QUESTION

I recently completed an installation of an unglazed porcelain charcoal penny tile in our kitchen. It wasn’t until after applying the contrasting white grout (Mapei Ultracolor) that I stumbled upon an article letting me know I should’ve prepped with grout release first. I’ve gotten the haze up quite easily, but I’m left with small sections of white grout in the pores of the tiles. (Photos attached)
Unless I’m doing it incorrectly, warm water and vinegar are not helping and I’ve tried both Miracle Sealant’s Heavy Duty Acidic Cleaner and Mapei’s Epoxy Grout Remover (I read it could be a stronger option) with no effect.
Is there any hope for removing these stains or am I doomed to be reminded of my research oversight forever?
Photos: https://photos.app.goo.gl/82aBiQ8WmKquMyEq9

ANSWER

ANSWER - The grout that you used may be a polymer modified grout similar to a grout with a latex additive.   Acids won't attack the polymer, but there are products for removing latex haze.  Try a latex haze remove.  Make sure you let a wet solution stay on the tile for about 5 to 10 minutes.  Use a scrub brush with bristle brushes and scrub it with some effort without scratching the tile.  Then pick up dirty water with a wet vacuum and rinse and see if that helps.

I have also seen cases on unglazed porcelain tiles where a detergent cleaner with silica sand is used with a buffer scrubber to remove difficult hazes.

Whatever you do make sure you test it out first to make sure it will have a satisfactory outcome before doing the entire floor..

After the tile floor is cleaned to your satisfaction and dry, the apply a penetrating sealer.  Make sure you use lint free cloths and that you immediately wipe off the excess sealer with a dry lint free cloth after you apply the sealer.