Please can anyone tell me what this is and does it matter.
I have had a new wall built (in a conservatory) about 6 months ago. Recently a white powdery substance has appeared around the mortar in a couple of lines of the bricks. It seems to wash off but then comes back (so perhaps washing just makes it appear it has gone). Any ideas what it is please?
This is nothing to worry about - I've seen new houses with this white dust on them. It's something to do with the fact that they are new bricks coupled with damp weather - in time the white powder will disappear and you will forget about it.
Im pretty sure its salt leeching from the new bricks. Quite common and will disappear eventually. (Lick your finger and taste it. :)
Peter
Spot on. Called effloressensce, and can come from either the bricks or the mortar. Not much can be done to remove it, but wetting the bricks will cause the salts to come to the surface where they can be brushed off.
SalesGuy
OK thank you all very much
There's some stuff that you can get from Homebase etc - probably called "brick cleaner" - usually sold near where they sell concrete acclerator (its a liquid sold in containers). Its hydrochloric acid & will dissolve the leaching from mortar work. - Just be careful to folow the safety advice
This from Brick Development Association: Q. A typical question from a contractor is, 'We have recently completed an office block where the brickwork is covered in a thick white efflorescence.' Is there any way of removing it quickly before hand over? A. Unfortunately there is no quick and permanent way to remove efflorescence. It could have been prevented initially by adequately protecting the brickwork during construction to stop large amounts of water entering the uncompleted brickwork. Extensive white efflorescence is usually indicative of ineffective or no protection.
It is preferable to allow the efflorescence to weather away naturally. However it is possible to remove it by brushing with a soft bristle brush. The deposit should be collected and removed so that it does not have the chance to enter the masonry at lower levels if the brickwork becomes wet again. Any deposit remaining may be removed or reduced by sponging with clean cold water.
Chemical methods are not necessary for the removal of efflorescence and are best avoided. Some manufacturers have products that purport to remove efflorescence but the Brick Development Association believes they are unnecessary and that the procedures described above are effective and less costly.
Hmm, probably wise advice given the source, and I suppose that HCl is not that welcome in the environment. I just remember seeing it in the sheds....
Yeah it's good advice. Absolutely nothing to worry about. It will die down in time, (months) It's easily removed with a stiff brush and plain water. Don't bother nuking the environment with acids, it will only go away when the bricks have sufficiently dried out. If you are talking a low wall round a conservatory I'd hazard that by August you'll have forgotten all about it.
As an aside you often see it going on for ages on tall garden walls and the like, purely because they get wet repeatedly from all angles. Especially if they don't have a top course in engineering brick, or tiles.
Al
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