Browse Forums Building A New House Re: Brick/Mortar issues - pic heavy 3Nov 11, 2013 7:34 pm Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Brick/Mortar issues - pic heavy 10Nov 12, 2013 8:59 am Modified Fernside 38 Rawson Homes Blog: http://www.thehousethatmatandjenbuilt.blogspot.com Build Thread: https://forum.homeone.com.au/viewtopic.php?f=31&t=60501 Re: Brick/Mortar issues - pic heavy 14May 03, 2016 11:20 am I have a few comments regarding the above..... Iron oxide stain = Acid burn. Clay bricks don't cure as they are fired to become like stone, but concrete bricks require a curing time just like any concrete product. Clay bricks do swell over the years and this increasing size is taken up with expansion joints on homes where concrete bricks shrink. Acid burn is what its called because as you said, it is a reaction with hydrochloric acid [HCl] dissolving the iron content in the clay. You missed the No1 reason there is these problems. A large portion of iron stains are caused by a failure by the brick cleaner to pre-wet the bricks before applying HCl acid. If they pre-wet the bricks with water, the suction of the brick would be less likely to absorb the HCl acid, leaving the acid remaining proud on the wall and not soaking in to the brick. This means a brickcleaner will actually get better acid coverage as each litre of acid solution will cover a greater m2 of brickwork, thus saving the brickcleaner money. Applying acid to too much brickwork is also a problem as it gets to dry into the wall. On dark bricks or bricks in full sunlight this easily happens. Wetting the wall with a hose and watching how fast it drys can give brickcleaners an idea of what will happen when they apply a HCl solution. Watch a brickcleaner on site and you'll see that they very rarely test what happens. Also HCl is not neutralised by water as its either mostly washed away or diluted. If applied in a 20:1 mix [20 parts water to 1 part acid] and applied to a dry wall, a percentage of the solution will be absorbed into the wall. This will remain there as the high pressure wash cannot easily wash it out of the brick itself. It can then dissolve any iron in the clay and as the wall gets wet then dries pull the dissolved iron to the surface where it will remain as a stain after the water evaporates. A bicarbonate neutralising solution may render the surface layer "ph" neutral but it may not get deep enough into the brick to neutralise all the acid. Please note- Not all bricks are the same. Different colours can and normally do have different clay mixes and firing temperatures. Therefore some bricks need to be laid better and cleaner and washed in a different way with more care. Re faulty bricks.... NEWS FLASH Clay is mined out of the ground.... It can have traces of iron in it.... For a brick company to guarantee that clay has absolutely no iron AT ALL in it would be impossible! This is not avoiding liability regarding a problem with the brick it is a reality. Unfortunately the problem is this.... Brick companies need to make bricks at a price that builders will be prepared to pay for them..... using clay.....which may also have some amount of iron in it. For the past 20 years builders in Victoria have a shortage of bricklayers, especially in relation to the amount of houses they can sell and build. Basically...and unfortunately...over the past 20 years bricklayers in Victoria have developed a habit of laying bricks in a "dirty" state. They leave mortar residue ranging from blogs [or dags] to smears all over the bricks after they finish which need to be cleaned of the brickwork by a brickcleaner. There is no choice in this unless the builders were to pay bricklayers at least twice what they get now to lay clean....and in my experience many soon revert to laying filthy bricks because pride in their work is not what it used to be. This extra cost will be added directly to the cost of building a house and home owner simply don't want to pay for that cost. Please note- There are some very good clean bricklayers in Victoria.....but....there is not enough of them. That being said, bricklayers in QLD and Northern NSW do lay brick clean....simply because they have to. QLD is a mining state and it has a LOT of iron in the ground, therefore the brick clay has iron in it. If you don't lay QLD bricks clean, you almost certainly will get acid burn [iron stains] if you brick clean them and it will look terrible. In Victoria there is an apprenticeships in bricklaying....but only a percentage of bricklayers have actually done an apprenticeship. Most learn on the job after being a labourer for a bricklayer and its the same thing for brickcleaning. Bricklayers get paid approximately 20x the price a brickcleaner gets per 1000 bricks. So it all comes down to the following.... Builders concentrate on trying to keep costs down so homes cost less to build....so owners pay less to buy homes Victorian bricklayers are basically not as clean as QLD bricklayers because they don't have to be. Brickcleaners are needed to get a result that cannot be achieved any other way. Many brickcleaners don't pre-wet the brickwork [which costs nothing] and rarely do they also neutralise afterwards.[They are not paid to or they don't want to] Many apply acid over to many m2 brickwork and it drys into the bricks before they can wash it off. My 2c Being a builder is more than just having once held a hammer. It's about the trades you hire and ensuring that they give a result that meets the industry standard and the home owners expectations. 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