Conrad Krebs on mon 8 sep 08
Hello,
I'm new to raku having fired only a few times. Does under fired raku
look just like over fired raku? I had a firing where glaze was running
off the piece (suggesting over fired) while at the same time large
blisters were forming and popping on the gaze surface (suggesting under
fired).
Thanks, Conrad
John Hesselberth on tue 9 sep 08
Hi Conrad,
Glazes can blister from being under or over fired. It all depends on
exactly what is in the glaze and where the various components give
off gases.
Regards,
John
On Sep 8, 2008, at 9:45 PM, Conrad Krebs wrote:
> Hello,
>
> I'm new to raku having fired only a few times. Does under fired raku
> look just like over fired raku? I had a firing where glaze was running
> off the piece (suggesting over fired) while at the same time large
> blisters were forming and popping on the gaze surface (suggesting
> under
> fired).
>
> Thanks, Conrad
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
Conrad Krebs on tue 9 sep 08
Hi John, thanks for responding.
The glaze is "Raku Burst" from Laguna. The glaze contains, among other
things, copper compounds (6%) and titanium dioxide (2%) according to the
material safety data sheet. My setup has the burner under the shelf, two
half shelves really set up on bricks above the burner chamber with a
slight separation between the shelves. I did change the loading this
time however. The objects I am firing are bases for lanterns, so they
are flat with a hole in the center for the light. I had been firing them
flat on metal stilts. This time however I hung each vertically from its
center hole on a wire suspended between two posts (I did this to get rid
of stilt marks). I arranged the loading radially around the periphery of
the kiln with the bases facing the kiln wall (Picture a lollipop. the
stick represents the path the burner flame took. The lantern bases were
arranged radially around the rim of the lollipop).
Conrad
John Hesselberth wrote:
> Hi Conrad,
>
> Glazes can blister from being under or over fired. It all depends on
> exactly what is in the glaze and where the various components give
> off gases.
>
> Regards,
>
> John
> On Sep 8, 2008, at 9:45 PM, Conrad Krebs wrote:
>
>> Hello,
>>
>> I'm new to raku having fired only a few times. Does under fired raku
>> look just like over fired raku? I had a firing where glaze was running
>> off the piece (suggesting over fired) while at the same time large
>> blisters were forming and popping on the gaze surface (suggesting
>> under
>> fired).
>>
>> Thanks, Conrad
>
> John Hesselberth
> http://www.frogpondpottery.com
> http://www.masteringglazes.com
>
>
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