If the stain is old oil based substance e g grease it can melt and spread under the glaze creating a larger stain.
How to get rust stains out of ceramic plates.
It s a good idea to try the method on an inexpensive piece before attempting to clean valuable pieces.
Use as much table salt as needed to cover the stain in your enamel.
Cut a lemon in half and squeeze the juice over the salt to soak it into the stain.
Avoid soaps with scents and additives.
Finish up by rinsing the sink with clean water.
Continue squeezing lemon juice until you have covered all of the salt and made a paste over the stain.
Use a sponge to blend the powder into the water so that paste forms and allow it to sit for a few minutes.
To remove stains from the outside of a dish or cup make a paste with borax and lemon juice or vinegar and spread it liberally on the stain.
Bleach or chlorine may remove the stains but also can damage your ceramic item as illustrated below.
Use the sponge to gently scrub away the stains.
Get the sink wet with warm water and then sprinkle a small amount of the cleanser onto the stained areas.
Then you ll scrub one more time rinse off the baking soda paste mixture and dry the item.
I find the original dawn liquid soap works best.
Pour white vinegar directly onto the stain so that it s covered with a small puddle.
Afterward scrub the paste and rust with a toothbrush then let the paste sit for an hour or two.
Repeat steps 2 and 3 for.
Scrub salt and lemon juice into the stain.
Scrub the rust stain gently with the cleaning pad or sponge until the rust stain is removed.
Clean the pottery with warm water and soap.
Rinse the dish with warm water and repeat as necessary.
Never use chorine bleach.
Create a mixture of baking soda and vinegar until it creates a thick paste.
Empty the container when the stain is gone.
Use great care with any cleaning method.
Soap and water soak.
Run a sink full of warm soapy water and with a soft wash cloth clean the pottery.
If you have small rust stains a baking soda paste will work perfectly mix baking soda and water to form a paste and spread this paste over the rust.
Step 3 allow the area to soak for at least 10 minutes.
For dirt stains and caked on grime.
If the stain is on the edge and cannot be soaked this way soak a cloth or sponge in white vinegar and set it on the stain.
After you have the piece as clean as you can wash it with soap and warm water to clean off and residue of the peroxide.