California brick
CALIFORNIA BRICKS


Kraftile Company

History

In 1925, when red-burning clay was discovered on the property of the K. & L. Box and Lumber Company at Niles, Alameda County, California, the owners, Homer Leash and Charles H. Kraft, formed the Kraft Clay Products Company to utilize the clay to manufacture roofing tile. K. & L. Box and Lumber Company, which manufactured cheese boxes, was a subsidiary of the Kraft Cheese Company of Chicago, Illinois. It was Homer Leash who recognized that the sawdust and wood scrap could be used to fire the clay in kilns. In February 1926, the Kraftile Company was incorporated with founders James L. and Charles H. Kraft, A. Clay Myers, president, E. Ridgeway and Homer E. Leash, directors, to manufacture glazed and unglazed tiles. The tile plant was built in 1926 at 800 Kraftile Road in Niles, CA. The office and display rooms were at 55 New Montgomery Street in San Francisco. Kraftile pioneered the process of special trimming and single-firing technique, which was known as the "Kraftile Monolithic Method" for making the most durable and uniform tiles in the industry.

After further expansions in the 1930s, the Kraftile plant manufactured a wide variety of clay products, including glazed structural wall and partition units, glazed swimming-pool-overflow gutters, patio tile, quarry tile, standard brick, Roman face brick, split pavers, enameled brick, acid-floor brick, and acid-tank block. These products were used in hospitals, schools, food product plants, factories, restaurants, stores, and public buildings throughout the country.

Local red clay was mined from a 100-foot trench, 35 feet deep, on the property by a bulldozer. The clay was mixed with barium carbonate and waste tile in a dry-pan grinding mill. It was ground to 20-mesh and the oversize was returned for regrinding. Water was added as it entered the twin screw Hummer auger where it was mixed, blended, and extruded as a block ribbon to an American wire cutting machine. The cut units were then passed to a 15-foot conveyor belt from which they were hand-loaded onto cars running on 24-inch rails. The cars were hand-trammed a short distance to carriages running on standard gauge track set normal to the narrow track. The carriages transported the cars to the entrance of the drying tunnels where they were transferred to narrow-gauge tracks running through the hot air dehydrator drying tunnels. There were eight gas-fired tunnels about 75 feet long equipped with two sets of 24-inch rails. Drying required 48 to 120 hours. These were later replaced by solar-heated driers, which cut the cost of fuel in half.

Firing took place in one of the five round down-draft 25-foot diameter kilns. Each kiln was equipped with 10 burners. Draft for the group of kilns was provided by two square stacks about 50 feet high. Bricks remained in the kilns 12 to 15 days to allow for pre-heating and cooling. Firing temperature was about 1,900 degrees F, maintained by pyrometric cone and pyrometer. In 1930, a Harrop continuous kiln was added for firing clay products.

During the depression of the 1930s, Kraftile boldly invested over $150,000 in modernization and expansion of its plant to reduce cost and remain competitive, a decision that later paid off for the company. When many ceramic manufacturing plants were closed during World War II, Kraftile was allowed to remain open with production of structural tile units and acidproof bricks. Decline in the building industry, especially for structural tile units and bricks, forced Kraftile to manufacture patio and quarry tiles, which became popular with businesses and homes.

In 1955, California Division of Mines published a tour of the plant entitled From Clay to Tile, which is reprinted here in part:

Kraftile yard
View of stacks in yard and overhead conveyor belt. Under tarpaulins
are various types of clay to be properly mixed in the batching room.

Kraftile yard
Batching room where several kinds of clay may be automatically mixed,
including local clay and clay from other parts of the state. To each
batch, barium carbonate is added to reduce efflorescence.

Kraftile yard
Clay after being batched, ground, and mixed with water, is extruded
in long bar shape onto conveyor. Shown here is clay being extruded
and cut. Wires cut 6 blocks to required tile length.

Kraftile yard
Special tiles for odd shapes and special trim are
shaped by hand, using potters wheel and hand tools.

Kraftile yard
After cutting and shaping, tile is glazed. In making glazes, a wide
variety of mineral materials is used: barite, feldspar, china clay,
and many others. Quality and color of the fired glaze are of primary
concern. Glaze may be applied to clay ware by spraying, painting, or
dipping. Here unfired clay tile is loaded onto belt for spray glazing.

Kraftile yard
Shown here is one method of glazing, utilizing
air spray. Tiles move on belt past glazer.

Kraftile yard
Loading kiln cars with unfired hollow tile that has been spray glazed.
Glazes are tested before use. One test utilizes steam under pressure in
boilers; if glaze develops cracks that show up as spidery pattern upon
being covered with ink, glaze is rejected.

Kraftile yard
Loading unfired ware into tunnel drying kiln.

Kraftile yard
After passing through drying kiln, ware may be fired in one of several
kilns. Kilns used in industry include field kilns, downdraft kilns (such
as the beehive shown here), tunnel kilns, and various types of specialty kilns.

Kraftile yard
Unloading fired tile from kiln.

Kraftile bricks were made mostly between 1933 and 1971. Face bricks were machine-extruded under vacuum to produce a dense compact body with minimum absorption and staining. The bricks were red and have smooth, unblemished surfaces. Three shapes made were the standard size, 2 5/8 by 7 5/8 by 3 5/8 inches, Roman size, 1 1/2 by 11 1/2 by 3 1/2 inches, and Brickettes, 7/8 by 1 1/4 by 11 1/2 inches, with a narrow rock-face edge on one side.

