Restoring black tiles

[Prenton]

Hi
My daughter has black slate tiles on her patio, they have become grey and stained with a white residue, I have tried pressure washing and scrubbing etc but no change. What product would restore them back to black please

Thanks

Peter

 

[Prenton]

Hi
Has any one any recommendations on how to get them back to black and then seal them please

 

[ltppebbs]

You could try Ltp Back to black, this is a black colour restorer that is breathable.
patio would need a good clean with Ltp Grimex first to condition the stone first
They do 100ml samples to try it out too.
website shows videos b4 and after use and guides.