I had to clean my shower doors and walls about 4 times coz the soap sum had built over the years even after rinsing it after each shower first time was a mission, 2nd time was starting to look ok,3rd time my arm was getting sore with improvement 4th time finally it worked now I know use the koala cloth after each shower then it wont be as hard. The most important thing is that it worked thankyou koala π¨