Acid-proof red floor brick were made similarly to the face brick and hard burned. They were made to withstand all acids and alkalis common to food plants. These sported the brand name "Nukem Acidproof Brick." They did not discolor and were available in either smooth or anti-slip surfaces for industrial or commercial floors.

Non-skid red split pavers measured 7 3/4 by 3 3/4 by 1 1/16 inches, with the company name and location stamped on the thin side of the brick. The split pavers were made with a non-skid feature, popular in factories and public walkways. Examples of split pavers can be seen in the first 13 Bay Area Rapid Transit stations and the sidewalks of Santa Barbara.

Modular hollow tile structural units were a major part of Kraftiles production. Both glazed and unglazed units were made with single to multiple compartments and a great variety of shapes and sizes made to order. These were used in the exterior and interior walls of buildings. The glazed or enamel faced units were popular in rooms where sanitary conditions were required, such as in kitchens, bathrooms, and hospital treatment rooms. Architectural terra cotta blocks were used on the exterior walls.

In 1950, the Kraftile plant operated five and a half days per week. The plant capacity was 1,000 tons per month. 85 were employed in the office and plant. From 1936 to 1975, Charles "Chuck" W. Kraft was the president and general manager. From 1975 to 1997, his son, James Kraft, became president and general manager. The plant closed in 1996 and the buildings were razed a few years afterwards. The clay pit was filled and the site has been developed for housing. Some of the bricks salvaged from the two stacks and some of the tile were used to make the entrance gate to the new subdivision.

Kraftile yard
View of the Kraftile Company plant, Niles, CA.

Kraftile Company Brick

Split Paver

Split paver is dark red, uniform in color. The face and sides are smooth. Two thin sides of the paver has three deep longitudinal grooves running the whole length of the brick. On one of these sides is imprinted "KRAFTILE CO NILES CALIF" in repeated fashion. Length 8, width 3 7/8, height 1 1/4 inches.

Kraftile split paver
View of the side of a Kraftile split paver displaying company name and location.

Kraftile split paver
View of the face of a Kraftile split paver.

Kraftile split paver
View of the end of a Kraftile split paver.

Split paver is orange-red to red, uniform in color. The face and sides are smooth with longitudinal short grooves giving a matte finish. Tiny specs of white subangular quartz less than 1/16 inch across are visible on the surface and constitute about 1 to 2 percent of the clay body. Some faces display a single groove running longitudinally through the center of the face, while others display transverse curved striations. Length 8 3/8, width 3 3/4, height 1 1/4 inches.

Kraftile split paver
View of the face of a Kraftile split paver at the El Cerrito Plaza BART station.

Kraftile split paver
View of the face of a Kraftile split paver at the San Leandro BART station.

Kraftile split paver
View of the face of a Kraftile split paver at the Los Angeles Mall, Los Angeles.

Patio Brick and Tile

Patio brick is brown and uniform in color. Surface is smooth. Edges are straight and sharp except for the short edges around the sides, which are rounded. Corners are sharp. Faces display curved wire-cut grooves and many show a surface undulation normal to the wire-cut giving it a wavy texture. Another variety displays faces with longitudinal grooves giving a matte texture. The interior contains about 4 percent white subangular quartz up to 1/8 inch across. The clay body is compact. This brick was made using the stiff-mud process, extruded, and wire-cut on the faces. It is a short and narrow brick with length 7 3/4, width 2 1/2, and height 1 5/8 inches.

Kraftile patio brick
View of the face of a Kraftile patio brick at the Los Angeles Mall, Los Angeles, displaying the wire-cut marks.

Kraftile patio brick
View of the smooth end of a Kraftile patio brick at the Los Angeles Mall, Los Angeles.

Kraftile patio tile
View of the face of a Kraftile patio tile at the Los Angeles Mall, Los Angeles.

Kraftile patio tile
View of the sides of a Kraftile patio tile at the Los Angeles Mall, Los Angeles.

Kraftile patio tile
View of the face of a Kraftile patio tile at the Los Angeles Mall, Los Angeles, with a matte texture.

Kraftile patio brick and tile
View of the Kraftile patio brick and tile at the Los Angeles Mall, Los Angeles.


References

Basin Research Associates, Kraftile, Fremont, California, San Leandro, California, August 1998.

California Division of Mines, From Clay to Tile, Minerals Information Service, Nov. 1955, v. 8, no. 11, p. 6-7.

Daily Review, Oct., 11, 1984, p. 29.

Davis, F.F., Mines and Mineral Resources of Alameda County, California, California State Mining Bureau, 1950, v. 46, no. 2, p. 292-293.

Dinkelspiel, Frances, Tile firm's key to survival is constant modernization, The Daily Review, October 11, 1984.

Dietrich, W.F., The Clay Resources and the Ceramic Industry of California, California State Mining Bureau Bulletin 99, 1928, p. 41.

Kraft Clay Products Co. Opens, Brick and Clay Record, v. 66, no. 9, 1925, p. 682.

Kraftile Co., A Complete Line of Enameled Clay Products, No date.

Kraftile Co., Split Pavers, 1986.

Copyright 2005 Dan Mosier

Contact Dan Mosier at danmosier@earthlink.net.