Victoria
Hi Vicky
February's issue of Crafts Beautiful has an item showing painting on
drinking glasses. They recommend pebeo glass paints (www.pebeo.com) and say
that the design can be washed off at any time until the glasses are baked in
the oven. While they don't give any instructions for the baking, they do
say that you should "carefully follow the manufacturer's instructions when
baking paints in an oven".
I've only ever done decorative glass painting, using glass paints (sorry, I
don't have them any more and can't remember the manufacturer), and they are
generally translucent - I would expect ceramic paints to be slightly more
solid so not give quite the same effect on the glass. It might be worth
just having a 'test' glass so that you can experiment and see what you/your
children like best.
Hope this helps (a little!)
Julie
Victoria