all this time, or to use two cameras!