Bruce Girrell on mon 30 may 05
Does anyone out there happen to lnow if there is a flux that is particularly
effective in melting rutile/ilmenite?
I just fired a glaze test series that included varying amounts of rutile and
ilmenite. The results all show that I am simply not melting the rutile and
ilmenite particles. Examination under a microscope shows that the edges of
the rutile particles are not even being attacked. They look almost identical
to particles prior to firing.
The recipe that I am using is
Custer 41
Silica 33
Dolomite 12
Whiting 7
OM4 7
Rutile 4.5
which yields a unity formula of
CaO 0.52 Al2O3 0.33 SiO2 4.05
MgO 0.24 TiO2 0.01
K2O 0.17
Na2O 0.08
Fe2O3 0.01
Si:Al = 12.20
The formula falls nicely within the cone 10 limit provided by Rhodes except
for the fact that Rhodes includes 0.1-0.3 Boron.
The formula is similar to what John Britt provides for a rutile blue formula
except that Silica is too high. The glaze does fire to a satin appearance,
not glossy, so maybe decreasing the silica might help, but would that
improve the melt on the rutile?
I would appreciate any suggestions regarding how to improve the melt for
rutile.
Thanks,
Bruce "feeling quite humbled again" Girrell
URL Krueger on mon 30 may 05
On Monday 30 May 2005 08:36 am, Bruce Girrell wrote:
> Does anyone out there happen to lnow if there is a flux
> that is particularly effective in melting
> rutile/ilmenite?
>
> The results all show that I am simply not melting the
> rutile and ilmenite particles.
Bruce,
Why do you expect they should melt?
What is your purpose in adding rutile to a glaze?
When I add rutile or titanium dioxide to a glaze it is to
produce a variegation. It has always looked to me in
closeups that this effect was produced by fine particles
that tend to accentuate flow patterns.
Do you have a different reason for adding rutile?
--
Earl K...
Bothell WA, USA
Craig Martell on mon 30 may 05
Bruce wanted to know:
>Does anyone out there happen to lnow if there is a flux that is particularly
>effective in melting rutile/ilmenite?
Hello Bruce:
In the past a lot of people have used colemanite and gerstley borate. I
use ferro frit 3134. I have an rutile overglaze that's basically a
balanced, durable, although very active glaze. I add 20% rutile and it all
gets melted. This is for application over tenmoku glazes. Anyway, I use
about 15% 3134. Your glaze could probably use much less. Just run a line
blend.
regards, Craig Martell Hopewell, Oregon
Earl Brunner on wed 1 jun 05
From: "Bruce Girrell"
To: "Clayart"
Subject: RE: Best flux for rutile?
Date: Wed, 1 Jun 2005 16:39:49 -0400
Ron Roy wrote:
>It was obvious that the illmanite was melting in the clay matte
because the
>specks were not only brown but bigger than the black specks in the
other
>glazes.
The glaze tests that I ran varied from 3 to 7% rutile and from 1 to 5%
ilmenite. The ilmenite did show signs of melting in exactly the manner
that
you describe, but the rutile granules showed no sign of melting
whatsoever.
I suspect that the additional iron in the ilmenite made the difference.
>So the key to melting granular illmanite - or rutile - would seem to
be an
>over fluxed glaze.
This is one of those cases where the glaze was working and something
changed, so now I have to build a new version of the glaze. I hate to
make
the glaze too glossy and runny because it is a really nice glaze, but
I've
lost the color so I have to do something. Adding boron is the easiest
change, as I can easily calculate the numbers to add appropriate
amounts to
the test batches that I have already made.
>Perhaps reducing the silica will get you there.
I suspect, however that this may be the direction that I actually have
to go
to preserve the qualities that I want and this will require a whole new
set
of mixes. C'est la vie. I'll try the boron first, then I'll do a Currie
test
to test the silica issue.
Thanks for your input,
Bruce
Earl Brunner
e-mail: brunv53@yahoo.com
Ron Roy on wed 1 jun 05
Hi Bruce,
I used a cone 8 matte clay when I was teaching years ago - which had some
granular illmanite in it - which melted to a brown speck. In all the other
glazes in which the granular illmanite was tried - it remained as a black
speck.
It was obvious that the illmanite was melting in the clay matte because the
specks were not only brown but bigger than the black specks in the other
glazes.
So the key to melting granular illmanite - or rutile - would seem to be an
over fluxed glaze.
Perhaps reducing the silica will get you there.
RR
>Does anyone out there happen to lnow if there is a flux that is particularly
>effective in melting rutile/ilmenite?
>
>I just fired a glaze test series that included varying amounts of rutile and
>ilmenite. The results all show that I am simply not melting the rutile and
>ilmenite particles. Examination under a microscope shows that the edges of
>the rutile particles are not even being attacked. They look almost identical
>to particles prior to firing.
>
>The recipe that I am using is
>
>Custer 41
>Silica 33
>Dolomite 12
>Whiting 7
>OM4 7
>
>Rutile 4.5
>
>which yields a unity formula of
>
>CaO 0.52 Al2O3 0.33 SiO2 4.05
>MgO 0.24 TiO2 0.01
>K2O 0.17
>Na2O 0.08
>Fe2O3 0.01
>
>Si:Al = 12.20
>
>The formula falls nicely within the cone 10 limit provided by Rhodes except
>for the fact that Rhodes includes 0.1-0.3 Boron.
>
>The formula is similar to what John Britt provides for a rutile blue formula
>except that Silica is too high. The glaze does fire to a satin appearance,
>not glossy, so maybe decreasing the silica might help, but would that
>improve the melt on the rutile?
>
>I would appreciate any suggestions regarding how to improve the melt for
>rutile.
>
>Thanks,
>
>Bruce "feeling quite humbled again" Girrell
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
| |
|
