Thanks Chris - I have done that. I have also seen the article - but it is not very illuminating for working on enamel. Firing of course is the issue - but I don't think an enamel would respond well to a slow heating up and a slow cooling down. It's not necessary for liquid gold... Also, I want to have other elements on the piece in addition to the gold: would I fire it first or last if I am also wanting to add graphite and china-paint? I am having a discussion about it with Marci from the PPIO forum - but of course she is not familiar with enamel. Crazing usually happens when the COE's are too different, but I have no information on the COE of this material. I also don't know whether I should use fluxed or unfluxed - and buying one of each would be expensive!

Has anyone ever used Roman Gold on enamel?

It is normally used by China painters. It goes on matte - but you can use a burnishing tool to shine some areas causing a 3D shaded effect like this: https://www.mbam.qc.ca/resources/images/1933/GWeb/1933_Dp_4_IN2.jpg

As far as I can understand Roman Gold is 38% 24k gold and comes fluxed or unfluxed. Fluxed is for raw china and unfluxed for over a china painted surface, so I am assuming unfluxed would work on enamel.

It's $70 for the smallest amount - so I am anxious to get as much information as I can before investing!