Most of the sites I've found on the internet recommend Deco Art for buying glass-staining paint. They sell specialised paint for use on glass, both transparent and pearlescent, as well as an opaque variety to use for leading. Unfortunately their website (or at least the page I linked to, listing their products) doesn't give a great deal of detail on what kinds of paint these are or what's in them.
However, this site tells us more about the makeup of glass paint:
What exactly is glass paint?
- Often called enamels or vitreous enamels, they are a mixture of metallic oxide pigments, flux and ground glass.
- They are used for surface decoration, and are fired on permanently in a kiln.
- Their colour and opacity depends on the type of metal oxide used.
They also discuss the difference between opaque and transparent paint, but that's less relevant to you since you only want the transparent kind.
For the leading, what's traditionally used
is lead came
, thin soft metal strips which can be fixed onto the glass. You can find detailed instructions here
on how to use lead came
. Alternatively, you can just use a different kind of paint, which is essentially glass-staining paint of the same kind as above except opaque and in a black or dark grey colour: