I picked up some radio chatter between some of the It's-not-cast-iron-ers about a nifty piece of equipment used to clean steel & cast iron cookware. It's called The Ringer. It's basically a small washcloth made of stainless chainmail.
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I just got it yesterday, so I haven't tested it much, but so far it looks promising. It scrubs off any stuck matter, but not the seasoning. Amazon reviewers says it works awesome on glass dishes and other scratch-resistance pieces.
Since it is stainless, you can pop it in the dishwasher or just use soap and water to clean it.
The Ringer Cast Iron Cleaner XL 8x6 Inch Stainless Steel Chainmail
https://www.amazon.com/dp/B00FKBR1ZG/?tag=ihco-20