Have done 2 jobs this week, both the same problem. Both customers recently moved in. Then both times black marks appear over next few weeks or so. I cleaned the carpets and the marks are very soapy but clean off fine and generally the whole carpet is pretty soapy. Had to use plenty of anti foam stuff.
So have the marks been treated with maybe vanish or something then either this has attracted dirt or is it the actual chemical that has become a dark mark?
Thanks Chris