Clean Black Mould from Silicone – Three Methods

Once silicone goes black it is very difficult to clean but there is a very easy method and if you are lucky it may work for you.

I always seem to be trying to stop silicone from going black. You know the silicone seal that goes around the bathtub or your shower. It looks lovely for a while and then goes black over time and looks really unsightly. Well here is how to fix that problem.

Why does SIlicone go Black?

Silicone goes black when it is damp and there are soap deposits on the silicone. This encourages mould growth and it’s the mould that causes the silicone to go black.

The good news is this is preventable. I have fitted silicone in some houses that only last a few months before going black and I have fitted silicone seals in other houses where it has stayed looking brand new for years. 

The difference between these two examples is that one household has many teenagers using the shower once or twice a day. The shower was getting used about 6 times a day, it was never cleaned down or dried after use and the silicone became black very quickly. 

In the other household the shower was used once or twice a day, was dried and cleaned after use – that silicone lasted about 6 years before renewal. 

I use the same make and type of silicone in every job.

Now both these scenarios are quite different and there could be differences between both bathrooms with regard to airflow but in general, if you dry off the seal after every use it will last for many years. The less you clean it the quicker it will stain and the harder it will be to get those stains off.

I guess what I am saying if you want silicone to last you have to dry it after use. That’s the best way to keep the silicone from going black in the first place. But, you’re here to find out how to fix it once the silicone has gone black. 

Let’s proceed.

Three Methods to Clean Silicone Rubber

There are three methods that I use for cleaning black, mouldy silicone. Each method gets progressively more difficult so it’s a good idea to start at method 1 and progress from there.

Methods 1 and 2 are both chemical solutions and method 3 is a mechanical solution. 

Before even starting any of these fixes the seal should be inspected for any damage. Make sure there are no splits, make sure the silicone has not come away from one of the surfaces. If the seal appears to be intact then the first two methods are good to try. If the silicone is coming off the wall or the bath/shower then Method 3 is your only option.

Method 1

Use a product called HG Mould Remover. (check the cost here – https://amzn.to/2r9whII)

This is a great spray to use as long as the silicone seal is in good condition – that is if it has not been compromised and the seal still works.

I have used this on some really black stained silicone and the results can be surprising. the less time the silicone has been black the better the chance of removal with the mould killer. 

All you have to do is spray this product directly onto the black silicone, leave for about half an hour and rinse off. The results can be amazing. 

The advantage of this method is it’s fast and easy to do. 

The only disadvantage is that it’s not quite as powerful as the other 2 silicone repair methods. It does smell very much of bleach so be prepared. 

This spray works really well with grout. If you have mouldy grout give this spray a try. No home should be without it.

If it helps I made a video about this mould spray, have a look below.

If this method is not working for you then you may want to try method 2

Have a look to see how to clean up black mould.



Method 2

This method involves the use of neat Bleach (undiluted bleach) – the thick stuff,  so you may want to have some rubber gloves and safety glasses. Be very careful when using bleach and don’t get it on anything you don’t want it on. 

For this method of getting silicone back to white, you will put bleach directly onto the silicone and leave it for 12 to 24 hours. To hold the bleach directly onto the silicone you will have to use some toilet roll and place this onto the silicone and add more bleach is required. You want that bleach soaked tissue on the silicone seal. 

It is important that you check that your fittings and wall will not be adversely affected by the bleach and is good to test in an unseen area first.

Once the toilet paper has bleach and is sitting directly on the seal then all you have to do is wait. Obviously, keep children and pets away for the time required.

I found that 24 hours works great but if it’s still not completely gone then just repeat the process. You should get rid of most of it if not all.

I have found the results of this method surprising and should get rid of almost all the staining. 

In the pictures, this part of silicone was black for years and after 24 hours most of the black was gone. Amazing! Usually, for that degree of discolouration, I would use method 3.



Method 3

Silicone removal. 

