I've had a patio laid using black limestone flags.

The builder grouted using sand & cement and then washed it off using brick acid. He didn't seal them before he grouted or washed off.

The flags are obviously porous and so the grout/water soaked into the flags. They are now light grey.

I've tried various products to try and restore them to black but failed.

When they are wet they look fine, black.

I'm gutted, are they ruined or is there something that can be done ?

oh no not another one. Have you got any pics you can post up?

Hello and welcome..

I wish builders would read up on what they are going to use..

A colour enhancer might work but i would be contacting the builder first and ask him what he is going to do to rectify it.. and don't let him fob you off that it was the correct method..

Brick acid on limestone can we see some pictures please.

Hi, I have the same issue. After my contractor cleaned the patio with brick cement, my patio is now light grey and the surface appears very granular. The contractor assures me that further treatments can be appield to rectify the issue but I am not convinced.

Any advice on how I deal with this would be appreciated. Photographs attached.
Snow November 2010 058.jpgSnow November 2010 059.jpgSnow November 2010 063.jpg

hi i think it what we call stuffed you will be lucky to restore that and it will prob be cheaper to remove and re do
sorry not the news you wanted
(one day people will realize builders build and tilers tile )

I would try this...Tradetiler.com the forum sponsor sells it.
Grout Haze Clean-Up from Aqua Mix

AQUA MIX GROUT HAZE CLEAN-UP is a safe and effective concentrated cleaner that is added to the final bucket of grout cleanup water for removal of cementitious grout haze and latex additive film from tile during the grout cleanup process.

It may also be used full-strength to remove light grout residue within the first 10 days after grouting.
Use on:

• unpolished natural stone (such as granite, limestone, marble, slate, and travertine)
• polished granite and slate
• ceramic
• porcelain
• quarry
• saltillo
• terra cotta
• cement pavers
• masonry surfaces
• other stone and tile surfaces

TEST A SMALL AREA:

According to application instructions to determine desired results.
APPLICATION:





DURING GROUT CLEANUP:

1) Read entire label before using.
2) Perform grout cleanup per grout manufacturer’s instructions.
3) During final grout cleanup rinse, mix a minimum of 3 ounces (90 ml) of Grout Haze Clean-Up per gallon (3.785 L) of water.
4) Wet a grout sponge or terry cloth towel with the cleaning solution, wring out excess liquid.
5) Wipe diagonally across the tile.
6) Repeat steps 4 and 5 every 10 to 15 sq. ft. (.9 m2 to 1.3 m2) or as necessary.
7) Remove residual cleaning solution using a clean grout sponge or terry cloth towel dampened with clean water only.
AFTER GROUT CLEANUP - WITHIN 10 DAYS OF GROUTING:

1) Use full-strength if grout haze was not completely removed during grout cleanup.
2) Apply directly to surface and agitate with white nylon scrub pad or brush.
3) Allow product to dwell for 5 to 10 minutes for stubborn areas or heavier grout residue.
4) Rinse with clean water to remove residual cleaning solution.

Oh dear that is a sad old sorry state! I think that is past any chemicals help to restore it and the colour intensifier would only bring out the colours you can se even more so. its either a remove and re-do or a full regrind and bring it back that way. bad news not what you want to here.