Every time a kiln is fired a microscopically thin layer of oxide is
added to the surface of the element, and a similar amount of the element
core is diminished. This eventually leads to there being more oxide than
element core and firings begin to take longer and longer! Curiously this
layer of oxide also acts as a protection from the highly corrosive
atmosphere in a firing Kiln.
With a partial or positive reduction firing the layer of oxide can be
stripped from the element, probably shortening its life.
There are 2 ways of dealing with this potential hazard, one is to fire
the pieces in a fireclay box or Saggar, sealing the lid with clay/sand
mix or bits of ceramic fibre, the other is to follow a very smokey or
reduction firing with a short firing to red heat (say 700oC) of the
empty kiln to re-establish the oxide layer. As a matter of interest it
is also a good idea to fire the kiln empty each time new elements are
fitted to give them the same protection.

Steve
Bath
UK


In article , Monika Schleidt
writes


Lcdumas wrote:

Something that makes a nice surface is to embed hamster litter into the clay
and then let it burn out in the kiln.

Linda D

But isn't it bad for your electric kiln to create all this smoke in it? It's ok
if you fire with gas or oil, but i was told, not to do it in an electric kiln.

Monika

--
Monika Schleidt

www.schleidt.org/mskeramik



--
Steve Mills
Bath
UK