underfiring

1. (also attributively) Heating from below.Examples: "[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."; "In an underjet coke oven, a distribution system for delivering a combustion-medium into the underfiring system of said coke oven, comprising: a header-pipe having a plurality of outlets therealong; pipe-connections at a region so remote from the active combustion zone of the underfiring system of the oven as to be unaffected by the heat of active combustion in the combustion zone, for delivering said combustion-medium from said header-pipe outlets to different points in conduit means of said coke-oven underfiring system; […]"; "Convert liquid heaters from underfiring to immersion or submersion heating"Antonyms: overfiringalsoattributiveuncountable

2. (ceramics) The state of being insufficiently fired or underfired.Examples: "Hence it is, I must suppose, that while more effects could be produced with rose if one could only be sure of the fire, yet carmine is the more serviceable, as one is at so much less risk of loss from overfiring, which is more common than underfiring."; "The brick color which you describe as the result of your carmine after firing is generally due to underfiring and a second fire, stronger, will remedy this, but if this is caused by the painting either laid on too thick or spoiled by other colors, there is no remedy."; "After either underfiring (4 minutes at 1,450° F), normal firing (4 minutes at 1,575° F), or overfiring (6 minutes at 1,750° F), the specimens were deenameled with molten sodium hydroxide."Antonyms: overfiringuncountable