blueprint photogram process

Blueprints photograms, or cyanotypes, are created by exposing paper or fabric, coated with light sensitive iron salts, to sunlight, which creates an intense Prussian blue negative of an object placed upon it. The discovery of this process by Sir John Herschel was made public in 1842 and used as a way of accurately copying architectural plans and engineering drawings (blueprints). As other newer photographic methods improved, the cyanotype fell out of favour and this simple yet beautiful process is now rarely seen.

Once developed, the images are permanent and the classic bright blue colour can be controlled to create a palette of subtle tones from palest duck egg blues and deep marine tones, through to sepia and dense inky blacks.

  Photogram samples and sketchbook pages

Images are created by either exposing the object directly onto the surface of the cloth, or by using large scale negatives. The fabrics are exposed in sunlight and the depth of colour achieved depends on both the length of exposure time and the strength of the sun. Overcast winter skies give more delicate blues compared to images exposed in bright summer sunshine. 

The nature of the process means that each image is totally unique.