Kia ora Chris,
Maybe after 'Fujichrome'? Or Kodachrome? Or Ektachrome...
It's common 'speak' to refer slides being prepared for printing "going to 'chrome", but this refers to Ilfochrome/Cibachrome print process (sometimes also the high-end inkjet Ultrachrome jobbing).
Hmmmm. Happy now you've got us all bugged!?