[4] Though he was initially trained in painting, the retirement of the Netherlands's top restorer Willem Anthonij Hopman necessitated a successor, and art historians Abraham Bredius and Hofstede de Groot nominated Carel for this role.

[4] During his time with Knoedler & Co., and subsequently at the independent practice on Fifth Avenue he opened in 1916, he worked closely with American industrialists Henry Clay Frick, Joseph Widener,[5] and J.P.

[3] After Carel's departure for the United States in 1911, the Haarlem Committee of Supervision nominated his older brother, Derix, to continue restoring the city's twelve Hals group portraits.

[1][13] Like Carel, he worked at the Mauritshuis, developing a close professional relationship with then-director Wilhelm Martin that led to several collaborative projects, often scientific in nature.

For example, in July 1916, in response to a threat of chemical attack, they tested the effects of lye on a series of "dummy" paintings in order to discover which brand of fire extinguisher was best suited to saving an artwork.

[1] Although he published little himself, save for an article in the Kurt Walter Bachstitz Gallery Bulletin, he remained well-occupied with his restoration business in the Hague until his death on December 4, 1932.

[1] Working privately in his studio in the Hague, Martin published widely until his death in 1969, often collaborating with colleagues from the Delft University of Technology and the International Institute for Conservation.