Mould on internal walls and ceilings is unsightly, unpleasant and in some situations detrimental to the health of the occupants, so it’s important that the problem is dealt with properly when it arises. Too often I’m asked in my role as a professional decorator, “Can’t you just paint over mould with something?”.  Well, I could do, but it wouldn’t work, and the mould would return, so in my eyes I wouldn’t be doing my job properly.

The important thing to remember is that mould is a living organism; painting over a herd of cows won’t stop there being cows in the field, and it’s the same with mould on your bathroom ceiling, (or wherever else in your property it appears).  Mould is actually a type of fungus, and fungi like warm, damp conditions.  You don’t see mushrooms growing in the middle of winter, because it’s too cold, and you don’t see them in the heart of the summer, because it’s too hot and dry for them.

Mushrooms are most visible in autumn, when the conditions are right for them to grow – warm and damp. And mould is exactly the same. So, the best way to get rid of mould on your ceiling is to kill as much of it as possible, and then change the conditions so that the mould is not encouraged to return.

I like to think of it in terms of four key steps to solving the problem:

1. Change the environment to make it less attractive to mould
2. Kill as much of the mould as you can
3. Treat the area to prevent the stains left behind by the mould from bleeding through your nice new paint
4. Paint with a product that contains mould-inhibiting ingredients to further discourage mould from returning.

1 – Change the Environment

As mentioned above, mould thrives in warm, damp conditions.  Bathrooms and kitchens are often perfect places for mould to grow. Warm moisture in the air – from showers, or from cooking – comes into contact with a cooler surface (walls or ceilings) and condenses, leaving tiny water droplets on the surface which the mould needs to survive. Having an extractor fan installed which is powerful enough for the room in question will suck that warm moisture out of the room, removing what the mould needs to survive.

Missing out this step of the process leaves an environment which is still ideal for mould to grow in, so even if you follow the other three steps, the mould might still return to your ceiling.  Occasionally mould does appear in other places around the home, such as behind large items of furniture positioned close to walls.  Moving the furniture allows this space to “air”; the mould appears in these situations because there isn’t enough air movement around the room, so “stale” warm air gets trapped in these spaces and mould can form.

2 – Kill the Mould

These days there are some excellent mould-killing products available at affordable prices online, at decorators’ merchants, and at DIY stores, so we no longer have to resort to soaking the area with bleach. My favourite product for killing mould is Zinsser Mould Killer & Remover, which is available online here. It is really easy to use but does contain harsh chemicals so I would recommend wearing suitable protective clothing (gloves, eye protectors) when using them.

But it really is as simple as spraying the affected area, waiting a few minutes for the product to kill the mould, and then wiping the area clean with a damp cloth. In really badly affected areas, you may need to repeat the process a couple of times, but afterwards the mould will have gone, and you may be left with just a few stains which won’t wipe off.  Don’t worry about the slight staining – that’s normal and we deal with it in the next step of the process!

3 – Block the Stain

This step is really simple too, but essential – those stains left by the mould will simply bleed through ordinary emulsion paint, so your newly-painted ceiling won’t be looking pristine for very long. But help is at hand. Zinsser make stain blocks in handy aerosol cans that you can simply spray over the affected area and leave to dry. Or, if you’re worried about overspray onto adjacent walls, tiles or whatever, use the old-fashioned method (still my preferred way!) and simply give the area a coat of Zinsser BIN primer (or HB42 “Primer Sealer Stain Block”, or Fiddes “Full Stop”, which are similar products).

Zinsser BIN is a magic little product which every professional decorator carries somewhere in his or her van, and it has a multitude of uses – one thing it’s particularly good at is blocking stains. So, a quick coat of BIN on your treated mould, wait for it to dry (make a cuppa!), and then you’re ready to paint over with your emulsion.  BIN dries to a creamy “off-white” (see photo), so you will always need to paint over it. Click here to see online prices.

Three Top Tips When Using Zinsser BIN to Cover Mould:

1. When you buy a tin of BIN, buy a bottle of Zinsser BIN Brush Cleaner at the same time – it’s the best thing for cleaning out your brush afterwards (white spirit won’t work with BIN)
2. Stir the product really thoroughly every time you open the tin. Giving it a quick shake isn’t enough – the solids in the paint tend to sink to the bottom of the tin and form a sticky mass – you need to stir thoroughly to make sure these are properly mixed in the paint to get the best result over mould.
3. Don’t be surprised if, when you emulsion your ceiling (or wall or whatever), the areas that you treated with BIN take longer to dry. Paint dries by both evaporation and absorption, and BIN forms a barrier which stops the stain bleeding through, but also reduces the ability of the plaster to absorb moisture from the paint. Just wait until your first coat of emulsion is thoroughly dry all over before applying a second.

4 – Choose a Suitable Mould-Inhibiting Paint

Again, there are some fantastic products around these days which not only look great on your walls and ceilings, they help solve the mould problem at the same time. Personally, I find the best product for painting walls and ceilings in bathrooms is acrylic eggshell; these paints are slightly shinier than matt, but are really easy to wipe down and don’t show the condensation “run marks” which are often a problem in bathrooms (especially if you have teenagers in the house!). The two which are widely regarded as the best are Zinsser Perma-White (somewhat confusing, as their eggshell finish is called “satin”, and if you buy from a specialist, Perma-White can actually be tinted to other colours apart from white. If you buy from the Decorating Centre Online, they will match any colour from any other brand. Click here to see online prices.

Crown Trade Clean Extreme Mould Inhibiting Acrylic Eggshell (which is available online in white and a whole host of colours) is another great product.

Both of these contain mould-inhibiting ingredients to try to reduce the chances of mould appearing on your paintwork in the future.  Both are also available in a matt finish if required. Personally, I love the Crown product (pictured) – I’ve just finished a small bathroom using it, white on the ceiling and a colour on the non-tiled walls, and it’s a lovely product to use and gives a nice finish. Click here to see online prices.

So, there you go, four simple steps to help eradicate mould in your home – improve the environment, kill the mould, block the stains and then paint over with a suitable product to keep the mould at bay!

How Get Rid of Mould on a Ceiling  – by Robin Gofton