How do I date a Durham Duplex?

By the firm name on the stamp. Durham Razor Company is the earliest era, Durham-Enders comes before 1942, and Durham-Duplex Co. of Sheffield carries the line to 1970, which is the whole span recorded for the firm.

The maker's archive

Durham Duplex razors.

Durham Duplex is a rare case where the chronology comes out of the stamp itself, because the firm changed its name and kept the mark. There are no serial numbers and no date codes; what is dated is the firm, and the name on the razor places it inside the firm’s own history.

Country: USA
Active since
Coverage: 1908–1970 · 1 code systems
Dating tier: Codes only
In the archive: 0 series · 1 code systems · 1 models
Years documented: 1908–1970

Eras

1908–1925

Durham Razor Company

The original name, taken on with the purchase of the Alfred Williams Company, and the name the earliest razors carry.

to 1942

Durham-Enders

The firm was renamed Durham-Enders before 1942, and razors carrying that name sit after the first era.

to 1970

Durham-Duplex Co.

By 1970 the firm is Durham-Duplex Co. of Sheffield, the closing era of the whole operation, which runs from 1908 to 1970.

What dates this maker

The firm name on the stamp — Durham Razor Co., Durham-Enders, or Durham-Duplex — which selects the era.
The city on the razor — Mystic, Connecticut, or Sheffield — which follows the same sequence.
The whole period of operation, 1908 to 1970, as the outer bound when only a general mark is present.
The blade type, the Duplex being a proprietary double-edged blade, which identifies the razor rather than dating it.

Watch out

The name gives an era and not a year: two of the three firm names carry no printed years at all in the source.
A Duplex razor needs its own proprietary blade, so a modern blade in it is a modification and says nothing about the age of the razor.

1 Durham Duplex models are catalogued with their production years, specs and safety notes.