underfiring

Intentional operation of a boiler, furnace, oven, etc., at a low level.

The designer believes that by this combination of a combustion-chamber with the underfiring grate the combustion of the fuel is improved.

Underfiring of steam boilers, though not approved in this country, is very largely practised in America, […]

The state of not burning fuel at the desired level, and thus not providing heat efficiently.

In natural gas-fired boilers, gas pressure is critical to proper burner operation and efficient combustion. Variations in gas pressure may cause over- or underfiring of the boiler. […] Underfiring may cause flame instability and poor combustion efficiency due to high levels of excess air.

Gas-burner maintenance should include these measures: […] Adjust gas input if combustion testing indicates overfiring or underfiring.

Heating from below.

[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; […]

The state of being insufficiently fired or underfired.

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.