Question about cleaning black varnish off pots (and why corning pots are brown)?

Yes. It is called "lye". Easy Off oven cleaner is lye.

Scrubbing is about useless. I'd try oven cleaner first,then perhaps an acid.

The brown pot is Visionware. Corning stopped making it years ago because it is crap to cook with. I don't know if it is colored for visual effect or the compound to take the heat. My wife had a visionware pot and it went into the trash with the burnt on the bottom potatoes that stuck while boiling with water.

Treat your wife to a good quality pot. There are many, like AllClad Farberware etc. Multi-layer material that give really good heat distribution.

WTF? Even deep frying shouldn't put that much grease on the outside of a pot. I'm surprised you didn't have a fire.

When my husband blew off the seasoning on my cast iron frying pan by using it on a turkey fryer burner, I got him his own pan. Perhaps you should get your own deep-frying pan.

Fashion. Plus, as you see, grease and scratches show up less. Cindy Hamilton

Corning stopped selling them in the US very roughly 20 years ago, but brought them back very roughly five.

So yes, they are available again.

(The Corning line of cooking ware, plus, of course, Corelle, is now owned and marketed by World Kitchen)

The question is, Why? Worst cookware available.

I have used Sokoff to remove heavy deposits on a commercial waffle iron. It works well and is safe on both aluminum and stainless steel.