The Van dyke brown print is based on the

first iron-silver process, the argentotype,

invented in 1842 by the English astronomer,

Sir John Herschel. Both processes utilizes

the action of light on ferric salts and have

very similar chemistry. Van dyke brown is

considered a printing-out process in which

an enlarged negative or 3-dimensional object

is laid directly onto the sensitized substrate

and then exposed to light. The exposed

areas turn brown while the unexposed

areas wash away.This process is extremely

versatile - the sensitizer can be applied

to a variety of substrates including

handmade papers as well as fine fabrics

such as silk.