We have all seen that black lining behind caulking in the bathroom. No matter how hard you scrub, that stubborn blackness never goes. People have resorted to strip and reapply caulking but this problem still persists. This can be solved easily with some liquid bleach and baking soda. Before we proceed, some fair warning.
WARNING: Bleach fumes are harmful and will irritate eyes, nose and skin. Be careful when using bleach. Keep pets and children away. Use bathroom ventilation fans when using bleach. Use Common sense.
Step 1: Bill of Material
For this activity, we need following
1) Liquid bleach
2) Baking soda
4) Cheap paint brushes
Step 2: Preparing the Mixture
In this concoction, bleaching liquid is the main reactive agent, baking soda is just to hold bleach in place. Make a slurry of liquid bleach and baking soda in a disposable container. Container should have wide enough opening to easily use paint brush with. Mix enough bleach and baking soda so that it makes a runny consistency paste similar to pancake batter.
Step 3: Apply and Wait
Let bathroom dry out completely. Best time to apply this concoction is in the afternoon or when bathroom is least used. Apply the paste to all the caulking and areas where black muck is visible in bathroom. Let it dry for around 3 to 4 hours. Do not forget to turn on bathroom ventilation fans during application and drying period. For master bedroom ensuite, it helps to close bathroom doors and open one bedroom window. Baking soda helps to keep bleach in place and not run down. After around 3 hours, check once. If you see some areas are still black, pour some bleach over the applied mixture so it gets soaked again. Wait another hour.
Step 4: Rinse and Admire
After 3 to 4 hours, put on gloves and wash the paste off the walls and wherever its applied. Hopefully all the black muck will be gone and you will see gleaming white caulking. Enjoy your clean bathroom!