Ron Roy on thu 2 sep 99
There is no such thing as over reduction - either the iron is reduced to
FeO or not or partially.
The condition described as "results that indicate over reduction (blackish
copper reds" is really a form of carbon trapping. So far as I can tell a
later reduction should eliminate this - those of you with experience - it
that right?
Just so we can start with good information and arrive at solutions faster.
RR
>----------------------------Original message----------------------------
I don't experience your problem of
>over-reduction. My reds stay red, mostly. I try to maintain 0.6-0.65 from
>cone 7 to cone 10 (if I go below this , e.g., 0.4, I will get under-reduction),
>then fully oxidize for about 20 minutes at the end just before shutting down
>the kiln.
>
>> My results indicate inadequate reduction (iron-rich glazes didn't melt
>> completely by the flue, copper reds were mottled green and red). When I
>> lock the oxyprobe on the first steady reading I can get (about .65 or so) I
>> get results that indicate overreduction (blackish copper reds) and at .78
>> or so, tin reduced to metal crystals in the glaze (pretty neat looking,
>> except the copper was blah reddish black).
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
David Hendley on fri 3 sep 99
I think dark, muddy copper reds are the result of too much
reduction. I call it over-reduction.
I think it can happen from a too-early reduction (carbon
trapping), as Ron says, but I also think heavy, billowing-
smoke reduction late in the firing can also give you poor,
muddy color, as can reduction-cooling (striking) when the
load was fired-up in reduction.
The operative word here is THINK. After years of trying
to really understand how copper reds work, the above
are just my best guesses.
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
----- Original Message -----
From: Ron Roy
To:
Sent: Thursday, September 02, 1999 11:18 AM
Subject: Re: over reduction???
| ----------------------------Original message----------------------------
| There is no such thing as over reduction - either the iron is reduced to
| FeO or not or partially.
|
| The condition described as "results that indicate over reduction (blackish
| copper reds" is really a form of carbon trapping. So far as I can tell a
| later reduction should eliminate this - those of you with experience - it
| that right?
|
| Just so we can start with good information and arrive at solutions faster.
|
| RR
|
|
| |
|
