Click here to see each week a collection of outstanding photographs. The Atlantic

The Guardian writes in a report about Elliott Erwitt's historic photographs from Pittsburgh, respectively about his new Book Pittsburgh 1950, published by GOST Books. (Pohto Elliott Erwitt: Workman on Wrecking Project at the Point 1950) 

Collodion process, mostly synonymous with the "collodion wet plate process", requires the photographic material to be coated, sensitized, exposed and developed within the span of about fifteen minutes, necessitating a portable darkroom for use in the field. Collodion is normally used in its wet form, but can also be used in humid ("preserved") or dry form, at the cost of greatly increased exposure time. The latter made the dry form unsuitable for the usual portraiture work of most professional photographers of the 19th century. The use of the dry form was therefore mostly confined to landscape photography and other special applications where minutes-long exposure times were tolerable

These days the Spanish photogrpher Jacqueline Roberts uses this more than 160 years old technique to portrait childs with astornishing results. Read more on bored panda (Englisch), how her picture look like.