Michelle on tue 21 jun 05
Hi all, I'd like a little input on a low fire issue. I'll try to make a long story short.
Here is the background: I manage two studio's. One does mostly low fire and the other does just a little low fire. We use the same overglaze ( c109 Mayco, fire to 06/05) and the same underglazes (Amaco). At " Studio A" we do have low fire clay and at "Studio B" they use a cone 6-9 stoneware (I have already brought up the whole glaze/clay fit issue to them). When I fire them I had been using a small cone 04 since it seemed to fire perfectly to large cone 05 throughout the kiln. Most of the studio's I have worked at did similar firings with no issues.
The issue: Someone in "Studio B" insists that we have to fire to small cone 06. Their reasoning is that some of the underglazes burn out,bleed and run(the overglaze) at the temp. we are currently firing at (small 04, large 05). Now I know people who have used some of the same underglazes at cone 6 and not had them burn out or bleed. Also she is the only person who seems to have this issue.
The question: Am I nuts? Is she possibly putting the glaze on too thick? Not waiting for the underglaze to dry completely? Not putting enough underglaze on?
Any input would be most helpful.
Thanks
Michelle
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Valice Raffi on sun 26 jun 05
Michelle,
I frequently low fire mixed loads (bisque and glaze) to ^04 with no
problems, so I don't think the temp is the issue.
Burn out can be due to too high a firing, but at ^04, the most likely cause
is insuficient underglaze. If there is a light application of underglaze,
the color sometimes gets "sucked up" by the clear. If she wants strong
color, she needs to apply three coats of opaque underglaze, maybe she's
using the translucents?
Bleeding is caused by:
1) not allowing the underglaze to dry completely (I often put the
underglazed piece back in a bisque firing to "set" the underglaze).
2) "scrubbing" the clear (it should be applied softly in a flowing coat
with a wide, soft brush)
3) getting the piece too wet when dipping (maybe she's brushing after dipping?)
The running is because the clear glaze is applied too thickly.
Have her read the application instructions on the jars! Maybe she hasn't
done that yet.
Good luck!
Valice
Potters Council member
Las Cruces, NM
>The issue: Someone in "Studio B" insists that we have to fire to small
>cone 06. Their reasoning is that some of the underglazes burn out,bleed
>and run(the overglaze) at the temp. we are currently firing at (small 04,
>large 05). Now I know people who have used some of the same underglazes at
>cone 6 and not had them burn out or bleed. Also she is the only person
>who seems to have this issue.
>
>The question: Am I nuts? Is she possibly putting the glaze on too thick?
>Not waiting for the underglaze to dry completely? Not putting enough
>underglaze on?
>
>Any input would be most helpful.
>
>Thanks
>
>Michelle
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