Monthly Archives: November 2014

1942 Alclad Marking Documentation: “The Aircraft Apprentice”

Further documentation of ALCLAD aluminum markings was published in the 1942 publication, The Aircraft Apprentice, Leslie MacGregor, Pitman Publishing Corp., 1942 (

From page 100 illustrated below: “It may be noticed that some codes are preceded by the letters ALC which signify that the alloy is covered on both sides with a coating of pure aluminum, and is known as Alclad. This coating prevents corrosion and amounts to approximately 10 per cent of the thickness of the sheet.”

image page100[Click to Enlarge]


1943 Alclad Marking Documentation: “Aircraft Production Standards”

Additional documentation of ALCLAD aluminum markings from the 1943 publication Aircraft Production Standards, Stuart Leavell and Stanley Bungay, McGraw-Hill, 1943. (

The entire text is not currently available online, but Google Books allows viewing of snippets of the work including the following: “A typical identifying code such as 24ST ALC may be used for an example. This group of numbers and letters will be found stamped repeatedly across the surface of sheet metal. Here the numerals 24 indicate a specific alloy. By referring to the table on page 253, it is possible to find the materials and their percentages used in the composition of this alloy.”


1942 Alclad Marking Documentation: “How to Do Aircraft Sheetmetal Work”

Another example of documentation of ALCLAD aluminum markings are provided in the 1942 publication How to Do Aircraft Sheetmetal Work, Carl Norcross and James D. Quinn, McGraw-Hill Book Co., Inc., 1942. (

The entire text is not currently available online, but Google Books allows viewing of snippets of the work including the following from page 50: “Alclad is used to a great extent on all-metal airplanes. Usually the sheets forming the fuselage and the wings are of Alclad. Sheets are easily identified because they are stamped “ALC” preceding the identification of the metal, for example, ALC24S-T.”


1941 Alclad Marking Documentation: “Aircraft Sheet Metal Work”

Written documentation of ALCLAD aluminum markings in 1941 is provided in Aircraft Sheet Metal Work: Bench and Repair Work, H. Edward Boggess, New York, Pitman Publ. Corp., 1941. (

From page 13 included below: “The letters AL or ALC preceding the alloy designation indicate that the material is Alclad, which means that it has been surfaced on both sides with pure aluminum.” And further on the following page, “Thus a piece of metal labeled AL-17ST-ANA would be heat-treated, Alclad dural which conforms to the Army and Navy specifications and comes from the mill at Alcoa, Tenn.”

image1[Click to Enlarge]

image2[Click to Enlarge]

Numerous photographs show the “ANA” mill/plant marking, but this photograph is the only example discovered to date showing the “ANK” mill/plant marking. (Source: National Archives,

ANK-marking[Click to Enlarge]