An Imperial Size sheet of paper ~ 30 inches x 22 inches
Over the centuries various sizes of paper have been made and popularized in different countries. In Great Britain there was a whole system called Imperial Measures ~ gallons ~ chains ~ ounces. Many of the Imperial units remain in use ~ although more carefully defined than being 'the area of a field that can be ploughed in a day'. Most countries now use the ISO216 and related systems [113021], although manufacturing machinery and established traditions ~ and vocabulary ~ take a long time to wear out ~ '...take a length of two by one...'
Nowadays Imperial Size Paper refers to paper measuring 22" x 30" ~ 559mm x 762mm ~ with an aspect ratio of 1.3636.
One reason is that ~ I surmise ~ Imperial is about as large a handmade sheet as can conveniently be made by one person [120729]. There may be other reasons ~ I am a bit stuck for any at present ~ help gratefully received!
Imperial sheets of paper are still made ~ and sold ~ for artist's use, although Half Imperial or Quarter Imperial are more commonly sold as convenient sizes for paintings ~ and for shipment by mail. Machines designed to make that size of paper are still in existence ~ will they ever wear out? If artists wish to buy it ~ why not continue to make it? Most artists' materials are also available in ISO216 sizes.
In the picture an A4 cutting mat lies on top of a sheet of Imperial Size paper. An A2 mat cutting lies underneath the end of it. Both mats are fractionally larger than the quoted 'A' size. Imperial is a little shorter than an A1 sheet
An ISO A1 sheet measures 59cm wide ~ Imperial is 60cm wide
an ISO A1 sheet measures 84cm long ~ Imperial is 76cm long
an Imperial sheet is 8cm short of an A2 sheet.
When discussing Half Imperial it is the full Imperial sheet area that is halved ~ only one dimension is halved ~ 22"x15".
When discussing Quarter Imperial it is the full Imperial sheet area that is quartered ~ both dimensions are halved ~ 15"x11".
