Read about this in Johnny Chuoke's column, "The Happy Handyman", for cleaning tinted grout. It comes with its own little grout brush. Spray it on, let it sit for a few minutes, brush with the included brush. IT WORKS! I had some high traffic areas in my laundry room on which I had tried everything. This takes care of it with very little effort. It is clear, has no odor, is safe for the environment, is biodegradable. Would recommend it without hesitation or reservation.

• How accurate was the sizing? Exact
• Please tell us about the quality of the product. Excellent
• Was the product free of any manufacturer defects? N/A

After trying various products to get my light colored grout lines clean this finally did the job !

• How accurate was the sizing? accurate
• Please tell us about the quality of the product. good quality
• Was the product free of any manufacturer defects? yes