Doodledog
I now realise you were asking about products, rather than gizmos
Barkeepers Friend is like magic dust. It's similar to Vim/Ajax but it doesn't scratch. My old cast-iron bath came up very well with a good sprinkle of that and a go with the scrubber. I have a very recently installed new one now, which hasn't needed industrial strength treatment. I'm told it needs diluted washing up liquid to keep it looking good, but time will tell.
Perhaps the mineral level in the water - we have to use vinegar. Washing up liquid would be my choice. Alas, vinegar is needed.




