Black limestone slabs

[Milou]

I'm completely baffled by the limestone I've had fitted in our front garden. The tilers have used every Lithofin product available then we spent ages talking to the supplier of Lithofin and applied more etc. We are left with a dusty light grey finish which looks horrendous, when we were promised flat black. Since the day the stuff was laid I've said we need something like Zebo (now Hotspot I think) sounds ridiculous as this is used for grates but the finish is perfect , can I use this, hope so, Milou

 

[matthewr]

nasty,,,has it been grouted or jointed ? if so was it before or after sealing of stone,and was the stone sealed before fixing? also whats the size and thickness of the limestone ?............and name

 

[Topshop]

I am not sure of the properties of the lithofin or the other products available in your area but if this stone is outdoors you need to find a UV stable product to seal it.

If the problem is efforvesence then the moisture from benieth the stone is wicking through and pulling the calcium from the stone. In that case a vapor barrier needs to be installed - basicly a total tear out and re-install.