Replies

1. 
   Wilson504 | Apr 21, 2002 06:32pm | #1

   What you are seeing is referred to as "efflorescence. It is the calcium carbide leaching out of the mortar in the brickwork. You may also see it in a concrete basement as well. Basically its harmless but it is usually an indication of water being present, as in a wet basement..or a lack of a proper vapour barrier in areas above ground.

   Its likely to re-occur if you can't remedy the moistue problem. Wash it away with a mild acid if it bothers you enough..Carefull with the acid though..not only personally but on your brickwork too..Its likely to clean your bricks more than you'd like..You may end up doing the entire house.

   Goodluck

2. 
   bobhallsr | Apr 22, 2002 01:56am | #2

   With older, softer bricks the presence of efflourescence can be accompanied by deterioration of the brick. In that case it is necessary to fix the moisture problem. I'd guess that your 1920s brick is hard brick. BTW, it's probably not calcium carbide. That's what is used in cavers headlamps to produce acetylene.

   BJ

   Gardening, cooking and woodworking in Southern Maryland
1. 
   ClevelandEd | Apr 22, 2002 02:21am | #3

   Hard brick?  That makes me wonder if I have soft brick in my house.  It was built around 1840.  There was a lot of extra brick in the basement surfacing the floor.  I pulled it up and used it for the exposed foundation portion of some work I had done.  After half a dozen winters here I can see deterioration.  It is as if the brick absorbs a lot of moisture, then maybe flakes off when it freezes?   I should have known that those bricks could be a problem when I was pulling them out of the basement and was amazed at their "crude" quality.   I wonder if i should try sealing these, or just leave well enough alone.  The deterioration is with specific bricks, and is not universal.  I have pleny of bricks in the basement to replace any that have to be pulled out of the foundation. 

1. 
   ClevelandEd | Apr 22, 2002 02:27am | #4

   Sorry Scrapsy, I added my own question into a discussion that you had started.  I have had that white powder appear in my basement, and my experience is with the advice that says to fix the moisture problem.  Eliminate the water, and you will eliminate the visible traces that result. 

1. 
   jc21 | Apr 22, 2002 04:25am | #5

   If it's from the 1840's it's more than likely a soft brick. http://www.bia.org/html/frmset_thnt.htm

   They usually require a lime mortar. Modern mortars are too unyielding and agravate spalling problems. Your 1840 bricks are fine for interior use but probrably not the best choice for exterior use.

1. 
   ClevelandEd | Apr 22, 2002 04:43am | #6

   Lime mortar?  I can pretty well assume that the Amish work crew didn't switch to lime mortar when they switched from concrete blocks to the visible 1840's brick.   Well, now I know that my spalling problems may be aggravated.  Interesting what I learned about my own residence when I went to read a posting that appeared to have no relevancy for me! 

2. 
   jc21 | Apr 22, 2002 05:10am | #7

   Lime Mortar

   http://www.saveheritage.com/limemortar.htm

   http://www.saveheritage.com/limemortar.htm

2. 
   bobhallsr | Apr 22, 2002 06:50am | #8

   It is my understanding that 'soft brick' was the result of firing at a lower temperature. When coal became cheap fuel for brick kins higher temperatures were achieved and the brick was closer to being vitrified. In fact, some of the 'clinker brick', from the places closest to the flame, does look vitrified. In the old charcoal kilns, some brick got fired hotter than others and is more resistant to water absorbtion and spalling when frozen. I live near Wash, DC, and have scavenged brick from many different demo sites. Some of the old stuff wasn't worth picking up and disintegrated completely when used for walks.

   BJGardening, cooking and woodworking in Southern Maryland