Caspar used a precise burin technique to reproduce the textures of the Old Masters. He did more than simply copy lines. He translated the soft skin tones of Titian and the structured compositions of Raphael into patterns of dots and cross-hatched lines. His portrait of Felix Mendelssohn Bartholdi shows this control. He captured the composer using a series of marks that suggest volume without the use of colour. His work is defined by a mathematical approach to light and shadow.

Modern collectors value Caspar for the clarity of his vision. His prints offer a way to own classical compositions with a distinct graphic quality. The black and white palette suits contemporary interiors. These engravings provide a link between the Renaissance and the nineteenth-century academic tradition. They represent a period when the engraver was respected for their technical skill.