Polychrome was a Duco paint, produced by Du Pont, there is an article on their site here.
Sadly it adhered poorly to bare steel, and most, though not all of these ukes have shed large expanses of paint. I know of one that is almost mint yet sits in it's case with all it's coat of paint loose like a snake's skin!
1931 National Triolian Ukulele
Small body - Polychrome finish
serial number 507
