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.
If you have clear silicone in your home (perhaps being used as a sealant or caulking for your tiles or tubs), then you may notice that over time it becomes yellow following exposure to light and humidity. The good news is that this yellowing is temporary and it can be removed with normal household cleaning products.
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.
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.
Hydrogen Peroxide. The mild bleaching ability of hydrogen peroxide makes it a practical tool when you need to remove mold from shower caulking and other bathroom surfaces. Add undiluted 3% hydrogen peroxide to a spray bottle and apply it to the stain. Use your soft-bristle brush or a sponge to clean the affected area.
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.
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.
Silicone and silicone-blend caulks are most commonly used for kitchen and bath caulk projects. They are the best kind of caulk for showers, bathtubs and sinks.
Like WD-40, vinegar won't magically dissolve silicone caulk. 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.
Ready for water exposure in just 30 minutes, this waterproof sealant is mold & mildew resistant. The clear silicone sealant won't yellow, shrink or crack over time!
Remove White Powdery Residue From Silicone
To remove the problem, soak the silicone pieces in distilled white vinegar for about 30 minutes. The vinegar will cut through the mineral deposits. Rinse the pieces well and dry with a microfiber cloth.
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.
Some are intentionally made to change hues, while others become discolored due to mold, dirt, extreme temperatures, and excess moisture.
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.
Why is bleach damaging to silicone sealant? The cleansing abilities of bleach are undeniable, but it is simply too much for delicate silicone rubber. As a porous material, the structure is easily weakened by harsh chemicals.
Bacteria Growth
Old caulking can contribute to the growth of bacteria as well as mold. Those who notice an orange or pink substance in their showers are probably looking at a bacteria called Serratia Marcescans. This mold is linked to illnesses like urinary tract infections, pneumonia and even meningitis.
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.
Soak the case for a few minutes in a bowl of warm water, 1 teaspoon of bleach and 1 squirt dish soap (bleach damages silicone, so only use a little bit). Gently scrub the case with a dampened magic eraser till all the dirt is removed.
There are various cleaning agents that can be used to effectively clean caulks. Ammonia and bleach are toxic cleaning agents that very effective. Vinegar, hydrogen peroxide and baking soda are non-toxic cleaning agents.
Vinegar – or a combination of baking soda and vinegar – is touted as a safe, 'all-natural' cleaning solution for silicone sealant.
Clear phone cases are normally made from silicone—a polymer that's popular for its inexpensive and flexible properties. Unfortunately, these polymers turn yellow as they age. This natural process is accelerated when they are exposed to excessive amounts of chemicals, light and heat.