Brown marks on new grout!?

[uug197h]

Brown marks on new grout!?
I just finish to re grout one of my customers shower and they call me today some brown marks appears on the new grout, any reason for that .
I re grouted quite few showers and bathrooms and never had that kind of problem before . Shell I use different grout then the standard grout I used so far?

Thanks Sasi

Question from plumbing forum

thanks uug

[faithhealer]

Obvious question for him Uug is were his tools clean?

[kilty55]

thats what i was gonna say,,was his float clean?

[Alan.P]

As daft as it might sound, it's not adhesive / old grout that hasn't been cleaned off the tile before re-grouting.

[whitebeam]

Is it some wet dust from the biscuit of the tile, a mate had the same problem the other day he used bal grout

[Fred]

I used my fien grout remover tool once, I must have chipped the tile as I was called back to 'bleeding' in the grout, a sort of brown/pink colour.

[doug boardley]

once had some staining appear on grout, we think it was coming from the wbp! as we'd ruled everything else out