English

Noun

underfiring ‎(uncountable)

1. Heating from below. (Also used attributively.)
   • 1856 May 1, William Kemble Hall, “On the Causes of Explosions of Steam Boilers”, in Journal of the Franklin Institute of the State of Pennsylvania for the Promotion of the Mechanic Arts, volume XXXI, number Third Series, page 299:

     [W]hile there were fully as many under-firing as tube-firing boilers, at work, the majority of explosions took place in boilers of the latter class, and they almost invariably commenced with the collapse of the fire flue.

2. Intentional operation of a boiler, furnace, oven, etc., at a low level.
   • 1934, Wilbert J. Huff, “Gaseous Fuels during 1932 and 1933”, in A Survey of American Chemistry, volume VIII, New York, N.Y.: Chemical Catalog Company for National Research Council, OCLC 2394622, page 339:

     The lowered demand for coke during the depression, the necessity of maintaining the gas output and the ready availability of liquefied petroleum gas for underfiring led to the conversion of the North Shore coke plant of Becker ovens at Waukegan, Illinois, to this fuel. […] The thermal efficiency of the underfiring was about five per cent lower and somewhat more attention was required to keep the ovens in balance.

3. The state of not burning fuel at the desired level, and thus not providing heat efficiently.
   • 2012, Eugene Silberstein, Residential Construction Academy: HVAC, 2nd edition, Clifton Park, N.Y.: Delmar, ISBN 978-1-285-22526-5, page 680:

     Damaged or clogged oil piping between the tank and the furnace will result in reduced fuel flow to the burner. This can cause burner underfiring, which is identified by: / Reduced heating capacity / High oxygen readings during combustion test / Low stack or flue temperature / Low temperature rise (temperature differential) across the heat exchanger […]

4. (ceramics) The state of being insufficiently fired or underfired.
   • 2003, Mark Burleson, The Ceramic Glaze Handbook: Materials, Techniques, Formulas, Rev. edition, New York, N.Y.: Lark Books, ISBN 978-1-57990-439-5, page 85:

     Underfiring results when the kiln doesn't reach the cone temperature at which your glaze matures. Underfiring can be caused by improper calibration of kiln sitters or computer controllers, firing a kiln too quickly so that not enough time is allowed for the glazes to develop properly, or by kiln elements that are worn and need to be replaced.

Verb

underfiring

1. present participle of underfire

Antonyms

• overfiring