wrote:

Hi, I'm building a retaining wall in my garden and I've seen these
bricks on ebay
http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=5966785622

I was wondering if anyone here had any comment about the white marks on
the bricks. Is this effloresence? Do all bricks do this or is this a
sign that these are not of low salt content thus I would need to use
sulphate resisting cement? Does the white go away once washed off?


Just leace it for a year. It washes off.

Its a sign thet the bricks are wet and porous: Salts leach out of the
cement and migrate by osmosis to the surface of the brickwork

Eventually the rain will wash them off, or of an instant result is
needed use brick acid.

My other easiest option is just going to my local wickes but I'm not
really sure of the rating of their bricks either other than they say
they come with a "frost guarantee".


Frost guarantee generally means they are of sufficielntly low porosity
not to retain mositure in the surface layer, where it can freeze and
lead to surface flaking.

Thse will be better at efflorecsence, but probably still shhow it.
Frankly, with todays climate, I would not worry.

I had my new chimneys covered in it. Two years latyer no sign is left.

Am I worrying too much?