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subject: re: copper reds

updated mon 3 sep 07


Ivor and Olive Lewis on sat 1 sep 07

I understand one way of explaining Copper Red relates to the nature of =
the Copper Ion, in solution in the glaze, and the way ions agglomerate =
then precipitate into entities that interact with light. If insufficient =
time is allowed for the reaction the glaze remains colourless.
What does Tichane tell us ? What has Weyl to say ?
All the best,=20
Ivor Lewis.
South Australia.

John Britt on sun 2 sep 07


I guess I have a different take on copper reds. I think that they are easy
to achieve!

I am a little late on is subject but I, too, became confused with all this
talk of soaking and down firing with copper reds. In my mind, this is not
the main consideration when trying to get copper reds.

The main consideration is to have a good recipe, put the glaze on thick
enough and reduce early enough. If you are afraid of running then use drip
trays. Then, if you don=92t get reds then consider the cooling cycle.

While reading the replies to the original question I came away with the
conclusion that soaking and down firing was the =93trick=94. It is probably
just me but I think that some of the confusion is the terminology.

Coppers reds are not created on the cooling cycle they =93manifest=94 on the=

cooling cycle. Unless the red has been created early in the heating cycle
they will never manifest. It is like planting a seed, or being pregnant.
The plant or baby is not =93created=94 on the day it sprouts or is born it i=
created on the day of conception, and manifested on the day of its birth.
This is the same with copper reds. And it is an important distinction
because if you focus on the time period of the copper red manifesting
during cooling you will do all kinds of things that may or may not help
you to get reds.

This is easy to test for your self. Fire in full oxidation and then cool
slowly. You will not get any reds. You could do another test, fire in full
oxidation and then =93strike=94 the kiln for an hour or so at 1500 F =96 188=
0 F
and see if you get reds. You will. But they will only create reds on the
top millimeter of the glaze. This results in a different looking red than
those created on the heating cycle. (you can easily sand through the layer
of red. I have photos of this in my book.)

Another test that others spoke of was reducing at cone 012 to peak and
then pulling draw tiles and noticing that the red forms on the cooling
cycle. So if you pull a tile at peak and cool it quickly the tile will be
colorless or some shade of green. Then reheat it in a bisque it will be
turn red. This it because the glaze it needs time to form red and you have
allowed that in the reheating. But if you don=92t "create the red" by
reducing at cone 012 then no amount of reheating will produce red.

Hope this helps,

John Britt