We have marshalls patio flags and we'd like to seal them because they have become dusty. I bought some stuff made by Thompsons, but the patch test I did came up with a sheen when the flags are supposed to be matt.
I rang Marshalls and they said they would advise me not to seal the flags. I don't know whether they are just being over-cautious.
Has anyone successfully sealed patio flags made from pressed concrete with a matt finish?