75% of the 2.8 billion pencils made in the US are painted yellow (Steve Ritter "Pencils & Pencil Lead", Chemical & Engineering News, Volume 79, Number 42 page 35, 15 October 2001). Pubs.acs.org
Pencil grades vary "depending upon the manufacturer, when the pencils are made, and the source of graphite and clay. One analyst found that graphitic carbon content, for example, to vary from about 30 to about 65 in a variety of different pencils bearing the same designation." Petroski 1990, p. 229 Petroski, Henry (1990). The Pencil: A History of Design and Circumstance. New York: Alfred A. Knopf. ISBN0-394-57422-2.
Conté used integer numbers that started at 1, with higher numbers indicating softer leads, while Thoreau used higher numbers to designate harder leads (Petroski 1990, p. 157). It is believed that Thoreau developed independently his method of mixing clay and graphite, and his use of numbers to designate grades is evidence that he was at least aware of Conté methods and tried to reverse engineer them.
Thoreau offered pencils graduated from 1 to 4 in the mid-1800s (Petroski 1990, p. 119), see also John H. Lienhard (1989). "Thoreau's Pencils". The Engines of Our Ingenuity. Episode 339. NPR. KUHF-FM Houston. Transcript. uh.edu Petroski, Henry (1990). The Pencil: A History of Design and Circumstance. New York: Alfred A. Knopf. ISBN0-394-57422-2. Petroski, Henry (1990). The Pencil: A History of Design and Circumstance. New York: Alfred A. Knopf. ISBN0-394-57422-2.
Eagle Pencil Company applied for the trademark Mirado in 1947 (US Trademark 71515261). It is common belief that this was an attempt to disassociate the pencil brand from Japan, as one of the meanings of Mikado is emperor of Japan.
Petroski states that Eagle Pencil Company changed the name after the Attack on Pearl Harbor. Petroski, Henry (1990). The Pencil: A History of Design and Circumstance. New York: Alfred A. Knopf. ISBN0-394-57422-2.
Zumdahl, Steven S. & Zumdahl, Susan A. (2008). "No lead pencils". Chemistry. Belmont, CA: Cengage Learning. p. 343. ISBN978-0-547-12532-9.
"Pencils". Borrowdale Points. 10 February 2015. Archived from the original on 23 November 2015. Retrieved 23 November 2015.
brandnamepencils.com
Mikado/Mirado pencils were originally made by Eagle Pencil Company – today Berol – but can also be found today under the trademark Papermate and Sanford as Sanford owns Berol and the trademark Papermate Brandnamepencils.comArchived 29 September 2007 at the Wayback Machine Mirado Pencil
cbsnews.com
O'Shaughnessy, Lynn (22 July 2010). "Why Are Pencils Yellow?". CBS News MoneyWatch. Retrieved 24 July 2021.
This testing method is approved by the ISO as standard ISO 15184:1998 Paints and varnishes – Determination of film hardness by pencil test ISO.orgArchived 26 October 2017 at the Wayback Machine. See pra-world.comArchived 29 September 2007 at the Wayback Machine for a description of the test. Unfortunately the hardness of pencils is not standardised. For this reason the standard specifies various brands of pencils that are to be used in this test.
This testing method is approved by the ISO as standard ISO 15184:1998 Paints and varnishes – Determination of film hardness by pencil test ISO.orgArchived 26 October 2017 at the Wayback Machine. See pra-world.comArchived 29 September 2007 at the Wayback Machine for a description of the test. Unfortunately the hardness of pencils is not standardised. For this reason the standard specifies various brands of pencils that are to be used in this test.
Conté used integer numbers that started at 1, with higher numbers indicating softer leads, while Thoreau used higher numbers to designate harder leads (Petroski 1990, p. 157). It is believed that Thoreau developed independently his method of mixing clay and graphite, and his use of numbers to designate grades is evidence that he was at least aware of Conté methods and tried to reverse engineer them.
Thoreau offered pencils graduated from 1 to 4 in the mid-1800s (Petroski 1990, p. 119), see also John H. Lienhard (1989). "Thoreau's Pencils". The Engines of Our Ingenuity. Episode 339. NPR. KUHF-FM Houston. Transcript. uh.edu Petroski, Henry (1990). The Pencil: A History of Design and Circumstance. New York: Alfred A. Knopf. ISBN0-394-57422-2. Petroski, Henry (1990). The Pencil: A History of Design and Circumstance. New York: Alfred A. Knopf. ISBN0-394-57422-2.
This testing method is approved by the ISO as standard ISO 15184:1998 Paints and varnishes – Determination of film hardness by pencil test ISO.orgArchived 26 October 2017 at the Wayback Machine. See pra-world.comArchived 29 September 2007 at the Wayback Machine for a description of the test. Unfortunately the hardness of pencils is not standardised. For this reason the standard specifies various brands of pencils that are to be used in this test.
Mikado/Mirado pencils were originally made by Eagle Pencil Company – today Berol – but can also be found today under the trademark Papermate and Sanford as Sanford owns Berol and the trademark Papermate Brandnamepencils.comArchived 29 September 2007 at the Wayback Machine Mirado Pencil
