For several years we have been laying travertine on the patio. Slowly and slowly the ugly darkening has set in. The stone is cleaned 2 times a year with neutral soap and water – but I think the dirt has settled in small pores or depressions. I know you can't use harsh products on travertine, which is limestone. But what can I do?
Or should I completely sand the stone – does any impregnation or sealer for exterior use even make sense?