Wedgwood and Davy’s sun prints
1802 (Davy’s account published)
Thomas Wedgwood made silhouettes of leaves and paintings on paper soaked in silver nitrate, but could not stop them darkening. Humphry Davy published the method in 1802.
How it began
Thomas Wedgwood grew up among artists and scientists and knew of the camera obscura. In the 1790s he tried to capture its image on paper or leather treated with silver nitrate. In 1802 his friend Humphry Davy published their results.
How it works
Objects laid on the sensitised paper in sunlight left white shapes where they blocked the light, a photogram. Paintings on glass could be copied the same way. The images in the camera obscura were too faint to register in the time they had.
Why it mattered
It was the first published attempt to make pictures with light and chemistry, and it named the central problem. The pictures could only be looked at by candlelight, because daylight kept darkening the unexposed silver until the whole sheet went black.
Limits and what replaced it
Without a fixer the images were lost. Niépce and Daguerre succeeded with other materials; the fix for silver images, hypo, came in 1839.
Today
None of their images survive; they are remembered as the first serious attempt to make photographs.