Early Thermographic Systems. II. Niepce, 1859

Abstract

The thermographic process of Niepce has been investigated. It was concluded that the formation of positive and of negative images, which vary with the nature of the ink and of the sensitized paper used, cannot be caused by a thermographic process. It is impossible to exclude a slight thermographic effect, but as the process was normally used to copy documents, the main factor involved in image formation was the distillation of oils, or other materials, from the object to the sensitized paper and the effect of these oils on the thermal darkening of the paper.