I have a large family room, all the tiles I wanted to grout away. We moved here 6 months ago and have 3 dogs. So the mortar was dirty, but as I said, new 6 months ago. Within 45 minutes I blew out the grout cleaning brush. The bristles are curved towards the tip. I tried not to rub too hard, letting the steam soak in. Do the same with the green round brush. I used this for an hour and it's gone too. It took me about 2.5 hours to lay 800 square meters of tiles. Another thing that was annoying (I think all vapers should be) is that because the water needs to be heated, you get about 30-45 seconds of steam, then you have to wait about 20-30 seconds for it to settle down the steam has built up. up again. So you can't clean up all the time. We bought all attachments, extra mops and a mint cleaner. If it hadn't been a gift I would have sent it back simply because it went through the brush so quickly. I immediately ordered 2 more.