On Facebook -JOIN I Antique Online.com: Collectors of Antiques and Collectibles.
Here is the link for the group https://www.facebook.com/groups/327133184409134/
Please join our FB group where YOU can post directly.
A Community For People Who Buy, Sell or Collect Antiques, Collectibles and Art
This is usually a popular topic. I've seen these discussions at other boards. The PyrexLove website has a great article on this topic. Perhaps member Linda Y., from PyrexLove, can provide us with a link to it. Corning Cleaner, Mr. Clean Magic Erasers, Dawn heavy duty spray, and oven cleaner are a few popular products used for cleaning burned on grime.
My personal favorite method for restoring slightly faded Pyrex colors was given to me by a customer, soon after moving to Florida in 2002. It does not work on every faded piece, though. But it is simple and easy, and always worth trying. Treat the painted surface of the piece with cooking or mineral oil (any food safe oil will work), allow the the piece to sit with the oil for a few hours or better yet overnight, then wash by hand with mild dishwasing detergent. Do not use the dishwasher again.
Barbara always advises hand washing for vintage kitchen glass. I do ocassionally cheat, especially with my Pyrex RW and use the dishwasher.