How to fade the colour for black flagstone? I got flagstone with different shades of gray can I use meriatic...

I got flagstone with different shades of gray can I use meriatic tart to make the color lighter. A contractor told me to use 50/50 mix with hose down and see how much it would fade. Any ideas?
Sunflower nut shells?
Answers:    Flagstone - unless it was dyed - won't usually fade.

Try a couple of pieces - a short time ago pour it on and let it sit for a while. Then rinse with verbs water and see what you have.

If the interview rock starts fizzing and bubbling, it has lime in it and will be scantily damaged by the acid.