Black Limestone - Cement stain removal

[Peter Knight]

Hello

I have laid black limestone :-( and now have quite bad cement staining. I power washed it which I think has made things worse! Images below.

I have not yet done the jointing and on reading this forum know that I need to seal the flags before jointing. However, first I need to remove the cement stains.

I have chatted to a company and the advice is:

1. Wet area thoroughly.
2. Miracle Heavy Duty Cleaner (Acid Substitute), Mild pH Cleaner - applied with an industrial scrubber fitted with solution tank and brush.
3. PSRP Honing powder 220 grit - applied to surface and worked with the industrial scrubber fitted with a brush.
4. Wet Vacuum.

Just interested to know if anyone has any comments on the above plan?

Pete

 

[Dumbo]

We have a specialist on @Lithofin BOB . Hopefully he will pick this up . Trust him over everybody.

 

[Lithofin BOB]

The cleaner states to " non acidically "break grout films. grouts contain polymer binders which can be broken by using an alkaline cleaner although still very difficult on textured stone. This is cement!
The cleaner can be tested, it will hopefully remove some contamination but I think generally greases and grimes .

I would test the cleaner on an un laid- un stained tile first to confirm suitability. Always check this

I only worked with powders on flatter surfaces with pads, again test on a unlaid large tile and be confident to move onto the floor once you have mastered the spare. My worry is that the cement is filling larger voids and capillaries which are then only to be flattened but remain in the capillaries showing white. It will be dependant on how aggressive a hone/cut into the stone you get, sure @ats on here discussed carborundum brushes one time and these may give a deeper cut and follow the contours of the face ,if required.

Test away, if you have to invest a lot, might be easier ,quicker and cheaper to replace the contaminated stones before you point them. Powder can be quite an art to get the balance right if inexperienced .

 

[Peter Knight]

Thank you for the advice. I will have a go! You mention breaking down with an Alkaline cleaner. Would it be better to use the following instead?

PSRP X-treme - Heavy Duty Cleaner (fast acting concentrated high alkaline cleaner)

Or use one followed by the other as a separate application once the first has been fully washed away?

 

[Lithofin BOB]

As above, alkaline cleaners will generally deal with greases and dirt, you will only need to test one product. Then deal with the remaining cementisiouse contamination .
I like the sound of the first cleaner to test -as it states, acid substitute and will deal possibly with the residues you have.

 

[Nicola]

How did the cleaning go, our black limestone (newly laid) is looking similar!!!

 

[Tile Fix Direct]

Bob from Lithofin is the expert with many years experience, follow his advice to the letter, and use Lithofin products!
Lithofin Tile Cleaning | Lithofin Tile Sealing | Tile Cleaner | Tile Sealer - https://www.tilefixdirect.com/category/lithofin

 

[Time's Ran Out]

I’ve yet to see a Black limestone floor outside laid successfully!
There was hundreds of comments on other sites and here on the same subject - cleaning cement!
No help but they should be sealed BEFORE laying.

 

[Paul Munro]

I had some success with lemon juice and fine grade wire wool. My staining was dust and detritus from cutting...... Then it rained and I dint persevere with cleaning.

Scrub the limestone with wire wool and lemon juice then wash off straight away. Brought mine up nice and deep black again.