Abstract This study describes an antique watercolor box from Reeves with 24 colors in cakes, dating around 1800. A second box from T. Reeves & Son dating between 1790-1799 is added and described. A concise chronological overview shows which family members of the Reeves’ family and their associates lead the firm during the Regency period. Old city maps of London indicate the various shop locations and a brief look is taken at early 18th century shops of color men and the production of watercolor paint in cakes. The dating of the watercolor box and its contents raise a number of questions. To position the box with contents in the correct period, an overview of available trade cards is consulted. Stamps on cakes are linked to the various family members, who led the Reeves firm in the Regency period.Based on the contents of comparable watercolor boxes relationships are established with user groups, quality criteria of the paint and color theories in the 17th and 18th century. An attempt has been made the 17th and 18th century color theories, in which light refraction, the distinguishing of colors and physical laws are important, to connect with pigments, tinctures, and mixing paint colors to make visual art works possible. Overviews of pigments and paint tincture by a number of authoritative authors in the 17th and 18th centuries are highlighted. The hidden selection rules of the colors and their conscious positioning in the box are discussed. Instructional illustrated is the visually completing of the missing paint cakes. Also included are some overviews of the selection of watercolor paint cakes in comparable boxes. The restored boxes and their contents are illustrated in a number of images. Finally, each of the 24 color cakes in the box of 1799-1800 is treated by their description in the 18th century literature. An extensive overview, with mainly 17th and 18th century sources on pigments, dyes, paint preparation, color theories, etc., is affixed. Added are contemporary authors who have written about the Reeves firm. Finally, nine attachments are available about a scheme of painting substances by Robert Dossie, the management structure of the Reeves firm till the 20th century, a pricelist of Robert Ackermann's paints in 1818, a text fragment in Ackermann’s Repository of Arts (1813), a reconstructed advertisment text in the Derby Mercury of April 10, 1794, a recepy for a binding mixture to make watercolor cakes, an article about an other way of making watercolor cakes of dough, text from W.T. Whitley about ‘Artists and their Friends in England’ during the Regency period and a list of authorities in the 18th-century literature on colors in the form of tinctures, based on natural resources and natural solvents and binders. (Last update August 15, 2023)