Thomas Gainsborough is thought to have coined the phrase 'pot boiler' in reference to mediocre works of art made solely to bring in some money for the
bare necessities of life. When asked why he painted so many portraits, he replied 'to keep the pot boiling' and these portraits thus became the 'pot boilers'.
Potboiler is also the name given to a novel written for monetary gain rather than for any artistic value, usually by an already respected author.
"The Pot-Boiler" is a story written by Edith Wharton and published in Scribner's Magazine in December 1904. It is about a poor, asthmatic sculptor, Casper, and his sister Kate who looks after him. Because of his illness money becomes scarce and there is a debate about whether an artist should ever sacrifice his convictions and produce art just for the money. Kate thinks this is too great a sacrifice to make, but is prepared to sacrifice herself by marrying someone she does not love so that Casper can afford to live, rather than marry the man she prefers but who paints portraits merely for money.
The full text can be found on-line at http://etext.lib.virginia.edu/toc/modeng/public/WhaBoil.html
Pot boilers are stones which were used for heating water and for cooking. The earliest pot boilers date from mesolithic times (from 8300 BC in Britain). In the Stone Age the only means of containing fluids was in animal skins or wooden vessels. These obviously could not be placed over a fire to heat the contents so stones or pebbles were heated in the fire and then dropped into the liquid until the desired temperature was reached.
Pot boilers are found on archaeological sites alongside debris such as charcoal and ash, in what is known as a burnt mound. They are often associated with areas of ritual burial and may have been used in preparation of the funeral meal or in cleansing and preparing the body.
By the end of the Bronze Age (from 2000 BC - 700 BC) people were able to work metal into sheets for buckets and pans and cooking became a much simpler process.