Sandgren introduced functionalism to the art of bookbinding in Denmark and he was a major innovator in Danish book design.

August Sandgren took an apprenticeship in 1907-1911 and in 1912-19 he travelled and worked throughout Europe, including the Netherlands, Germany, Switzerland and France.

In libraries and museums in Berlin he became acquainted with the work of the English bookbinder T.J. Cobden-Sanderson (1840-1922) from the Arts and Crafts movement, an inspiration for him in the first years.

On his famous full leather bindings, of which he made around 100, the decoration is limited to a gilt frame near the edges of the sides - e.g. a gilt line, pattern or geometric design - and the large central area of the sides are free from decoration, so the quality and colour of the leather is in focus.

Sandgren only used the very best in goatskin or Morocco leather with a beautiful, natural structure, and his bindings are in subdued, darker colours, for example brown or red.

He used marbled sidepaper, handmade by himself, and they were kept in darker colors - brown, black, dark green and blue, and the most beautiful paper has vertical, dense stripes.

He was a great master of typography and justification, he preferred to use the same types as the book itself, he rarely used abbreviations, syllabifications or vertical titles.

Today August Sandgren's bookbindings are discussed and admired in various associations in Denmark, including the Danish Bibliophile Society.

August Sandgren's bindings are some of the most coveted among Danish and international book collectors and bibliophiles, due to their beauty, high technical quality and stylish design.