California brick

Union Brick Company


Union Brick Co. ad

In 1904, John Willard Rice, born in Iowa on January 10, 1879, established a brick manufacturing firm at the foot of 23rd and Pierce streets, San Diego. The Union Brick Company was organized with John Rice as president, William C.S. Cross as vice-president, and Eva E. Rice as secretary and treasurer. John and Eva Rice were married in 1907. Surface clay was obtained on the property to make common brick until about 1912, when the company moved its operations to Rose Canyon, 10 miles north of San Diego. The Union Brick Company purchased the former property and plant of the Sunnyside Brick and Tile Company, consisting of 220 acres of patented land. The plant's leaning smokestack was a landmark for many years for motorists passing by on Highway 101.

The clay mined at Rose Canyon was part of the Rose Canyon shale member of the Eocene La Jolla formation. The first pit mined was near Elvira Station on the Santa Fe Railroad. The plant was also located there until the pit was abandoned in 1941. The plant was moved about 2.5 miles south where the company opened a second pit on the west side of Rose Canyon. The West pit closed in 1947, and a third pit was opened on the east side of the canyon. The East pit was worked until the operations closed in 1965. Clay was mined during the 1920s by Fordson Tractors and scrapers, which dumped the material into a chute at the bottom of the canyon.

In 1925, the plant consisted of a dry pan and two brick presses for making dry-pressed bricks. They also made sand-molded common brick. Operations described in 1963 stated that the clay was reduced to minus 1/4-inch in a primary crusher, ground in a dry pan, and delivered to a screw-type pugging and extrusion machine. Barium carbonate was added to the water to reduce scumming in the finished brick. A vacuum of 24 pounds per square inch was used to remove any air trapped in the mix. The continuous bar of clay extruded from the pugging machine was cut by wire cutter into bricks. Different dies were used to produce the various shaped bricks. It took five to six weeks for the wet bricks to dry in the sun or a shorter time in fan-ventilated sheds and hot air dryers. After drying, the bricks were fired in field (scove) kilns for six days or for 24 hours in a shuttle kiln. Oil was used for the fuel and the plant was powered by electricity. The plant had a capacity of 80,000 bricks per eight-hour period.

The bricks produced by the Union Brick Company varied over the years by the change in location of its clay pits and the type of brick processes used. The bricks made at its 1904 to 1912 plant in downtown San Diego was probably a sand-molded common red brick. After 1912, red common dry-pressed brick and building tile were added using Rose Canyon shale. The sand-molded brick made in Rose Canyon very likely differed from the earlier San Diego sand-molded brick, which I have no example yet to describe. It is not known exactly when the company began to produce the different shaped bricks. These include the smooth or scratch face brick Standard (8 x 3 3/4 x 2 1/2), Norman (11 1/2 x 3 1/4 x 2 1/2), Oversize (11 1/2 x 3 1/4 x 3 1/2), and Brik-Blok (11 1/2 x 5 1/2 x 3 1/2 and 15 1/2 x 7 1/2 x 3 1/2).

The Union brick plant closed about 1965. The buildings and the leaning smokestack were eventually razed and the area has been restored back to its natural state in Marian Bear Memorial Park.

Union Brick

Common brick is orange to red and mostly uniform in color. The edges are straight and dull. Corners are dull or broken. Sides and ends are mostly unmarked with minor cracks. Top face is uneven, highly pitted, with large pits up to 1 1/2 inches across, and has a longitudinal strike. Stack indentations may be displayed on the faces. Bottom face is flat with the initials of the company centered in a beveled, rectangular frog. The letters are raised, thin, and span 3 1/2 inches. The block letters U, B, and C are 1 1/8 inches high. The lower case "o" is 7/8 inch high. The frog measures 6 inches long, 2 inches high, and 1/8 inch deep. Example of an unmarked frog shown below indicates that not all bricks were marked. Occasional clasts are visible on the surface composed of subrounded granitic rock or pink feldspar, up to 3/4 inch across, and black iron oxide spots up to 1/8 inch across. The interior clay body is the same color as the surface and is porous (10 percent) and contains about 5 percent clasts. This brick was made using the sand-molded, soft-mud process. Length 8 1/4, width 3 7/8 wide, height 2 3/8 inches.

marked face of the Union brick
View of the marked face of a red Union brick.
Photo courtesy of Ron Anjard

marked face of the Union brick
View of the marked face of an orange Union brick in La Jolla.

side view of the Union brick
View of the side of the Union brick.

unmarked frog of the Union brick
View of the unmarked frog of the Union brick. Donated by George L. Kennedy.

side view of the Union brick
View of the side of the unmarked Union brick.

rough top face of the Union brick
View of the rough top face of the unmarked Union brick.


Federal Census Records, 1910.

Kennedy, George L., personal communication and brick donor, 2014.

San Diego City Directories 1910-1966.

Tucker, W.B., San Diego County, Mining in California. California Mining Bureau Report, v. 20, no. 4, p. 368-374.

Tucker, W.B., San Diego County, Mining in California. California Mining Bureau Report, v. 21, no. 3, p. 325-382.

Tucker, W.B., and Reed, C.H., Mineral Resources of San Diego County, California Journal of Mines and Geology, v. 35, no. 1, p. 8-55.

Weber, F. Harold, Jr., Geology and Mineral Resources of San Diego County, California, California Division of Mines and Geology County Report 3, 1963, p. 61-68.

Copyright 2007 Dan Mosier

Contact Dan Mosier at