i used a matt black car paint in a normal spraycan. ( hycote , cheap as chips budget car paint ).
as for any paint that needs to adhere to glass , you must add light coats , stopping for 15 minutes between each coat.
this will gradually build up the paint and the layer . make sure the glass is completely clean , i.e - no water marks or smudges / fingerprints.
take your time and have the glass masked correctly with tape beforehand.
and lastly, do not use a gloss car paint on glass . your asking for trouble if you do.