that chemical didn't helped. Left for 45 minutes, cleaned, rinsed... but nothing happened... :/
So let me get this right!
1. You pre wet all the grout and tile with clean water
2. You sprayed the solution on and let it dwell
3. You agitated it with a brush
4. You rinsed it and dried it
And you are saying there was
no difference!
Is that correct?
Because if so, you are the first person I have ever come across that it didn't work for! I sprayed it on a Belfast sink in a school that had black and green mould on it that was at least 2- 3 mm thick and it totally removed it using the above process. I also tried it in a bathroom with zero ventilation that had mould a lot worse than in your photos and it left it immaculate.
Please post the after photo!
Where is the job?