This bowl was heavily stained and a mess after being outside and full of fuel for over 43 years.
Used "glass stain and water spot remover"
Do you know what dissolves the varnish left over from old style fuel? Ethanol gas. Old fuel won't dissolve it's residue but ethanol fuel does.
Gee, can you still get that stuff? I notice the old "Coast to Coast Hardware" tag on it, so you've had it a "while."
Might be good stuff to clean headlight lenses?
ammonia water cuts resins left by gasoline and kerosine. Use full or cut with water. I clean out old kerosine lamps with this. Cheap and works great.
You can use steel wool on glass.
Get a can of this and the grime and old fuel residue will melt right off.
SOS or Brillo pad will do wonders.
carb cleaner and steel wool + elbow grease
Get some 5/0 steel wool or try oven cleaner.
What about soaking in CLR?