I would try using a vinegar and water (50/50) spray on the stains.
Make a paste of baking soda and water, let it set at least 1/2 hour. Take a clean microfiber cloth and gently clean the stain off. You can repeat if needed.
Hi Ken, hope this helps you out,
Use of white vinegar is yet another remedy to remove stains that are resistant against mild liquid soaps. A solution that is prepared by mixing white vinegar is very effective for cleaning black kitchen sinks. Take a clean cloth and soak it in this solution. Use the soaked cloth to rub the stained area.
It is observed that stubborn water stains respond quite well to Lime-Away cleaner. One has to simply spray the cleaner in small amounts on the desired area and then use a clean cloth soaked in water to remove Lime-Away. One doesn’t have to really work hard to get rid of tough stains if one is using Lime-Away. This product certainly helps to restore the elegant appearance of black kitchen sinks.
A paste that is prepared by adding baking soda to water has also proved useful to eliminate stains from black kitchen sinks. Take this paste on a clean cloth and then rub it on the site that has developed stains. The paste can certainly help to erase the stains from the sink. One can also use mineral oil to clean black kitchen sinks. Put small amount of mineral oil on the stained area. Now, rub it using a clean cloth to remove the stains.
Perhaps this information will help:
I love my scrub daddy
Hi! Have you cleaning the spots with toothpaste? I know it sounds counterintuitive, but, I usually start with what the stain or spot is to loosen it. Toothpaste dries like concrete. A little toothpaste and warm water should loosen it enough to really clean it. Good luck and stay safe!
Hi Ken, Mix up a paste of baby powder and acetone and apply a thick layer on the toothpaste stain. Cover with plastic wrap. You can tape it down with painter's tape or masking tape. Leave for 24 hours, before removing the plastic wrap. Wait for the talc and acetone mixture to dry and harden before removing and then wipe down. Make sure to test in a small area first.
Here is some way to remove toothpaste stains. https://www.goodhousekeeping.com/uk/house-and-home/household-advice/a681124/how-to-remove-toothpaste-stains/#:~:text=Blot%20the%20area%20with%20a,to%20work%20in%20the%20detergent.
Fill with water and a little Wash soap. Let the water sink into the toothpaste and soften it. Then clean in the normal way.
here is some info Ken
Peroxide and baking soda paste
You can try to repaint it with tub paint if the stain does not come out
I cleaned my daughter's with rubbing alcohol and it works well.
Remove stubborn stains with isopropyl alcohol. Pour 1 tbsp. of alcohol directly onto a soft, absorbent cloth and wipe the stain away. No need to rinse -- the alcohol will evaporate, leaving a clean, sparkling surface behind.
Do not use abrasive cleansers, steel wool pads or hard-bristled brushes to clean acrylic sinks. Acrylic is lightweight and durable, but it does tend to scratch. Should a scratch occur, fill in the abrasion with a light layer of automotive paste wax and buff with a soft cloth until the damage is no longer visible.
Hi Ken: Use a mild liquid detergent and a soft cloth or sponge. The dark finish will mar and be damaged if any kind of abrasive cleaning detergents or scouring pads of any kind are used, so be very careful.
You can use bleach, but dilute it first and rinse thoroughly afterwards. You can also try alcohol and/or peroxide hydrogen.
Have you tried CLR?