Rackham's illustrations were chiefly based on robust pen and India ink drawings. Rackham gradually perfected his own uniquely expressive line from his background in journalistic illustration, paired with subtle use of watercolour, a technique which he was able to exploit due to technological developments in photographic reproduction. With this development, Rackham's illustrations no longer needed an engraver (who lack Rackham's talent) to cut clean lines on a wood or metal plate for printing because the artist merely had his works photographed and mechanically reproduced.