(Get Serious) "Bubbles-up" stains & odors from under carpet padding to top of carpet where it can be absorbed in a thick towel - toss towel in the next wash load! No urine is left under padding to "wick-up" to top of the carpet during drying, so no "yellowing" can occur! The urine isn't neutralized, but actually lifted to the carpet top & removed. Pets don't re-mark - they cannot smell it, their "pheromone" is gone! For stubborn stains, warm bottle in microwave before applying. A great Feline "spray and vomit" cleaner too! Dog Fancy "Editor's Choice Winner 2004".