Direct Carbon (Fresson) Magnification
Image Structure
While direct carbon is a true photograph (rather than a photomechanical reproduction) it does have a distinctive reticulation pattern visible under magnification. Using raking light the reticulated binder has a slight relief. Due to the proprietary nature of the process, it is not known why or how the reticulation pattern is formed. It is similar to the pattern seen in the collotype process, but appears more spindly and random. Because the image is made up of pigment, pigment particles may also be visible.
While direct carbon is a true photograph (rather than a photomechanical reproduction) it does have a distinctive reticulation pattern visible under magnification. Using raking light the reticulated binder has a slight relief. Due to the proprietary nature of the process, it is not known why or how the reticulation pattern is formed. It is similar to the pattern seen in the collotype process, but appears more spindly and random. Because the image is made up of pigment, pigment particles may also be visible.
What to look for: A random reticulation pattern that has a slight relief using raking light. Pigment particles may also be visible.
With 10x magnification, a distinctive reticulation pattern is visible.
With 30x magnification, the reticulation pattern is visible. Pigment particles may also be visible.
Higher magnification reveals the presence of pigment particles as well as the reticulation pattern.
Layer Structure
Direct carbon has a two layer structure consisting pigment suspended in a binder (likely gelatin) on a paper support. It is a dichromated colloid process so that the binder is thicker in the shadows and thin or absent in the highlights.
Direct carbon has a two layer structure consisting pigment suspended in a binder (likely gelatin) on a paper support. It is a dichromated colloid process so that the binder is thicker in the shadows and thin or absent in the highlights.
What to look for: Paper fibers will be visible, particularly in the mid-tones and highlights.
With raking light and 50x magnification the image has a slight relief where binder is present. Pigment particles and paper fibers are also visible.
Direct carbon typically have a two layer structure.