Fred Parker on wed 4 nov 09
This is a "for what it's worth" post...
As I mentioned in an earlier post in this thread I recently fired a few
sample items made with Highwater's "Helios" grolleg porcelain, said by th=
=3D
e
company to work over the range from ^7 to ^11. The kiln has now cooled a=
=3D
nd
I have inspected the results.
The items were three or four tea bowls. A couple of them are unmodified
Helios with a clear glaze inside and out. The third is Helios "agateware=
=3D
"
made from Helios containing various amounts of Mason stains.
Obviously I have not done absorption testing because I did not include an=
=3D
unglazed test tile and all items are glazed. However, everything LOOKS
good! Each shows translucency when held in front of a lamp, although the=
=3D
y
seem to be slightly less translucent than Standard 365 fired the same.=3D20=
=3D
Having no caliper to measure wall thickness I don't know whether this is =
=3D
a
result of the firing temperature or what seems to be a slightly thicker w=
=3D
all.
I definitely like the color of the clay itself. The unglazed foot rings =
=3D
and
bases showing the bare porcelain are considerably whiter/brighter than
Standard 365. Most buyers probably would not pick up on this difference =
=3D
but
the best word I can find to describe it is just "pretty." I like to look=
=3D
at it.
It was controller-fired to what I want to be ^6 and what always turns out=
=3D
to
be a very robust ^6. The ^7 was about 2/3 of the way down (My controlle=
=3D
r
has a mind of its own and over time we have learned to tolerate each othe=
=3D
r's
idiosyncrasies...) The firing profile includes normal firing to temperat=
=3D
ure
(with the last 300 degrees at 108/hr), a ten minute hold, shutdown/coolin=
=3D
g
to 1900 and then slow cooling at 125/hr to 1400 where the kiln is turned =
=3D
off.
I am not working with porcelain currently but when I do more I will try t=
=3D
o
remember to make some test tiles and do an absorption test.
I have no complaints about Helios' working characteristics. It is smooth=
=3D
and buttery and, for the items I have made (tea bowls) it dries without
having to be coddled. I dry it the same way I dry white stoneware. Like=
=3D
most porcelains it does not like being saturated with excess water, so
throwing has to proceed without a lot of restarts and extra pulls. Havin=
=3D
g
said this I should add that it is not particularly finicky in this regard=
=3D
--
any more than, say cone 5 "B" mix.
The only "oh, crap!" physical characteristic I noticed might well be my
technique instead of the clay, but it SEEMED to have a very good memory o=
=3D
f
stress induced while still leather hard. I trim tea bowls on a porcelain=
=3D
chuck. Generally, depending on how moist the chuck and the pot it I migh=
=3D
t
sponge either or both with a damp sponge for adhesion to the chuck. WHen=
=3D
I
remove the trimmed piece I tend to have to "wiggle" the piece a bit to ge=
=3D
t
it to break loose, then for some I lift from the chuck at an angle. Afte=
=3D
r
bisque firing I noticed several tea bowl rims with flat sides. They were=
=3D
circular going into the bisque kiln and flat coming out. All I can figur=
=3D
e
is I must have stressed them coming off the trim chuck. As I said, it mi=
=3D
ght
have been the way I did it, and not the clay at all.
That's my story and I'm sticking to it,
Fred Parker
Lorraine Pierce on wed 4 nov 09
Hi Fred..some time ago I glazed a Helios bowl and test tile with The M^6G
Majolica glaze. The results were beautiful when I took them from the kiln
however over time, in real kitchen use, the bowl has developed severe craze
flaws and now shivering due to poor glaze/body compatibility. Too bad..it i=
s
a really nice body to throw. As a rule I never use anything but a ^6 clay
body and ^6 glaze together. I knew better! Lori P. in Orange Park, Fl.
On Wed, Nov 4, 2009 at 10:20 AM, Fred Parker wrote:
> This is a "for what it's worth" post...
>
> As I mentioned in an earlier post in this thread I recently fired a few
> sample items made with Highwater's "Helios" grolleg porcelain, said by th=
e
> company to work over the range from ^7 to ^11. The kiln has now cooled a=
nd
> I have inspected the results.
