Slate will do that if it wasn't sealed properly. We use seal and enhance on slate floors. I'd have a stone restoration company like this company below come in and professionally clean and then use seal and enhance sealer. Slate isn't the best choice for a shower. Regardless you have to keep up on the sealing (every 6 months or so). https://www.nsmarble.com/

When looking at the pics the overall orientation of the stains tend to be parallel with the walls. It's as if water hits the wall and runs down onto the floor, wondering if it's related to the wall grout. Maybe the walls were not properly cleaned or the wall grout is not properly cured and it is being deposited on the floor. Most grouts contain polymer additives which can be really tough to remove if not done immediately upon grouting, especially some of those newer stain resistant ones.

Ahh, sorry, missed that. Do you have calcium, iron, excess of other materials in your water?

Good point about the water, is the water in your region extremely hard? It could be calcium deposits, they show up as white and would be highly visible on a black tile. Try cleaning with some vinegar, it that removes it then that's likely the problem.

>>following...

"I did use baking soda at one point"

Baking soda is not likely to work, also it is a white type of powder so when it dries it can also leave a white residue. You could try say CLR instead of vinegar but you need to be careful as you do not want to chemically etch the tiles surface. Even with vinegar, do not leave it on for an extended period of time, just dampen a cloth and rub then rinse. Might need to do it several times.

I had the same thing with a shower with similar color tile, and it was due to deposition of minerals from the water.

Baking soda used with vinegar. Make a paste and apply it and let it sit for about 15 minutes. When you rinse it off, use a scrubbing brush. If that doesn't work, I have found a cleaning agent that specifically removes hard water spots and mineral deposits.It is called Bio-Clean Hard Water Stain Remover. I bought it a Amazon, but it is not cheap. I think I paid $24.95 for a 40 oz. bottle, but it doesn't take very much. It will also work on glass shower doors. "It cleans and seals, lasts up to 3 months," according to the manufacturer. Not affiliated, just a satisfied customer.

this is a ceramic tile? it almost looks like the glaze has been scrubbed off of it. what is the brand/type of tile? hard water deposits are more random. this almost has a pattern to it on every single tile.

If it's looked like this since day two, it's NOT hard water deposits.

It could be efflorescence.

how long has it been installed? HOW was it installed on the shower floor? any pics?

what did it look like brand new?

why would the installer 'seal' ceramic tile?

If he applied a sealer to this tile and let it dry, you've prob got discoloration from the sealer. a sealer that doesn't get absorbed (and of course it wouldn't since it's ceramic) will discolor if it's not wiped off the top. have no idea what he did or what he used. Since it's been like this from day 2, I'm betting it's something he did or defective tile.

need more info

Beth has brought up some interesting points! Her points seem to be right on track ...

There are slate-look porcelain tiles that have a matte finish that have precisely that appearance. I don't think there is anything necessarily wrong with the tile other than mineral deposits.

except you don't get mineral deposits in two days. she said it looked like that 2 days after install. No way. The installer did something to the tiles either by incorrect install, incorrect sealant application or defective tile.

I asked about application because efflorescence is a big possibility. if moisture was trapped underneath and never had a chance to cure, that would cause the white appearance.

I have hard water. it takes more than two days for deposits to build up to that extent. AND, it would never look so uniform. some tiles would have it, some wouldn't. You also get heavier buildup in the corners and joint lines of the wall/floor. and the grout would also discolor.

OP, can you please show us a picture of what the tile looks like out of the box? Have any extra pieces?

Here is pic of shower along with larger floor tiles. Please note the only difference is size of tiLe. I have cleaned with vinega, baking soda, CLR for calcium removal and Dawn dish soap, just because it’s pretty efficient for many different thing. And yes, this tile has no shine along with lighter grey streaks for a slate type look. Sorry no extra tiles available

Maybe the best long term solution not just for this space but overall is a good water softener I certainly would not want to have get down and clean the shower floor everytime you use it.

Look into a color enhanced sealer.

Intensifia from Dry Treat should solve the problem

https://www.drytreat.com/sealers/residential/stain-proof.html

Precision granite,,,,it's a ceramic tile. enhanced sealers need to absorb. Most ceramic tile isn't porous enough to accept an enhancing sealer.

Linda, it's possible that particular tile isn't meant for constant water usage. Or, somehow all that cleaning may have damaged the glazing on the tile.

years ago I installed some nice tile from Walker Zanger. It was a glazed ceramic. after about 6 months to a year, I noticed the tile (inside my shower on the walls) became very dull looking. I called the company and found out that they recalled that tile as it wasn't suitable for wet areas. The crazing (minute fissures in the glazing on the tile) allowed for water to absorb and eventually dull the glazing.

They paid for new tile and new install.

So, show your pictures to the tile company and have them contact the manufacturer. You may have the same issue that I had.

Linda-

Bear in mind that having "new tiles installed" on only the floor can be problematic. In the process of removing those tiles, the waterproofing could be damaged at the perimeter where the walls and floor intersect, and you could end up with a leaking shower as a result. I hope you find a resolution that doesn't require the expense, hassle, and potential problems of a re-tile.

@ Beth H - only half read that it's a slate LOOK - not actual. My mistake.

I'm going to look like a shill for this company because I posted this same info on two other threads, but I really have no connection to them other than being extremely pleased with their product. I was sick about the water/mineral stains on a new sink as well as the metal and metal look plastic on my Hansgrohe shower fixtures. I tried everything and this stuff is a miracle. My window washer uses it to remove water spots, too.

Try this...it's taken water spots off every single thing I've ever
tried it on, it's non toxic, non abrasive. You can sometimes get free
samples at Ace Hardware if there is one near you. There are other
products called Bio-Clean, be sure you get THIS one:

I have only used the cream in this container, can't vouch for the liquid.

https://www.bio-cleanproducts.com

That is the same product I posted in an earlier post. If you buy it on their website it is more expensive than at Amazon.

I didn't notice that Nancy, but two satisfied customers to recommend it! You can buy it at Ace, too, if you have one near.

I do not see a particular problem in the picture, but these tiles are always the same.

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