Lot 81426 – Spanish Colonies, Río de Oro – 1907 4p in se-tenant pair with 3p, three trial proofs with impression in black on paper, one impression painted black around the area of design to concentrate the light, also an impression

1907 4p in se-tenant pair with 3p, three trial proofs with impression in black on paper, one impression painted black around the area of design to concentrate the light, also an impression of the pair on blued paper. A scarce set of three trial productions towards Sperati’s final manufacture of the 4p error of colour; a scarce documentation of this issue on which Sperati worked through both photo-lithography and typography using engraved copper plate.