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Damp bricks - how to dry them?  RSS feed

 
Posts: 36
Location: northern VT
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Collecting materials for my first rmh, I obtained ~80 bricks and 15 firebricks salvaged from a fireplace which had been built in the 70's. They've been outside uncovered on pallets for a few months. This means, I assume, that they're not completely dry.

How can I prepare them for use ie dry them, and how will I know they're ready to use?  I don't currently have electricity or an oven, though if necessary I can impose on friends or relatives.
 
Posts: 217
Location: US, East Tennessee, north of Knoxville
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I was in a similar situation, had to clean (under running water and scrubbing with a brush) a lot of brick. Afterwards the bricks were placed (and spaced well apart) lined up on planks raise up off the ground, and left to air dry for several days under a makeshift shed roof.

The bricks are ready to use when they are dry to the touch. They are going to get wet when mortaring them in place, so they don't have to be kiln dried by any means. But if you're concerned about firing a freshly built wet stove, do what the professional heater masons do. Build small consecutive "curing" fires to keep some warmth in the brick, for up to a day or so, to dry the masonry slowly, before having a really hot raging full temperature burn.
 
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I learned decades ago that the proper condition for bricks to lay up is "saturated surface-dry". You want the brick surface to grab some water out of the mortar immediately so the wall firms up, but you want a reservoir to keep the mortar from drying completely too fast, as that interrupts the curing of the mortar and weakens it.

Of course, it may be that modern hard bricks are impervious enough that their moisture condition is irrelevant; but you are probably not using modern hard bricks but old soft brick.
 
Glenn Herbert
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Note that bricks from the 1970s may be hard brick and not suitable for RMH core construction. Do they leave a red streak when rubbed across concrete? If so, fine. If not, they might not have the thermal shock resistance for core use.
 
Susana Smith
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Location: northern VT
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Thanks so much Byron and Glenn!  I will both air-dry and use small fires.

The info about testing soft vs hard is what I was going to look for next, now if I need more I can test them on-site. 
 
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