Removing mould

[vicky whitworth]

Such a motivating topic for a Saturday morning. It's damp and wet down here in Devon and I want to spruce up the cement render on an exterior wall which is currently painted in white Sandtex. My plan is to use a more cheery colour but to stick with the Sandtex. My question is what should I use to remove the patches of green mould prior to re-painting? Could I get away with scrubbing them off with a bit of bleachy water or should I use some 'product'? I seem to recall advice being given to Jose on this a while back about her terrace wall in London but I can't seem to find it.
Thanks.

 

[Penners]

I'd certainly use a solution of bleach. Be sure to scrub it well into the texture of the cement, leave it to work for a while then rinse off. Obviously let the wall dry before you paint.

You can buy all kinds of proprietary mould-removal products, but I reckon bleach works just as well, at a much lower cost.

I don't know whether you have any plants growing against or near the base of the wall, but if you have bear in mind that bleach won't do them any good at all.

 

[Feltwell]

The paint manufacturers will recommend you use a fungicide:-

http://www.sandtex.ie/planning/preparation.html

Which can be bought from the likes of:-

http://www.tradepaintdirect.co.uk/index.php/sandtex-trade-fungicide.html

or

http://www.diy.com/diy/jsp/bq/nav.j...mpid=4&tmad=c&ecamp=cse_go&CAWELAID=266888184

Shame you're not closer, I have a bottle in the cellar you could have!

I don't see why bleach wouldn't work though, as Penners advises, so long as it's washed off thoroughly.

 

[Schoolmarm]

Algon is fantastic. It takes a few weeks to turn black but then is easily washed off and better still none of it then goes on to grow somewhere else.

 

[Penners]

Shame you're not closer, I have a bottle in the cellar you could have!

If it looks anything like this one, I'll be over - distance no object.

 

[Feltwell]

Alas Penners, whilst Sandtex Fungicide may have a bit more kick than Dom Perignon, it's nose leaves something to be desired, never mind the aftertaste. I also suspect only this man would survive drinking it. From this picture, it appears he may have just finished a glass or two.



Am I alone in finding champagne deeply overrated? Give me a glass of red wine any day - or preferably a nice pale bitter or glass of Auchentoshan or Glenlivet 18

 

[Penners]

Am I alone in finding champagne deeply overrated?

Overpriced, yes. Overrated - absolutely not! Luvverly stuff!

 

[LadyArowana]

Am I alone in finding champagne deeply overrated? Give me a glass of red wine any day - or preferably a nice pale bitter or glass of Auchentoshan or Glenlivet 18

If it comes to a vote then I'm in the champagne camp!

 

[Feltwell]

I haven't fainted with shock at that one, Lady A :wink:

 

[vicky whitworth]

I think I've got the hang of it. I can either spray champagne up the wall or slop on a coat of red plonk - either will get the mould off - it's just a matter of personal taste? And I just drink the bleach.

Thanks for the advice on the mould, guys. I'm going with the cheap and cheerful bleach option.

 

[Keithj]

I'm wondering how bleach would react with lime render.

My chemistry O-Level is a very long way away so I can't be sure, but I suspect it may be interesting.

 

[Feltwell]

Wouldn't have thought it would do much - bleach and lime render are both heavily alkaline.

Happy to be corrected by anyone with more memory of O level chemistry than me though!

 

[Penners]

Bleach is strongly alkaline - pH 12. Lime plaster also has a pH of 12 when wet, but that drops to 7 (ie: neutral) once it's carbonated.

The easy way to satisfy yourself is to try a test patch - I reckon it'll be OK.

 

[AMc]

As above bleach on lime shouldn't have any effect as they're both alkaline BUT the other common tip for dealing with stains is white vinegar which is acidic and would react. Brick acid a.k.a. patio cleaner would seem to be a bad idea
I suspect that in any case the amount of acidic cleaner you would need to clean off mould wouldn't have a serious impact on a lime render but would probably mess up limewash.

On the champagne thing - I find that a glass is nice but half a bottle (birthdays and anniversaries) often leads to acid indigestion which spoils the point. I won't drink any other white wine for the same reason. I'm always tempted to spend £20-30 on a bottle of red in preference as I believe champers is over priced. As I know almost nothing about wine I'm unlikely to make an informed choice about an expensive red so the 'traditionalist' in me usually ends up with a bottle of Verve Clicquot .

 

[Penners]

On the champagne thing - I find that a glass is nice but half a bottle (birthdays and anniversaries) often leads to acid indigestion

Then you shouldn't be drinking half a bottle of champagne. A full bottle will solve your problem.

You'll still get indigestion, but you won't care.

Verve Clicquot

The widow Clicquot undoubtedly had plenty of verve. :wink: