Finally I found the real solution to get rid of mould growing on the silicon sealant in my bathroom and prevent it from coming back again.

Few weeks ago, I noticed two small black spots on the silicon sealant between the floor and the shower glass in my bathroom. It’s mould!

Mould on the silicon sealant is really, really difficult to remove. The reason is because the surface of silicon sealant is non-porous. Well, almost non-porous. Since the mould is able to grow there, so yes, it has pores, but a very small kind of pores that can only be seen in a microscopic level.

I had tried using various cleaners I have in my home, hunting for cleaning products in the supermarket, scrubbing it off with different tools, reading through many tips online, all in hope to get those tiny moulds off of my bathroom silicon sealant, to no avail.

Then I started reading more about the nature of mould, what they like and what they hate. I learn that mould has roots that are sometimes invisible to the naked eyes. The roots are growing and the more time you allow them to stay, the stronger and deeper the roots will be, making it even more difficult to remove. The pink, brown, or black spot you see on the infected surface is just the outer part of the mould.

Most of the cleaning products dedicated to tackle mould problems are actually only removing the mould that you see on the surface. They don’t really kill the roots because: 1. It’s difficult, 2. If you manage to kill off the roots, you won’t need to buy the product anymore (bad news to the product company).

Bleach is the answer

I also learn that mould hates vinegar and bleach. If you leave vinegar or bleach long enough to be in contact with the mould, the mould will eventually die. If you want to kill the mould to the roots and make sure it won’t grow back again, from my personal experiments, bleach will do a better job than vinegar. But you have to be careful when doing it. Bleach can cause corrosion over time that will ruin your furnitures if left for too long.

This is where it gets tricky. I have to apply bleach on the mouldy surface long enough for the bleach to kill off the mould, but I have to also make sure I only target the mouldy part to avoid ruining nearby surfaces. At the same time, I have to make sure that the amount of bleach I use is sufficient because it tends to evaporate if you just spread it over.

So this is what I do:

I use kitchen towel and bleach.

First, I pour the bleach into a spray bottle. Then spray the bleach to the kitchen towel until it’s completely wet. I use towel instead spraying or smearing the bleach because that way I can control the surface that is in contact with bleach.

Then I roll the kitchen towel firmly. I do this so that the towel will remain wet for longer, making sure that the bleach won’t easily evaporate.

Once the kitchen towel is rolled, I spray some more bleach, just to be sure it’s really wet.

Then I press the towel directly on the silicon sealant, making sure the mouldy part is fully covered. I leave it there overnight.

The next morning I woke up, the mould has completely disappeared! It was few weeks ago and until today, it’s not growing back. I have successfully kill it to the roots! Yay.

In case you’re wondering, I use common household bleach. It’s only cost about $2 for a big bottle. It’s way cheaper than any of those mould remover solutions I had tried prior to finding out that I just need bleach all along.

If you’re sensitive to bleach, you can also use vinegar. However, you may not get a quick result overnight. If you use vinegar instead of bleach, the mould will only gradually disappear. You should repeat it again for few nights until the mould is eventually gone.

CAUTION: Please test in a small amount first and check back every few minutes before leaving it overnight. Don’t forget to wear rubber gloves to protect your hands during the process.