Strong enough to remove rust and stains from marble; if there are stubborn stains, it requires several applications and scrubbing

It is effective. Pay attention to the instructions for use because otherwise, along with the stain, it is capable of removing the tile as well. It removes grout, marks from flower pots, etc.

In a marble sink and kitchen countertops, it did almost nothing. It left a slight whitish residue and after use, if I leave a plate or glass, it appears as a mark. For me, it is not worth it.

I have a stain from red wine on my mosaic tile and it didn't do anything by following the instructions, so it doesn't work for mosaic tiles!!

It needs a test first in an area that is not so visible initially, perhaps diluted. I put it in a sprayer and it foamed during application, I left it for 2-3 minutes and wiped it with a hand brush. All this on dry marble. It does a very good job, it releases fumes so be careful in closed spaces. Also, at the end, a very good rinse in combination with light scrubbing to remove any residues. Specifically, brown salt stains on marble, due to daily watering of the lawn for over 10 years, were cleaned with the first application. There was very little left but I ran out of cleaner, I will buy it again to clean it completely.

I got it as a test for marble surfaces and mosaics.
It left marks on the marble that don't come off at all...
I didn't even try it on the mosaic... Unacceptable!