Staining on edge of sandstone slabs

[loziv]

Hi

I am having sandstone slabs laid at the moment
And just noticed that around the edges of the slabs there is white staining around the edge see picture below

The slabs have been laid on full bed of cement and have yet to
Be pointed yet

What is causing this and how can it be rectified so I can mention to installer

Untitled

• loziv
• 26 May 2015
• 1

 

[r896neo]

It looks like mortar was spilt on them or pushed up between the flags from the bedding as the flag was tapped down and not cleaned off until it dried leaving a cement stain.


It will clean off with a little mortar acid. Always test on an inconspicuous area first for any reaction from the flag. If its sandstone it should be fine.

IF IT IS LIMESTONE ACID MUST NOT BE USED!!!!!!

If its not mortar stains it could be picture framing but it doesn't look like it.