Discoveries
Discovery of the P.B.Co. Marked Brick
By Dan L. Mosier
When George L. Kennedy showed me some red bricks marked with P.B.Co. that he had purchased at a rock materials yard in Riverside County, California, in 2015, it was a great surprise. He was told that the bricks came from Los Angeles and that was all he knew. A brick with this marking was a new discovery for us. The brick was a typical-looking red sand-molded common brick, but it was marked on one of the faces with raised letters inside a rectangular frog. The abbreviations hinted of a brick company name. This article demonstrates how we were able to determine the probable maker of the P.B.Co. brick.
It was natural to guess which brick companies in the Los Angeles area had those initials. The oldest was the Pasadena Brick Company that made bricks in 1888 at Pasadena. There was a Pacific Brick Company that operated yards at Pasadena and Los Angeles from 1896 to 1900 by the same Simons people that later changed its name to the Simons Brick Company. Another Pacific Brick Company operated a brickyard at Santa Monica from 1936 to 1946. The Pomona Brick Company at Pomona had a brickyard from 1890 to 1965. There were also other brick companies with those initials in other parts of California and beyond. So, which of these brick companies could have made that brick?
I began by examining the interior of the brick as I usually do for sand-molded red common bricks, because the exterior surface, which is often covered by a coating of sand, does not reveal much about the possible provenance of these types of bricks. But the problem that was immediately encountered with the P.B.Co. bricks was with the scarcity of broken surfaces to examine the interior clay body. I did not want to break the brick in half. The interior clay body was exposed shallowly in only a few places, mainly on the broken corners and edges of the bricks. The largest area of exposure was about an inch in diameter. This revealed that the clay body was composed of a sandy clay with moderate amounts of pores. About 10% of the clay contained white quartz, white granitic rocks, and yellow clay spots, ranging from 1/16 to 1/4 inch across. Though most of the rocks were in the 1/16 to 1/8 inch range, they could be identified with a 10-power hand lens.
Two sizes of bricks were measured. One is 8 3/8 x 3 7/8 x 2 1/2 inches and the other 7 7/8 x 3 1/2 x 2 1/4 inches. The exterior surface has a coating of sand giving the brick a pale brownish red color. The frog in the larger brick measures 6 x 2 x 1/8 inches; its name spans 4 5/8 inches and is 1 1/8 inches in height. The frog in the smaller brick measures 5 5/8 x 1 3/4 x 1/8 inches; its name spans 4 1/8 inches and is 1 inch in height. For this identification, I decided to use the larger brick which provided the most information. I also decided to begin the research with the brickyards in the Los Angeles area to see if a match might be found.
Data for the unknown P.B.Co. brick along with bricks from other possible brickyards in the Los Angeles area are shown in the following tables for comparison.
Table 1. Exterior Features.
Brickyard
Brick Size
Color
Sand-coating
Years
P.B.Co.
pale brownish red
yes
?
Pomona Brick Co.
pale brownish red
yes
1890-1965
Pacific Brick Co. Pasadena yard
orange red
yes
1896-1900
Pacific Brick Co. Los Angeles yard
orange red, pale red
yes
1898-1900
Table 2. Interior Clay Body Components
Brickyard
Clay Texture
Pores
Rocks (decreasing order)
Volume %
Rock Size
P.B.Co.
sandy clay
moderate
quartz, granitic rock, yellow clay
10
Pomona Brick Co.
sandy clay
moderate
quartz, granitic rock, yellow clay
10-15
Pacific Brick Co. Pasadena yard
sandy clay
low
quartz
5
1/16 – 1/2
Pacific Brick Co. Los Angeles yard
sandy clay
high
quartz, yellow clay, iron oxides
20
Absent from the tables are the bricks from the Pasadena Brick Company and the Pacific Brick Company at Santa Monica, for which none were available to examine and compare for this study. Data for the brick from the Pomona Brick Company came from its bricks in the YMCA building in Pomona (Mosier, 2007). Data for the brick from the Pacific Brick Company at Pasadena came from the bricks in the Union Garage at Pasadena (Mosier, 2008). The Union Garage was built in 1907 using brick from the Pasadena yard of the Simon Brick Company, formerly known as the Pacific Brick Company prior to 1900. Similarly, a brick made at the Simons Brick Company yard at Boyle Heights, Los Angeles, provided the data from that brickyard (Mosier, 2010). In the table, it can be seen that the P.B.Co. brick matches best with the brick made by the Pomona Brick Company in color, brick size, sand-coat, clay texture, and rocks. But further verification of the rocks was needed by checking the geology of the Pomona brickyard site.
