I was going to suggest mineral spirits or paint thinner. This link seems to suggest the same: https://www.doityourself.com/stry/how-to-remove-adhesive-from-ceramic-tile

I don’t think it’s glue, as it’s not sticky. At this point I’ll try anything though. I have a few extra pieces of tile I can test this on before I do it on the actual floor tiles, so that’s helpful.

Yep...residue transfer. What is the residue? Who knows. The question becomes, do you REALLY want to tackle/pay for the removal of individual tiles to get rid of the problem?

You obviously have enough tile to do this. The floor has been grouted so they are done. Whether you remove/replace them today or next year, it won't matter. You are disturbing a finished tile floor.

So....you might as well give the mineral spirits, rubbing alcohol, goof off, muriatic acid stuff a try. There is no harm to the tile by doing it. And it gives you some understanding of what you will have to do/pay for to get the tiles all nice an pretty. If the cleaning doesn't do anything, then you know you need to replace the tile to get rid of the problem. Whether you do that today or 365 "todays" later, it won't matter. The price is the price.

Personally I'm a cheap and lazy house dweller. I like to see if I can "live with it" - which is free. If I can't, then I try the cleaning fix. If that doesn't work, then I pay to have a professional nip in and deal with it. Pay the bill and move on.

Good luck. Try the cleaning routine out on some extra tiles before moving the method to the floors. Good luck. Let us know what works (if anything).

The white marks may have come from the water they were submerged in not necessarily the tile itself. Maybe try CLR on one of your spare tiles or google other solutions for hard water marks on surfaces. The white pattern on the bottom of the tile suggests that it may have formed after the floodwater dried on them.

I'm looking at this from a completely different perspective. Another possibility is it appears you have a porcelain glazed tile this could simply be poor glazing showing through and not a topical substance at all. You must consider box store quality or lack there of. It could be the white was applied to the backs to prevent adhering to each other during manufacturing. Applied to soon it's embedded in the glaze of the tile below. This should have been noticed during installation and not installed. You set the tile, you clean the tile then move on. Of course we are doing forensics from a photo so anything is possible. Porcelain tile that meets U.S. standards will have less than .5% absorption. Key words U.S. standards

My photo forensics say who the heck butted up tiles without grout? That’s a redo.

You can see the grout in the second picture. It’s only about a 1/16 inch grout line. It’s rectified tile on a leveled concrete foundation so my contractor told me he could make the grout lines very small.

I soaked a sponge in some vinegar last night and placed it on one of the test tiles. I let it sit with the vinegar on it for about ten minutes, then lightly scrubbed it off. It didn’t come back when the tile dried. My concern now is that I can’t really clean the grout with vinegar, so I’ll either have to find something else or just be extra careful. Luckily it’s only on about 10 tiles total in the entire house.

Thanks for the suggestions!

While doing a deep-dive through a Q&A for my specific brand of tile, I found that another customer had asked the same question and this was the manufacturer response:

”Hi, Thank you for your question regarding our 8x48 Natural Timber porcelain tile. When the tile goes through the kiln, we (like all tile manufacturers) place a solution on the bottom of the tile to ensure the tile does not bake/stick to the conveyor belt. Once the tile is fired, that solution becomes a white powder that should just brush off as you pull the tile out of the master carton. There is no adhering agent, but maybe there has been some humidity along the way and it is not just falling off. Using some non-abrasive cleaning solution (water mixed with some vinegar would be fine) and some "elbow grease" will remove the white color.”

I guess that answers that!

Ryan, I was going to suggest a grout haze remover or one of the other products that is safe for tiles. You may not have to scrub as hard as you would w/the vinegar.

And the reason that you don’t have grout in much of that shown is so that dirt and crud can get in there?

Minimum grout joint width allowed 1/16" and depth of 2/3's tile thickness. They look butted to me in the photo also. Hopefully not.

Once you get rid of that white stuff, the maintenance of the tile should be simple mopping... not what you are doing now... Glad something is working!

Hi Sophie, I think we’re talking about two different pictures. The only tiles grouted are the ones in the second photo. You can see the chestnut-colored grout. The other pictures are just examples I took before the installation and grouting were finished to show the weird white marks on the tile. He goes back and cleans the thinset out of the grout lines and then vacuums before grouting.

My contractor was very highly rated from multiple local residents and came recommended from a couple other contractors I had doing various jobs around my house. He’s got 35 years of experience. I’m really hoping I can trust him to do the right thing. He’s been very professional and meticulous throughout the project. Fingers crossed!

I know this is from two years ago But what was the solution?

I have the same issue. Did you resolve it. I’ve tried everything