Both Jan l'Admiral and his younger brother Jacob took apprenticeship to Jacob Christoph Le Blon (1667-1741) during his sojourn in London, the latter who is regarded as the pioneer of modern colour-printing. Jan worked with the famous Leiden anatomist professor Bernhard Siegfried Albinus (1697-1770), publishing a total edition of six colour mezzotint prints between 1736 and 1741, which comprised two prints after drawings by the Amsterdam professor of anatomy Frederick Ruysch (1638-1731). The coloured mezzotints depicting the vascularisation of the intestines, human skin and the brain. L'Admiral's plate after Ruysch's drawing of the brains of a premature fetus is his most appreciated work.
After Le Blon's death both his pupils l'Admiral and Jacques Fabien Gautier d'Agoty (1717-1786) would claim to have invented the colour printing technique themselves, although they only added a fourth colour (black) and did not invent the technique itself.
L'Admiral also etched the portraits to the 1764 translation by Jacobus de Jongh of Karel van Mander's "Het leven der doorluchtige Nederlandsche en eenige Hoogduitsche schilders".
Drawings by Jan l'Admiral are of the greatest scarcity. Two gouache drawings by him of the skeleton of a hand and a foot preserved in the collection Rijksmuseum, Amsterdam.
 Ludwig Choulant and Frank Mortimer, History and Bibliography of Anatomic Illistration. Maurizio Martino, 1994. Translated edition of the original edition of 1852. p. 267-269.
 Jan l'Admiral, Anatomical study to the skull of a premature fetus.
Rijksmuseum Amsterdam, inv. no. RP-P-1961-523
 Karel van mander (Jongh, Jacobus de (transl.). Het leven der doorluchtige Nederlandsche en eenige Hoogduitsche schilders. Amsterdam, Steven van Esveldt, 1764.
 Jan l'Admiral, Skeleton of a hand. Gouache, 228 x 196 mm.
Rijksmuseum Amsterdam, inv. no. RP-T-1910-35
 Jan l'Admiral, Skeleton of a foot. Gouache, 239 x 375 mm.
Rijksmuseum Amsterdam, inv. no. RP-T-1910-36