Please note

Because of the lack of published trowel and masonry tool histories, the information here is based on other sources that may be less reliable and certainly are incomplete. These include eBay and tools that I purchase myself that are the starting points for my research. I will write what I know as I learn it. If what you read here interests you, please check back often and look for revisions and corrections. Scanned catalogs are either mine or by Rose Antique Tools and used with permission, and are on Google Docs as pdf files. A few are links to other websites. Your photos and information are welcome. Please click on any picture to enlarge it. Comments are welcome, but any with links will be deleted as possible spam.

Thursday, June 9, 2016

Harmon S. Palmer, Concrete Block Machine Inventor

Harmon S. Palmer 1905
Harmon Sylvanus Palmer is the American inventor credited with the concrete block machine. Palmer patented a concrete block mold in 1887, his first block machine in 1899, a concrete block wall with rectangular voids in 1901, another machine in 1903, and other patents followed. However, Palmer lost his technological advantage by being overly controlling with his inventions. He failed to realize that there were many possible designs for block machines and many entrepreneurs ready to make them, some of which predated his patents. He also restricted his customer's sales territories, a tactic that concrete trade publications editorialized against. Another self-inflicted problem was that his blocks were too large and heavy for one man to carry and lay. Palmer blocks were 24 or 32 inches long, 9 inches high, and 4 to 16 inches wide.

An exponential annual increase in cement demand and production after 1890 ensured a ready market for block machines. In response to many competing machines flooding the market, Palmer aggressively protected his patents, suing anyone infringing on them. Many Harmon S. Palmer Hollow Building Block Co. advertisements threatened competing manufacturers, their customers, and even the owners of buildings built with other block machines. It appears that he moved to Washington DC to better prosecute his legal claims. When he won a key lawsuit, he was unprepared to meet anticipated demand and contracted with another machine manufacturer in 1906. Later the same year, he lost on appeal because other designs existed before his. He never regained his initial lead with block machines.

Harmon S. Palmer was born 9 Mar. 1843 in Michigan, and died 1 Mar. 1931 in Washington DC. He and his wife Nellie E. had sons Floyd and Clyde. The sons lived with their parents, didn't marry, and worked for the business. In 1910 Palmer lived at 1450 Girard St., originally named  Binney St. While that house is gone, across the street a stately double house is built with his blocks.
Harmon S. Palmer advertisement, 1904
US cement production 1890-1908 


  1. I have some building blocks that say on them and HS Palmer building block Pat 1901 66 Maiden Ln., New York I was just wondering if these blocks are worth any value. Thank you