0mole1 11 years ago Ive had good luck getting the black off pyrex using baking soda (dry) on a damp sponge.... kind of like using cleanser. Put a table spoon of soda on the counter, dip your well wrung out sponge into it. Then rub hard on the black stuff. You don't want to dissolve the soda... you want a kind of dry-ish sludge. It's 'gritty' enough to kind of knock or scrape off the burned stuff, but doesn't scratch the glass. Enamel is a kind of glass.