Red Brick Has Developed A White Coating

 
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Old 02-14-2006, 09:57 AM   #1
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Red Brick Has Developed A White Coating


About two months ago I did some brick inlays into a sidewalk for a customer.
Since then a white film has develped on the bricks. It looks like a calcium build up of some sort but can not be attributed to an irrigation problem as there is no system in place yet.
I can use a wire brush and remove it but it may cause the brick to be removed to the point of actualy seeing brush marks. Of course this is not acceptable.
I am thinking that when I grouted the brick (grouted, let set up, scraped off excess, struck with 1/2" tool till smooth and then wiped brick clean with masons sponge)that some of the calcium from the morter got into the brick and is just now starting to come to the surface with the rain.
Is there any way to get rid of this problem? I was thinking about trying some muratic acid and lightly scrubbing with a wire brush.
Any ideas would be greatly appreciated. Especially since the customer still wants me to do a patio in the back yard and the front steps too. I really dont want this to happen to the steps especially.
BTW Im not an experienced brick mason so if I have screwed the pooch on this one go ahead and let me have it guys. *(assumes the position)*
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Old 02-14-2006, 03:29 PM   #2
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Re: Red Brick Has Developed A White Coating


what has happened is called "efforesence" (it is the salts that are left behind when the water evaporates) anytime you lay bricks or even landscape pavers for that matter you need to go over them with muriatic acid 1-2 days afterwards to "release" the salts the white haze will go away. mix the acid a little weaker than recomended and wash off thouroughly after applying it. there are also some other things out there that will work as well but i have found this to be the least expensive and easiest to use and find. READ the label first. FOLLOW ALL safety precautions on the label, ie gloves, glasses, not breathing the fumes etc etc this stuff can be dangerous if not used properly . hope this helops ya some. hopefully some of the experience masons on here can answer in more detail. ive only done small brick columns, and paver patios pertaining to this.

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Old 02-14-2006, 04:00 PM   #3
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Re: Red Brick Has Developed A White Coating


This is a problem we get a LOT over here, and is, as I Plant says, the salts coming out of the bricks. Its particularly bad if the bricks got very wet before being laid something that can easily happen if you dont take care to cover materials when the weather is bad. It will dissapear eventually on its own but it can take a long time. The standard way to get it off is to use a brick cleaning acid but you may find that it reappears again as more salts leach out.
Like I say we get it a lot so its easier to explain it away to the HO.
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Old 02-28-2006, 12:45 AM   #4
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Re: Red Brick Has Developed A White Coating


Take some dry sand and spread it across the bricks generously. Let sit over brick for a few hours. Sweep with a HARD bristle push broom until there is no sand left. Spray with water liberally until totally clean. This will work sometimes. If this does not work try some CLR (found at any hardware store) this works pretty good most of the time. If that does not work...Then you can use the muriatic acid. Do not use this earlier then 4 days after laying the brick. The mortar needs time to setup. You MUST make the mixture weaker then the bottle says to. You will mess up your joints.

Also what type of bricks are they? What type of mortar?

I hope this helps you!


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Old 02-28-2006, 08:33 PM   #5
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Re: Red Brick Has Developed A White Coating


"Efflorescence" is the technical term and it is caused by various salts migrating through the face of the brick/CMU. There are a lot of causes, including the mortar, the masonry unit itself and water infiltration into the brick. It is especially prevalent on face brick used on flat work. It is easier to tell you what NOT to do than to tell you how to fix it, and this applies to both flat work and walls:

Never use anything but clean potable water for your mortar, and depending upon your geographical location NEVER use well water.

Never use anything but clean washed masonry sand for your mortar.

Never, ever pressure wash masonry.

Never, ever use muriatic acid on masonry, no matter what the concentration. I know it has been used by your grand-pappy with no problems for a hundred years, but that only makes it possible, not correct, and it will void most warranties on masonry units.

This is what you should do:

For flat work, consider using concrete pavers instead of hard fired clay brick, especially when inlaid into concrete (because of the difference in thermal expansion/contraction characteristics).

Use a proprietary cleaner designed for your particular type of masonry, as recommended by the manufacturer.

Almost all masonry can have a first blush of efflorescence after installation, so wait as long as possible to address the issue after the install and initial (mortar) cleaning. If the owner insists on immediate cleaning, do it very gently, and alert the owner to the possibility of a reappearance in the near future. If it is an issue in your area, figure a second cleaning into your bid.

For flat work, the sand method works well.

Realize that efflorescence is a forensic tool to determine other problems with a project, such as water infiltration, poor flashing details, and defective materials, but only if you can show that you did not cause the problem by your installation and cleaning methods.

Also be aware that each particular type of efflorescence has a different cause and a different solution.
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