After firing enamel on china it may blister up.
If it happens, the bubbling was likely too much oil. It could be fixed by putting new layer of enamel over it, but I would suggest using base for gold or non ping since enamel does have a tenancy to pop off.
Mix whatever you decide to use with as little oil as possible.
Just enough so that it barely holds together (kinda like making a pie crust dough) . Then knead it together until its like putty. Then slowly add a touch of brush cleaner to it until it is thin enough to work with . You should be able to thin it down 3 to 5 times before you need to add more paste. Keep the mixed paste in a small jar and just pull out a little bit at a time when needed
Just enough so that it barely holds together (kinda like making a pie crust dough) . Then knead it together until its like putty. Then slowly add a touch of brush cleaner to it until it is thin enough to work with . You should be able to thin it down 3 to 5 times before you need to add more paste. Keep the mixed paste in a small jar and just pull out a little bit at a time when needed