Santa Cruz County History - Making a Living



The Laguna Limekilns: Bonny Doon
by Robert W. Piwarzyk

[This article is excerpted from a manuscript titled, "The Laguna Limekilns: Bonny Doon," pp. 44-45. The maps, drawings, and photos of the manuscript are not included on this site. The manuscript is copyrighted 1996 by the author. It is used here with permission.]

Glossary

Arch Brick:
wedge-shaped brick used in building an arch. Usually an arch brick is wedged such that it appears truncated when viewing it from the end. A wedge brick can be truncated when viewing it from the face or side, and either can be used in building an arch.

Bat or Brick Bat:
a piece of brick. Usually half a brick containing either the right or left hand end.

Brick:
a solid masonry rectangular block made from clay and/or shale and burned (or fired) in a kiln. The plural of brick may be bricks or brick.

Building Lime:
a higher grade (or quality) of lime than that used for agriculture, or other uses such as manufacturing paper, paint, or soap; refining sugar; or processing hides for leather.

Common Brick:
any brick designed for building purposes. Usually refers to softer and less expensive bricks.

Firebrick:
brick designed to withstand high temperatures. Made with special fireclays. Most common standard size is 2 1/2" x 4 1/2" x 9" but is produced in various sizes and shapes.

Frog:
a depression in the face of the brick made by a panel placed in the bottom of the mold. Lettering is placed on this panel to make either a raised or depressed letter in the frog.

Kiln:
an oven-like compartment built to contain the heat around the item to be calcined, cooked, baked, burned, or fired. A "pot" kiln (or field kiln) is usually built with an open top to facilitate loading the kiln. "Patent" kilns were metal designs that were patented, and came ready to assemble. Thomas Bull had one near his pot kiln. Other patent kilns were "continuous," as the limestone moved through the kiln while the fuel (usually oil carried by steam) burned continuously. These were more efficient, but were hard to operate with high grade ore which crumbled more easily and jammed the kiln. The time saved in reducing the load/unload cycle might be lost when a kiln jammed. Limekilns are like updraft furnaces or ovens. Some sources use the singular, kiln, to denote the site, even though more than one kiln exists. Use of the words "kill," and "kills," may derive from the archaic spelling "killn."

Limestone:
any number of differing ores usually containing 50% or more of calcium carbonate, (CaCO3).

Quicklime:
also called lump lime, caustic lime, or unslaked lime. This was the name given the lime (CaO) as it was removed from the kilns and packed into barrels. It was "quick" to stick to the skin. Handling the product is hazardous, as it is caustic, takes water from the flesh, and gives off heat. This heat is enough to char wood, and warehouses and schooners shipping lime were known to catch fire.

Refractory Mortar:
also called fire mortar. A finely ground refractory material which becomes plastic when mixed with water, and is suitable for use in laying refractory brick (i.e. firebrick).

Slaked Lime:
quicklime has an avidity for water which is added intentionally to hydrate, or slake, the lime causing it to crumble into powder. Slaking quicklime produces CaOH and is the first step in making lime products such as milk lime, whitewash, plaster (lime plaster), stucco, mortar (lime mortar), cement, and concrete. Thus lime that has not been slaked is said to be "unslaked lime." When the water is taken from the atmosphere, it is said to be "air slaked," or "dry slaked." When water is added to hydrate it, it is said to be "wet slaked."

Tufa:
also known as travertine, this rock formation occurs when dissolved calcium carbonate precipitates out of solution. This is similar to the process that creates flowstone, and stalagmites and stalactites.

Vitrification:
a condition resulting from kiln temperatures high enough to fuse grains and close the pores of a clay mass, making it impervious to water.

Bibliography

View similarly tagged articles:

brick buildings, building construction, kilns

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