Step 1
Combine water and baking soda in a container to form a paste. Only a small amount will be needed to spread over the stain, so 3 tbsp. of baking soda and a few drops of water will be enough. Measure the amount of water needed by watching how thick the mixture gets while stirring it. Mix this with a dowel or with your hands until it is thick and will spread easily.
Step 2
Spread the paste onto the stained area and allow it to sit for about 10 minutes. Wipe the paste off with a dry, soft cloth.
Step 3
Combine 1 tbsp. of TSP in a 2-gallon jug with 1 gallon of water. Use the other dowel to stir the mixture until well-combined.
Step 4
Spread the mix over the stained area and allow it to sit for no more than one minute. Wipe it off with a dry cloth, and rinse the area immediately. If left on for a long period, it can cause discoloration on the ceramic, fiberglass, or tiled bathtub.
