How do I clean the brown (grease? burn?) stains from the bottom of a porcelain baking dish?
Soaking in soapy water doesn't seem to help.
Best Answer
You can't, mostly if it is unglazed/porous
(most) Porcelain dishes have porous bottoms, anything that touches it will be sucked in the small pores, and if baked in, will be more difficult to remove.
If the glazed part of the dish is clean, I would not think much about the bottom.
Some people will see it as a good sign that you are using it.
On the other hand, you could try using products like Bar Keepers and a plastic scouring pad to clean it.
Anecdotal, I keep the glazed part as clean as possible, and don't really care about the unglazed bottom.
From the pictures (thanks for adding) it looks like sediment from the water (source, pipes, etc) and CLR cleans it easily. Just don't breath the fumes.
Also, you can try commercial coffee pot cleaners such as http://www.urnex.com/ to remove the build up.
Finally, if none of the above is available in your area, try Vinegar first. If that didn't work, wash off and switch to baking soda. you may have to make a paste and let it treat for a while.
There is also this recipe for cleaning rust stains from aluminum pots, though I haven't tried it.
Many rice cookers use an aluminum disk as the heat transfer element. Aluminum discolors easily, but it's also soft and subject to scratching. Scratches will reduce contact between the heating element and your cookpot.
Unless the stains form actual bumps on the surface of the element, you're better off leaving them alone.
Best Answer
You can't, mostly if it is unglazed/porous
(most) Porcelain dishes have porous bottoms, anything that touches it will be sucked in the small pores, and if baked in, will be more difficult to remove.
If the glazed part of the dish is clean, I would not think much about the bottom.
Some people will see it as a good sign that you are using it.
On the other hand, you could try using products like Bar Keepers and a plastic scouring pad to clean it.
Anecdotal, I keep the glazed part as clean as possible, and don't really care about the unglazed bottom.