Wow....thanks for the positive, constructive response.
Not 100% sure you should be questioning my company without knowing the first thing about it.
Actually the cleaners took it upon themselves to clean the grout and I'm just keen to fix the situation.
As a director of a cleaning company and not a hard floor restoration specialist, I don't pretend to be an expert in all areas of cleaning. That's why I visit forums such as this looking for advice in some areas.
Nick
I have helped you and have given you advice on several occasions on various floors over the last 3 years and would hope that the advice offered previously has been correct and accurate!
The point of the the reply is to highlight that you don't know the staining is caused by bleach residue, do you? If it was, you simply need to clean the residue off by rinsing! Moreover, as an aside if anyone in my employment took it on themselves to clean a floor with any product not supplied by me or not specifically in my RAMS and Instructions they would be looking for another job period. Rant Over!!!
Now to the task, the floor looks like it may be either honed limestone or porcelain bearing this in mind I would conduct a test area as follows:
1. Pre wet one of the stained areas with clean water
2. Agitate with a Mono Rotary fitted with either a natural hair or blue pad
3. Sprinkle in a little of 400 Grit honing powder and agitate again
4. Extract with a wet vacuum
5. Rinse and extract again
If it removes the stain, just crack on and do the whole floor. If it doesn't e mail me a close up photo of one of the stones with a stain on so I have more chance of identifying it or if it is in a commercial installation ask to see the O&M Manual for the floor.
Kevin