His most famous project was the reproduction of the Liber Veritatis by Claude Lorrain. This collection of two hundred plates translated Lorrain's wash drawings into a mix of etching and mezzotint. Earlom chose a specific brown ink to replicate the original sepia tones of the drawings. His method allowed for soft transitions between light and shadow. Works like Tobias and the Angel and The Blacksmith show his ability to create atmosphere without using the hard lines of standard engraving.

Collectors today value Earlom for his skill in representing different textures. His prints of cattle and mountainous terrain offer a sense of physical presence. The restrained palette of the Liber Veritatis series provides a quiet alternative to more colourful art. These prints function as a link between classical European composition and the tonal experiments of late eighteenth-century British art.