Cyanotype, also known as Blueprint, is a 19c form of very simple photography without a camera. Light sensitive paper is handmade by painting on an iron oxide solution in dark conditions and letting the paper dry. The paper, when taken into the sun, absorbs light and turns coppery grey. The object placed on the paper blocks the sun and this remains a white negative, while the rest of the paper exposes. The oxides are then washed away with cold water and a Prussian blue negative image is revealed. Images can be made with direct contact with objects (photogram) or with an acetate or film negative.