If your sealant or silicone has gone yellow or is in the process of going yellow, don't worry. It is a common occurrence. Your sealant is likely going yellow because of exposure to UV radiation.
All neutral cure silicones will yellow due to oxidation of one of the raw materials. The problem can be exacerbated if the silicone is in a dark closed room, away from daylight (UV). It can be reversed by exposing the silicone to daylight, but over time it will eventually yellow.
Chlorine bleach is a common product used to whiten caulking and grout. However, chlorine bleach contains harsh chemicals that can discolor a variety of surfaces. Instead, use oxygen bleach--which has all the benefits of chlorine, without the risks--to clean and whiten silicone bathroom caulk.
Silicones may yellow in the absence of sunlight or due to reaction with certain substrates (e.g. bitumen) or substances (e.g. cigarette smoke). Acid-based silicones and colored variants are more resistant to this. However, yellowing does not affect the adhesive strength or properties of the sealant.
If you notice the caulk around the base of your toilet start to turn brown, it means your toilet has a wax ring which is leaking. As a result, human waste especially urine is decolorizing the normally white caulk. The solution to this is to remove the toilet and put a new wax ring.
Try some standard bathtub cleaners on it. Also use a solution of bleach. This will kill the mildew and may bleach it somewhat. If you still are not satisfied with its appearance, your only other option is to replace it with new caulk.
The good news is that this yellowing is temporary and it can be removed with normal household cleaning products. Simply spraying some household bleach onto the silicone and allowing it to sit for 10-15 minutes before rinsing it off will get rid of the yellow colour.
Use baking soda
It is fantastic at removing stains and the yellow color. You need to sprinkle a small amount of baking soda on the case. Using a wet toothbrush, scrub the exterior and interior gently. Once done, rinse the case and dry it with a soft cloth.
Transparent silicone products will turn yellow over time, This is not a product quality problem, this is the characteristics of silicone. The reason for this is that the silicone rubber needs to be added to the vulcanizer when it is molded, and the vulcanizing agent will turn yellow over time.
A mixture or water and hydrogen peroxide and water, or a mixture of hydrogen peroxide and bleach, will kill both bacteria and mold growth on caulk. For lighter surface cleaning, a mixture of vinegar and water can be used, too. For best results, alternate the type of cleaning mixture you use.
Unlike most other bathroom sealants, BT1 will NEVER turn yellow over time. This is because of its unique TRIBRID® Technology that has given this unique sealant the ability to resist and prevent bacteria and mould from growing on its surface.
Gorilla 100% Silicone Sealant is great for kitchen, bath, window, doors, plumbing, gutters and more! Ready for water exposure in just 30 minutes, this sealant is mold and mildew resistant and won't yellow, shrink or crack over time!
It is recommended to replace the caulk in your bathroom every 5 years, even if it isn't showing signs of wear and tear. By maintaining and replacing your caulking regularly, you prevent damage that may be caused by peeling, cracking, mold or mildew.
Hydrogen Peroxide
Use the cleaning agent diluted or undiluted, and place directly on caulking where mold is most present. You may need to apply multiple layers, but this cleaning agent should kill off present mold colonies, and whiten their stains too.
Vacuum or sweep up any dust or debris that has accumulated in or around the caulk. Create a bleach solution (1 part bleach to 10 parts water) and pour it into a spray bottle. Spray your shower caulk with the bleach solution, paying special attention to the affected areas. Let stand for at least five minutes.
UV Light Exposure
It's what causes sunburns, and it can also damage plastic items like phone cases. When plastic is exposed to UV light, it breaks down and becomes yellowed or discolored. This is because UV light causes the molecules in the plastic to break apart.
"A ratio of 1 tablespoon of bleach to 1 cup of water should be ideal. Wearing gloves, wipe this mixture over your yellowed plastic. Leave for a few moments, then wipe away with water." Don't forget to put on some rubber gloves before handling and wash your hands thoroughly after dealing with any chemicals.
Hydrogen peroxide can also be used to clean silicone but only if you use it diluted properly. First, mix equal parts of concentrated hydrogen peroxide and distilled water in a bowl. Then dip the silicone into the mixture for 3-5 minutes and wash it with fresh water afterward.
EVO-STIK Stay White/Clear Sanitary Silicone Sealant is a high quality, moisture curing sealant that won't stain, blacken or yellow – leaving bathrooms and kitchens looking fresh and clean for life.
Under the action of the catalyst of many white silicone rubber products or transparent products, the product yellowing and discoloration will occur due to the high processing temperature or the high ambient temperature and the influence of heat.
While bleach is usually the go-to remedy for banishing stubborn bacteria, cleaning experts have warned against it to avoid damaging the silionce around your home.
If you still have moldy caulk, put some bleach in a spray bottle and wet the walls down right above the plastic wrap. The bleach will run down underneath the plastic and re-saturate the paste. You can do this as many times as it takes, but even with my super-nasty caulk, I only needed to re-apply the bleach one time.
However, vinegar will loosen up particularly stubborn caulk if you don't have a commercial caulk remover in your supply closet. Vinegar can also be used to clean and disinfect gaps after you've pulled out all of the old silicone caulk residue.