I had cardboard under a litter box on a wood floor and one of my cats peed on the cardboard, which soaked through to the wood and kept the floor wet. When I removed the cardboard the floor was still damp and had a dark stain. In this video I show the process of using hydrogen peroxide to lighten up the floor and remove the stain.
![](https://s2.save4k.ru/pic/HztkRmp9-TA/mqdefault.jpg)