Perrygraf Enamel Coating Calculator Slide Rule for Armco

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This blue, tan, and white cardboard rule consists of an envelope held together by six metal rivets and a paper slide. The rule calculates the weight of an enamel coating, given the area of a metal sample; the surface area of metal, given its thickness and weight; and the weight of enamel per square foot of surface coated, given the weight of enamel used, the thickness of the metal sample, and the weight of the metal.
Perrygraf Corporation of Maywood, Ill., made this instrument (copyrighted in 1941) for the American Rolling Mill Company of Middletown, Ohio. ARMCO produced and enameled coils of sheet steel at plants in Middletown and Ashland, Ky. Since 1999, the company has been part of AK Steel. For more on Perrygraf, see 1979.3074.03.
Reference: "American Rolling Mill Company," Ohio History Central: An Online Encyclopedia of Ohio History, July 1, 2005,
Currently not on view
date made
Perry Graf Corporation
Physical Description
metal (part material)
paper (overall material)
overall: .2 cm x 22 cm x 7.6 cm; 3/32 in x 8 21/32 in x 3 in
ID Number
catalog number
nonaccession number
Credit Line
Transfer from Smithsonian Institution Libraries
Rule, Calculating
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Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History