Review on Waterproof Brown Grout Pen Marker: Tile Grout Colorant and Sealer with 5mm Narrow Tip (7mL) by Mike Burnett

RATING 1: I've been trying to clean grout in the kitchen, dining room and two bathrooms for a year with no success. It should be light brown, but it contains an unknown substance that simply cannot be cleaned. Regardless of what I used, the solution looks the same within a few hours. I bought three of these handles to experiment in the bathroom first. I've just spent over an hour cleaning a bathroom and am very disappointed that it took all three handles! They are easy to use but not very durable. I didn't use them roughly, but the tip of the first pen started falling apart after a few minutes. It was a very frustrating process as the pens are really short lived. I'm not thrilled with the results but I think it's better than what I started with. I really want to see if the color stays. I would like a refund but instead I have to order more because I don't know what else to try and of course I can't find it anywhere else. UPDATE: I bought four more pens and used all four again in SMALL 2nd bathroom! The handles are not durable at all. They're like a bag of potato chips - only half full. I was afraid I would leak before I was done. I think the grout looks better than it was but I'm not happy that the handles don't last much longer for the price I paid.