Description of the process (Roger Watson, Curator, Laycock Abbey, 8 February 2017)
First he would have taken a print of the head of Christ and placed that in contact with photogenic drawing paper. This would have created a negative image of the bust of Christ. He appears to have cut out the bust along its edges. This negative and a real oak leaf would have been placed in contact with another sheet of sensitive paper and exposed to the sun. This exposure would have given you the oak leaf in negative (it is) and the head of Christ in positive.
Curatorial description
To produce a photogenic drawing objects were placed on sensitized paper. The areas where light fell became darkened, while covered areas remained light, resulting in a negative image.