This is the most difficult method. Silicone is designed to seal two surfaces and in order to do that has to adhere incredibly well to both of the surfaces. If the silicone is not stuck then it’s not sealing. 

There are several ways to remove silicone but I have found that the chemical silicone removal products are not very good. My prefered method is to cut it out using a knife. This can be very tricky as you do not want to damage your tiles or scratch your bath. If you are not confident with a blade, a silicone removal tool like the one below would be good.

You can use a Stanley knife to get the bulk of the seal off. Then you can use a blade holder to get the rest off the tiles and just work away until you get it all off the wall and the bath. That may sound easy but it is not. It takes time and patience so give yourself at least two hours to complete this method.

Once all the silicone has been removed clean the wall and the bath with some white spirit and let it dry. 

Only when the wall and the bath are completely dry put on the new silicone. To put it on cut the nozzle at about a 45-degree angle and apply a bead of silicone at a consistent speed so you get an equal thickness. Then run over the silicone with either a wet finger (i recommend you wear rubber gloves) or a silicone finishing tool if you have one – a bit more difficult to use but will give you a better, neater seal. I use the finishing tools below which are excellent. There are cheaper ones available. Click on the pictures below and have a look.

The crucial thing about silicone is to be very tidy, keep it clean. Wipe up any silicone you don’t want to be there, if it doesn’t look good it won’t look better when dry and you will be stuck with removing the silicone again. A little bit of care goes a long way. When doing a bath I like to do one edge at a time, usually working from left to right – short edge, long edge, short edge. make sure the edge you have just done looks good before you move on to the next edge. 

Easy!


Stop Silicone Turning Black

Silicone is one of the main sealants used for sealing sanitary fittings for good reason. It seals extremely well, it’s very strong and it remains flexible for many years. It is perfect for sealing. 

The only problem is it discolours, it gets attacked by mould. There are silicones that resist mould and these are the types to use in your bathroom and kitchen. The mould resistance does not work permanently so – is there a way to prevent the silicone from turning black in the first place?

Yes, there is. Just follow these simple steps and you will save yourself a lot of work. 

  • Wipe off any soap scum or residue from the silicone around the bath.
  • Dry the shower area – if you dry up any wet silicone this will prevent anything growing on the silicone. Warm and damp are best for growing mould so bathrooms and kitchens are great for this. Just keeping the area dry will significantly slow down the growth.
  • Occasionally spray with a bleach cleaner if you see it is beginning to discolour or go black.

If your bathroom has a window or a fan make sure you use them to provide good ventilation. A lack of ventilation can be a cause of black silicone. I have vents on the bathroom window and make sure I have them open. If you have a fan make sure it is on, this will help a lot with keeping the bathroom dry.

If you follow these simple steps your silicone will last for years. I have been back to jobs the people who look after the silicone still have white silicone. The people who don’t keep the silicone soap-free and dry have black mould on the silicone within months. I always use the same brand of silicon so the difference really is down to care

It can be a real shame to go back to a bathroom that we fitted and see its rapid deterioration just because the seal has not been kept dry.


Choice of silicone. 

There is a wide range of silicones available. Over the years I have used different types from £4 to £10 per tube and more. You may think that the more you pay the better the silicone will be at sealing but that is not necessarily the case. I have used various types and found that some of the cheap ones are rubbish and so are some of the expensive ones. I use a type of silicone that gives consistent results.

A few years back I started using silicone at £7 per tube (that was more than double the price of cheaper silicones at the time) and under a trusted brand it was absolute rubbish and had to go back over the jobs I used it on to replace with a tried and trusted silicone. The silicone was literally peeling off the surface so the good thing was it was easy to replace. 

I have used this No-Nonsense Sanitary Sealant (https://amzn.to/2w1ATpQ) for some time and it works, gives a good seal, is very strong, is mould resistant and will last for many years if looked after. Mine is now six years old and still white.