Mike I use something similar, I get it from house to home in Thirroul. It was all ok on my test panels, i also tested food dye smeared over the blank before glassing with epoxy and it bonded well on the test pieces..
Im hoping to use it to hide some seriously shoddy glass work....
I’ve used that brand for pins and colour matching repairs. The large bottles are base / background colours and are not as strongly pigmented as the colours in the tubes . Look for Series 2 and above for strong pigments.
I stopped using the Jo Sonja brand and switched to Mattisse from the local artist supply , much better quality and they have an acrylic ink which does perfect pins.