Is mould inevitable on silicone in a shower?

Firstly, choose a good sealant incorporating mould inhibitor.

The only way to avoid mould growth, it to ensure that the sealant does not stay wet. Wiping down after use, coupled with adequate ventilation of the area, are both essential.

There are also mould inhibitor sprays which are pretty good as an additional preventative measure.

To recap, if you repeatedly allow moisture to remain in contact with the sealant for significant time, then mould is practically inevitable.

Chris

If it stays wet, then mould is inevitable, IME even in the stuff allegedly containing inhibitor.

I had a shower which was extremely prone to mould, but changed the bathroom extractor fan to a humidistat-controlled one. Result - nice dry bathroom and no mould regrowth.

David

David and Chris are right. Keep it dry by wiping down after showering. A micropore cloth is very good for that.

Mary

Agreed but can I just add ' gently ' because it can also be pulled out.

Andy

It's more like mould in silicone sealer is inevitable. The sealer contains acetate, a by product of the curing process, which is very tasty to mould, in laboratories moulds are often cultured in an acetate solution.

One solution is to use a more expensive sealant. However these are also not without their problems. I use "Evostick Nail and Seal" for many jobs. It's far superior to silicone since it is a sealant designed for use below the waterline in boats immersed in salt water. It does not support the growth of mould. Sadly if used where it can be seen, it has the unfortunate characteristic of yellowing with age.

An alternative is to use a polyurethane sealant such as Sikaflex which is also resistant to moulds.

Thank you all for the information. Keeping the silicone sealant dry seems to be important. I am not sure why the silicone sealant used in window frames never seems to get mouldy: it is often very wet for long periods in rainy weather.

Steve, your suggestion to use materials other than silicone sealant is interesting. If the choice was between a yellowing seal or a mouldy seal, I should be happy with the yellowing one. What do the phrases "does not support the growth of mould" and "resistant to moulds" mean? Do they mean you will never see mould on such surfaces?

Regards Sal.

If that's so why do people have such a problem when they try to remove it?

Mary

Because I'm not suggesting it rips it out completely but damages it.

My wife is a particular stickler for looking after the bathroom and after many years, there really is hardly any noticeable deterioration, all down to her, oh and of course the care with which is was first installed ! ;-)

Andy

You mean you expect her to clear up after you.

No but I WAS expecting that !!! I admit that it would not be quite so pristine if I was solely in charge. On the other hand she would be living in a hovel or a lot poorer !

Andy

It's my pleasure.

I doubt it.

Mary

Has anyone tried this stuff?

1. Use expensive sealant with fungicide (eg Corning 785).
2. Install decent fan to ensure proper ventilation of shower area. I fitted a £30 humidistat controlled fan, waste of time as it had no temperature compensation so in winter would either come on by itself when cold or be triggered by the shower and never turn off. A £120 Ventaxia (?) humidity controlled temperature compensated fan cured that.
3. Use a water softener. Since fitting a water softener not seen any mould growth in both my showers, despite poor ventilation in one, which did suffer mould issues.

In my experience these year markings are like wristwatch water depth markings (25m = splashproof, 50m swim, 100m dive underwater).

I find dividing them by 5 works OK:

Guaranteed 10 years ; you might get 2 years without mould. etc.

I use the "guaranteed 35year" ones from the sheds, in the hope they might last 7.

I'm guessing that you are joking? There's not much chance of my house being standing in 35 years, never mind the shower that the sealant is attached to! Anyway, I shall be past caring about mould by then.

"Does not support the growth of mould" means there's no acetate in the sealant, acetate is the growth medium for mould.

"resistant to moulds" means that unlike silicone, mould doesn't grow in the body of the sealant. If you look at mouldy silicone you will find it impossible to clean off the mould because it penetrates into the sealant. Hence rubbing at the surface will not clean it. With the Evostick co-polymer sealant and tiwh Sikaflex mould may form on the surface in damp conditions but it can be wiped off with a cloth.