Swedish born, in US as a baby. Career initially consisted of bouncing around New York newspaper art departments until he his first assignment, a plumb one, painting a cover for The Munsey. With further Munsey work, he did covers for Success, Harper's Weekly, Life, Sunday Magazine, Home Life, Modern Priscilla, Judge, and People's Popular Monthly. Ad assignments included Ferry's Seeds, Swift's, Falstaff, and Vitralite. He was so popular, he was reprinted in posters and calendars. When Sandberg, like others, was asked to mimic the fade-away style of Coles Phillips, he fulfilled his assignment brilliantly and this became a curse with time. Other artists (Leyendecker, Stanlaws) did fade-aways, but Sandberg alone was saddled with "copying." Sandberg was capable of far more than his excellent fade-away work and deserves a re-evaluation.

The blurb below appeared in Time magazine, 11 July 1932, under "Clarion Call"

The American Artists Professional League, long chafing at inroads of foreign artists on their trade, offered a $10 prize for a patriotic U. S. art slogan. Last week Commercial Artist Valentine Sandberg won the $10 but the League made a few changes. He had put his clarion call in a design of crossed artists' brushes. The League added a compass, a modeling tool and a crayon to symbolize all its members. And it changed Artist Sandberg's slogan, "Choose American Art" to "I Am For American Art," the design from a rectangle to an oval, the inscription "American Artists" to "The American Artists Professional League."