I tried HCI and it's not doing anything. Left it on for 20 mins, came back and scrubbed and scrubbed...not a single dent.
Strange part is it fizzles at the seams where the grout is but nothing happens when i pour the hydrochloric acid on the (what appears to be) mortar on the title. Is it even mortar? How can i get it off??

I cant scrape and chip off because its very thin at a lot of places.





Moderator note: member from Indonesia.

 

Welcome to the forums.
You should put non-US in your bio as it helps to clear up language barriers.

Title ?? Do you mean tile ?
It doesn't look like tile in the picture. It looks like painted cement or painted block.
That may even be a parge coating over block.
Where is this ?

 

Are you trying to remove the mortar or the paint?

 

I'm trying to remove the grey stuff on the green surface.

The green surface is porcelain'ish (just like tile is) so I assume it's tile, of some sort.

 

If you don't mind mod, could you change title to tile. It's auto correct thinking it knows what I want to say more than I do.

 

I agree.
It appears to be paint on a parged or cement based plaster.
Take a sharp scraper and see if the green flakes off.

That surface looks exactly like how some walk-in coolers from the siixties and older were finished.
It can be painted but it needs a paint that can breathe.......not a modern gloss or semi-gloss finish that will trap mosture.

 

I would try the muriatic (hydrochloric) acid again. I suit up in protective clothing and use a stiff bristle plastic brush to scrub the mortar with the acid solution. Just pouring acid on it doesn't work very well but if you scrub you should have much better results.

 

Pilot... I've ready done that and nothing happens.

 

Anyone?? PLEASE! I don't know what to do. Just tried scraping it off. It's nice at thick parts, but the parts where its thin is just not practical.

 

If it fizzes or makes muriatic acid turn yellow then the acid is working. You just need to scrub thoroughly with a brush while applying the acid.

 

Pilot...
That's the thing though. It DOESN'T fizzle. It fizzles only fizzles at the seams where the grout is. Makes me wonder if it is actually mortar/cement. It looks like it though. Maybe it's some kind of plaster/adhesive?

 

If the acid does not fizz or turn yellow then whatever that stuff is it is not made with Portland cement (thinset, mortar or concrete). It's probably a adhesive of some type. Try a solvent like MEK, lacquer thinner or acetone and see if one of them will touch it.

 

Got some tile installers to come look at it. They confirmed it is cement. They chipped/scraped it to show me. They said it is not coming off with HCI because it's been there too long. But then the seams have been there just as long and the HCI works on those parts immediately.

They said I could only get it off using sand paper at 310 grit. I asked them if that would scratch the tiles and they said yes... it's unavoidable. But I don't want the tiles scratched, obviously. So I asked if the scratches could then be buffed out/polished. They said that it would not be possible to do so because it's not ceramic or its variant. That defeats the purpose... getting an ugly site off and replacing it with another ugly site.

So now I don't know what to do. Replacing 5 stories of tiling is too cost prohibitive for me. Especially for something I feel there has to be a remedy for. There has to be something out there that works on this stuff like HCI does on cement. But then, this stuff IS cement, looks and feels like it, and was confirmed to be it by people who work with it all the time.

​​​​​​This is driving me crazy!
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I think you are right. The acid is attacking the thinset or grout that's between the tiles. Have you tried stronger concentrations of acid?

How big an area do you need to clean? If it's just the area in the photo you could use a strong acid solution and scraping and chipping. If it's the whole building then you need to consider replacing the tile.

 

What is a stronger acid? I've already done undiluted HCI.

 

WOW! Straight muriatic (hydrochloric) is as strong as you can commonly buy. There are probably slightly stronger laboratory grades but it's not going to be a big difference.

 

You said the tile expert said it was "cement" but they may not have explained it properly.
If that skim coat or parging was done in the last 50 years it is probably not totally cement based which is the only thing acid will touch.
If there is any synthetic component, waterproofing or even coloring in the mix it could be immune to acid, no matter how strong.

I know it would be frustrating to think you have an nice expensive tile only fractions of an inch from the surface but unfortunately it is likely not feasible to recover.
You also need to consider that the tile was coated for a reason and if you did remove whatever is on it you could be faced with a bigger task of fixing the tile than the effort it took to expose it.

Just out of curiosity, is this a multi-story apartment building?

 

[/img][/img]Yes it is Greg. Could it be hard water stain?

 

This area is a bit different than what you orginally shown us.
It almost looks like someone may have tried to re-do the grouting and made a mess instead.
If that haze is grout sitting on top of good tile there could be some hope of cleaning it up but if it damaged the surface nothing will make it look new.

In my case I hired a family member to help paint and clean up our current home and without knowing better used muriatic acid in two toilet bowls and a dishwasher to clean up the scale.
It etched into the suface of the bowls and stripped the paint from the interior of the dishwasher.
Something simiar may have happeded to your tiles.

The first pics showed a thick layer of what looks like some type of parging.
Those stairs are not as bad.
Maybe a mild polishing compound and an electric buffer with a lambswool pad would clean it up.

 

Sandpaper is having a hard time, I don't see how lambswool pad would do anything