The card on the left is a 1940s General Plastics style, before the use of the ‘Beauclaire’ branding. It is the only example with the overprinting of “Guaranteed Boilproof” that I have seen.

Circa 1950 Beauclaire.

Joy-Tu Boyl (or ‘Boil’ or some cards) were only advertised from 1947 to 1948, and there were only 2 and 4 hole shirt/trouser buttons.