The brickyard of the Pomona Brick Company was located at the corner of 9th Street and Buena Vista Avenue, where the clay occurred in a Holocene alluvial fan deposit (Gay and Hoffman, 1954). Nearby are heavily eroded Cretaceous tonalite igneous rocks, Miocene Puente Formation sandstone and siltstone, and Miocene Glendora rhyolite and dacite volcanic rocks (Morton and Miller, 2006). Therefore these rock types can be expected to be found as clasts in the Pomona bricks. Quartz and the granitic rocks seen in the Pomona bricks are probably derived from the tonalite igneous rocks. The yellow clay is probably an alteration product of the feldspars eroded out of the igneous rocks.
The brick from the Pacific Brick Company at Pasadena also has a number of matches, such as brick size, sand coat, clay texture, and pores. However, it has a low percentage of quartz in the clay. More importantly, granitic rocks and yellow clay are absent. This is because the Pleistocene alluvial deposits at Pasadena (Yerkes and Campbell, 2005), where the clay was mined, appear to lack the rocks that were seen in the P.B.Co. brick. The surrounding bedrock exposures are dominantly Miocene sandstone, siltstone, and conglomerate. These are the rock types that are more likely to be seen in the Pasadena bricks. Based on that, the P.B.Co. bricks could not have come from Pasadena.
Another supporting evidence for the Pomona Brick Company came from the ledgers of the Western Clay Machinery Company, which dealt in brickmaking machinery at Monterey Park, California, thanks to Josh Higgins who had sent me this information. The ledgers revealed that in 1922, Pomona Brick Company ordered 20 maple six-paneled brick molds from the Lancaster Iron Works. Two of the panels were to contain the letters P.B.Co. The panels were to measure 8 3/4 x 4 3/16 x 2 1/2, which, compared to our P.B.Co. brick, fit well, indicating about a 3/8-inch shrinkage in the length and width resulting from firing in the kiln. This indicated that the Pomona Brick Company marked one-third of its bricks with the initials P.B.Co.
The clay pit at the Pomona brickyard was worked from 1896 to 1943, when it was exhausted (Mosier, 2007). During this period, the brickyard used the soft-mud process in making its bricks (Gay and Hoffman, 1954). The soft mud process means that the clay was put in molds to form the bricks. After 1943, the clay was obtained from another pit a half mile south and the stiff-mud process was used to make bricks (Gay and Hoffman, 1954), which would look quite different than the P.B.Co. bricks. The stiff-mud process means the clay was put into a machine that extruded a clay column that was cut into bricks, usually by a wire, thus forming wire-cut bricks. The Pomona Brick Company supplied most of its bricks locally, but some were sent as far away as San Diego (Mosier, 2007).
The P.B.Co. brick was made by the soft-mud process, so that would fit into the 1896-1943 period for the Pomona brickyard. If the Pomona Brick Company began marking its bricks in 1922, as indicated in the Western Clay Machinery Company ledgers, then we could refine the years for the P.B.Co. brick to 1922-1943. This could be verified and further refined by searching in the Pomona area for buildings built between 1922 and 1943 with P.B.Co. marked bricks. The local geology at Pomona also supports the quartz, granitic rock, and yellow clay found in the brick. Thus, the P.B.Co. brick was probably made at the Pomona brickyard between 1922 and 1943.
References
Gay, T.E., and Hoffman, S.R. Mines and Mineral Resources of Los Angeles County, California. California State Mining Bureau, California Journal of Mines and Geology, v. 50, no. 3-4, 1954, p. 467-709.
Morton, D.M., and Miller, F.K. Geologic Map of the San Bernardino and Santa Ana 30′ x 60′ Quadrangles, California. U.S. Geological Survey Open-File Report 2006-1217, 2006.
Mosier, Dan L. Pacific Brick Company, Pasadena. California Bricks, calbricks.netfirms.com, 2008.
Mosier, Dan L. Pomona Brick Company. California Bricks, calbricks.netfirms.com, 2007.
Mosier, Dan L. Simons Brick Company, Plant Number 1, Boyle Heights, Los Angeles. California Bricks, calbricks.netfirms.com, 2010.
Yerkes, Robert F. and Campbell, Russell H. Preliminary Geologic Map of the Los Angeles 30′ x 60′ Quadrangle, Southern California. U.S. Geological Survey Open-File Report 2005-1019, 2005.
Citation: Mosier, Dan L. Discovery of the P.B.Co. Marked Brick. California Bricks, https://californiabricks.com, 2022.
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