When I built my pool in 2007 my natural stone coping was a beautiful black colour with brown and beige veins running through it. Over the years with the sun and I guess salt water the colour has turned to a dull cement looking grey and I have lost all the character of the veins also. The only time it looks good is when it is wet, last year I tried applying an impregnator from Techniseal and it looked better than new but only for a bout 2 to 3 weeks and then it looked even worse than it did before.
Is there anything I can do to get the colour and character back?
Thanks for your help