Great for built in tubs and showers. Incredible rust, lime and dirt bathroom cleaner.** 2 cups vinegar 1 TBSP Borax 1 tsp washing liquid (dawn) Use a funnel and put the borax into the spray bottle then add the vinegar. Add the washing liquid and shake. I would add some type of essential oil as this smell is over powering. I had to walk away quite a bit because of the smell and come back.