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water addditions to kilns/firings

updated mon 9 apr 01


=?iso-8859-1?Q?Nisse_Holmstr=F6m?= on sun 8 apr 01


Water introduction into wood-fired kilns is no doubt an interesting , =
somewhat complex, but under the right circumstances a most rewarding =
exercise. Primarily the water will react with Carbon in the =
watergasreaction to give hydrogen and carbon-monoxide, both beeing =
excellent fuels will actually improve the combustion, give a very strong =
(hydrogen) reduction without producing any black smoke-clouds. So, from =
an environmental point of view water additions are to be recommended. =
The sintering-temperature of most ceramic compositions will be =
significantly lowered by the presence of water/steam in the kiln =
atmosphere (due to the formation of weaker hydroxyl-bonding in the =
ceramic; replacing strong SiO-SiO bonds). Reports in the litterature =
also suggests improvements in strength in some instances - the quality =
of glazes is allways improved, bubble-count/improved surfaces - lowering =
of lead-release from lead-containing glazes and/or decorations.=20
Personally I have been introducing water into my bourry-box kiln for a =
good 10 years now (up to 50 l /10 hrs firing). The water -introduction =
invariably starts at around 550 -600 degrees C and continues up to top =
temperature 1300 degrees C. The effects of water-introduction on the =
cooling-side are also astonishing - we are now talking about =
colour/surface/texture of the pieces. Basically water additions to a =
cooling kiln will act as a strong oxidicer (water constituting some 89 % =
oxygen) - when and how can be discussed and will play an important role =
on the resulting pieces.

You will find more and a more indepth treatment of the subject following =
the various links from my page - =
keep trying to improve our processes !