>
> The items were three or four tea bowls. A couple of them are unmodified
> Helios with a clear glaze inside and out. The third is Helios "agateware=
"
> made from Helios containing various amounts of Mason stains.
>
> Obviously I have not done absorption testing because I did not include an
> unglazed test tile and all items are glazed. However, everything LOOKS
> good! Each shows translucency when held in front of a lamp, although the=
y
> seem to be slightly less translucent than Standard 365 fired the same.
> Having no caliper to measure wall thickness I don't know whether this is =
a
> result of the firing temperature or what seems to be a slightly thicker
> wall.
>
> I definitely like the color of the clay itself. The unglazed foot rings
> and
> bases showing the bare porcelain are considerably whiter/brighter than
> Standard 365. Most buyers probably would not pick up on this difference
> but
> the best word I can find to describe it is just "pretty." I like to look
> at it.
>
> It was controller-fired to what I want to be ^6 and what always turns out
> to
> be a very robust ^6. The ^7 was about 2/3 of the way down (My controlle=
r
> has a mind of its own and over time we have learned to tolerate each
> other's
> idiosyncrasies...) The firing profile includes normal firing to
> temperature
> (with the last 300 degrees at 108/hr), a ten minute hold, shutdown/coolin=
g
> to 1900 and then slow cooling at 125/hr to 1400 where the kiln is turned
> off.
>
> I am not working with porcelain currently but when I do more I will try t=
o
> remember to make some test tiles and do an absorption test.
>
> I have no complaints about Helios' working characteristics. It is smooth
> and buttery and, for the items I have made (tea bowls) it dries without
> having to be coddled. I dry it the same way I dry white stoneware. Like
> most porcelains it does not like being saturated with excess water, so
> throwing has to proceed without a lot of restarts and extra pulls. Havin=
g
> said this I should add that it is not particularly finicky in this regard
> --
> any more than, say cone 5 "B" mix.
>
> The only "oh, crap!" physical characteristic I noticed might well be my
> technique instead of the clay, but it SEEMED to have a very good memory o=
f
> stress induced while still leather hard. I trim tea bowls on a porcelain
> chuck. Generally, depending on how moist the chuck and the pot it I migh=
t
> sponge either or both with a damp sponge for adhesion to the chuck. WHen=
I
> remove the trimmed piece I tend to have to "wiggle" the piece a bit to ge=
t
> it to break loose, then for some I lift from the chuck at an angle. Afte=
r
> bisque firing I noticed several tea bowl rims with flat sides. They were
> circular going into the bisque kiln and flat coming out. All I can figur=
e
> is I must have stressed them coming off the trim chuck. As I said, it
> might
> have been the way I did it, and not the clay at all.
>
> That's my story and I'm sticking to it,
>
> Fred Parker
>
Veena Raghavan on wed 4 nov 09
Hi Fred,
I normally fire Helios to cone 9 or cone 10, and there have been problems
with warping in bowls, especially if they are thin. From what I have
understood, both from other members of my studio and on Clayart, this has b=
een a
problem for many with Helios-rims warping, so you are not alone.
Veena
In a message dated 11/4/2009 11:31:06 AM Eastern Standard Time,
fhparker@YAHOO.COM writes:
> The only "oh, crap!" physical characteristic I noticed might well be my
> technique instead of the clay, but it SEEMED to have a very good memory o=
f
> stress induced while still leather hard. I trim tea bowls on a porcelain
> chuck. Generally, depending on how moist the chuck and the pot it I migh=
t
> sponge either or both with a damp sponge for adhesion to the chuck. WHen
> I
> remove the trimmed piece I tend to have to "wiggle" the piece a bit to ge=
t
> it to break loose, then for some I lift from the chuck at an angle. Afte=
r
> bisque firing I noticed several tea bowl rims with flat sides. They were
> circular going into the bisque kiln and flat coming out. All I can figur=
e
> is I must have stressed them coming off the trim chuck. As I said, it
> might
> have been the way I did it, and not the clay at all.
>
> That's my story and I'm sticking to it,
>
>
>
VeenaRaghavan@cs.com
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