Roy, well, not oil but a thin film of soapy water. Described here: http://www.davidhazy.org/andpph/text-colors-in-thin-soap-films.html cheers, Andy > On Nov 10, 2019, at 4:59 PM, PhotoRoy <photoroy6@xxxxxxx> wrote: > > Andy, > Thin film of oil? > Roy > >
