Pat Walker on tue 1 jan 08
The recipe I have for ocean blue seems to come out brown, not blue.
Does someone know if I made a mistake somewhere? (cone 6)
EPK 5.4
feldspar 25.3
laguna borate 20
nepheline syenite 22
silica 18
RIO 1.8%
rutile 2.8%
copper carb 3.5%
Donald Burroughs on wed 2 jan 08
Replace RIO with a 1/2% cobalt carb.
According to my colourant combo charts in reduction RIO + Rutile induces
ochre browns. In oxidation they induce tan like colours. If you add copper
carb like your receipe you will probably get warm brown-greens. Replace
the RIO outright as I suggest will have you leaning towards warm blue-
greens textured = cobalt carb.+ copper carb.+ rutile in reduction. Warm
blue-green in oxidation, notwithstanding your base ingredient reactions.
Remember test,test,and more testing.Sigh.
Regards, Don Burroughs
moira clinch on thu 3 jan 08
Hi,
When using stoneware blue glazes I have often found they come out brown
if applied too thinly, or bisque high-fired and less absorbant. The same
can happen with a couple of green glazes I have used as well. If
students in my classes are doing their own glazing without supervision,
they don't always stir the glaze fully, particularly those that tend to
settle solidly in the bucket. If they have been left a while,t hese need
a good "blunging". with the glaze mixer. A spoonful of epsom salts (
magnesium sulphate) can help, but don't overdose. This helps keep the
glaze in suspension, but add too much and it rapidly goes to lumpy
custard.!
Moira Clinch (www.claywork.co.uk)_
Pat Walker wrote:
> The recipe I have for ocean blue seems to come out brown, not blue.
> Does someone know if I made a mistake somewhere? (cone 6)
> EPK 5.4
> feldspar 25.3
> laguna borate 20
> nepheline syenite 22
> silica 18
> RIO 1.8%
> rutile 2.8%
> copper carb 3.5%
>
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