Grout Haze on Slate Tile

[DCR]

We laid slate tile on our lanai. Since we are new at this, we did not seal the tile before grouting. We did get the grout up out of the small indentations but cannot get the haze off of the tile. If we put a glossy/wet looking sealer on the tile will that help? I read that vinegar will help get it off. Will vinegar damage the slate?

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[doitright]

Hi DCR, Welcome! :)

First names are good around here! :shades:

As far as your slate, you can TEST with vinegar and water. Start with 2 parts water to 1 part vinegar. If not successful, try 1 to 1.

[diego79]

If we put a glossy/wet looking sealer on the tile will that help?

Nope


I read that vinegar will help get it off. Will vinegar damage the slate?

To remove grout haze you need one of two things. Acidic cleaners (like vinegar) and other acid based tile cleaners will remove grout haze or a stone specific grout haze remove made for stone.

With stone you don't really know how the stone will react to the acid wash. I had a customer recently who said the contractors acid washed the slate and it brought out some rust stains. (their slate was high in iron)

If you are going the acid route, test, test, test a small area. Better yet, search for a HMK stone haze remover product online and it should work.

[Davestone]

I agree, but an enhancing sealer will help, as long as the grout isn't a real stark difference in color to the tile. :bow:

[gedwyn]

Hi,
I have the exact same problem. I put slate down without sealing brfore I grouted. I never would have guessed but yes the slate is very pourous.
I have a haze as well and even some in the indentions. I have washed it several times with water to no avail. Did you ever get yours off? Several people told me to let it cure before I use acid. I just did it yesterday.

Anyway did you ever get it off? What did you use?

My wife is not happy with me so....

Thanks in advance :sick:

Paul

[doitright]

Hi Paul, Welcome! :)

Can you post a picture? :shades:

If the majority of the problem is in the clefting, I would try to remove ASAP. Start with a rigid putty knife, or hard piece of wood, etc. You need something that won't be prone to scratch the slate if you slip. If you're more careful you can use a stiff putty knife, a three in one tool (painters putty knife with triangle at one end of a stiff blade and semi circle on one side), or even a utility knife.

This is painstaking work, with no easy remedy except patience and perseverance. Most acids won't remove the big stuff, so it's best to try to remove the bulk of it ahead of time.

[gedwyn]

Thanks for the quick response. I am attaching a couple of pics. To be honest I am more concerned with the haze than the grout in the nooks on the slate (Although I would like to lessen it a bit).

I have not tried Vinegar yet. I tried muriatic on one peice and it seemed to really work but I would rather use it last if possible.

I have some aqua rite phosphuric acid but am holding off on that as well. It has been 1 day since I grouted. I can not bear the thought of a rip out. Any advice would be great.

I guess I should have paid somebody in the first place.

Would my pressure cleaner help? It is outside so I do have the freedom of hosing it off.

Hope the pics help

Thanks,
Paul

[doitright]

Hi Paul :)

Please don't use muriatic acid for anything! The Aqua Mix Phosphoric Acid is the way to go. It is also much safer. I would let the grout cure for a few more days before any type of acid washing.

Most importantly, TEST first.

[gedwyn]

Just an update. I have washed the tile with vinegar (3 parts to 1 water) twice
and hosed it with water real good and it has made a huge difference from what it was. The thick grout in the nooks and crannys have lightend up as well with a wire brush. One more time and it should be back.

The tile does seem a tad lighter though. Maybe it is just me. But it is looking much better.

Glad I used the vinegar first instead of jumping to phosphuric acid.

Thanks for the tips everyone.

One more question. Should I seal the tile as well? It is outside lanai tile so should I seal it?