Do you have a pre 1940's banjo by this maker? can you supply us some images?
At the beginning of the 20th c Chicago was a hub of music companies and Tonk Bros slotted into the maize of manufacturers, buyers and resellers and retailers of instruments and sheet music at the quality end of the market.
The philosophy of quality in product and service was laid down by Charles J Tonk and they claimed to be the world’s largest exclusive wholesaler of stringed musical instruments including National Guitars and Washburn banjos, guitars, mandolins and Ukuleles.
It was started in the early 1890’s by the Tonk Bros. and was taken over by Paul Moenning in the mid 1920’s still trading as Tonk Brothers, 623 South Wabash Avenue, Chicago.
In 1928 he acquired the Lyon & Healey wholesaling business and had JR Stewart making Washburn banjos for him claiming $1 million of sales in 1929 when you could buy a National Style O for $60
In 1929 the stock market crashed and the manufacturing business of Stewart went bankrupt, so Tonk Bros bought the factory along with the Washburn name. As the US came out of the depression the industry had slimmed down and Tonk continued to trade with Regal who was building their instruments in the old Stewart factory and wholesaling though companies like Kay and Stella.