patrick terjak on sun 2 may 99
Oh Yes!
The variability of chemicals & Glaze results!!!
Concerning the purity of Red Iron Oxide - my best guess is that
Spanish
Red Iron Oxide usually is not more than 70% purity - the availability
of
higher percentages of purity of Red Iron Oxide is out there!
I
recently purchased from Davens Pottery Supply in Atlanta(Chamblee) GA
some
of their Special Red Iron - the helpful person on the phone told me
that
it is 99% pure (I think it is more like 80% purity), but my Tomato
Red
Glaze is coming out just swell - I have used 90% pure RIO & 99% pure
RIO
in Iron Red glazes before - as well as in chun blue glazes - to the
best
of my recollection it was always purchased from Ceramic Color &
Chemical
- or some such name - outside of Pittsburgh PA (maybe New Brighton)
Anyway-
We always had to purchase at least $250 worth of chemicals from them
they
do not mess around - But, the more pure the RIO the more orangey-red
in
color it is! - Looks more toxic - also the resultant glaze is much
brighter
in color - and does tend more to the orange in an RIO saturate red
glaze
recipe - any recipe should work the same - thicker application tends
toward
the murky brown result many of you are mentioning - hope this helps!!
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