If one buys cone 6 bisque and glaze it you have NO control over how it has been bisque fired. I never had trouble with it until I did. Do you recommend refiring bisque to make sure it's had a chance to fire out impurities? I've gotten pin holes around the rim like you did! I like using holds and have had some good results. I've ruined some kiln shelves and boy that is expensive but I got smart and bought some flower pot bottoms at Loews. So far so good.
Oh the flower pot bottom is something I never thought about! Just make sure if you see any bloating or melting to stop using them( means they are getting over fired). Do you know what kind of clay the bisque fired pieces are?
I've found that clays that contain manganese tend to be more prone to pinholes (like your brown clay). In such cases, a drop and hold helps a lot. The manganese will off-gas. Dropping down about 100 degrees from the top temperature stops the volatilization process, and holding at that temperature for 30 - 45 minutes gives the glaze time to heal over. Also with a drop and hold, vs. a hold, you don't have quite the heat work because you're not holding at top temp. Any hold will increase heat work, so firing schedules may need adjusting to account for that. I have not found the higher bisque temperature to help, unless the glaze defect is from too thick of a coat of glaze or the bisqueware absorbing too much water and not drying out. Higher bisque will cause less absorption. Another thing I did in the past was to sub Ferro Frit 3134 for up to half of the Gerstley Borate on certain glazes. That won't help people who use premixed glaze though. Thanks for posting this. I would love to hear your thoughts on this.
Yeah I agree that high bisque temps don’t really work as well. It is an option that I have heard so I thought I would suggest it. I do agree that the manganese causes issues as well. My kiln is hard to program a drop and hold ( it is fairly small and basic)so unfortunately I have never tried that solution. Thanks for suggesting it though!
@@storiesnstoneware I have a manual (kiln sitter) kiln. I have to guess at the temperature drop, but have had luck with waiting about 15 - 20 minutes after the kiln shuts off, then restarting and turning my bottom two switches to medium, top low.
Thank you for alleviating my concerns about refiring our pieces haha My daughter and i have just gotten into clay and our glaze application was less than perfect 🤣
Unfortunately I'm in a community studio, so I have no control of firing schedules. My pin hole problems seem to be related to using a grogged clay, which, when trimming leaves lots of little gouges in the clay. Burnishing the gouges away seemed to help a bit. Also heavy decoration with underglaze seemed to help a bit. I've been experimenting with non-grogged clay, I did a batch of mugs with porcelain and they came out fine. Now I'm trying simple b-mix fingers crossed.
Yeah I find that groggy clay or speckled clay tend to have that problem, fitting glazes and with causing pinholes. I had a speckled clay I had to give up on cause there were not enough glaze I use that worked. You could try renting the kiln space to try and do your own program if that is allowed. I did that with my clear glaze with the community studio I have.
Crazing is still one I’m trying to work through and avoid myself. I’ve mostly only succeeded by switching clays. Or I use liner glazes on the inside that I know are stable and food safe and use the glazes that tend to craze on the outside. I will link to some other videos you might find helpful though! th-cam.com/video/pjS_87A7h5U/w-d-xo.htmlsi=Ird9CFGiAA0a4jAe th-cam.com/video/-LTd6sOFikA/w-d-xo.htmlsi=o6KBP-ztXgsO14I2
thank you, i've been looking for advice on how to fix pinholes and this is perfect!
no problem! happy to help!
Thanks
If one buys cone 6 bisque and glaze it you have NO control over how it has been bisque fired. I never had trouble with it until I did. Do you recommend refiring bisque to make sure it's had a chance to fire out impurities? I've gotten pin holes around the rim like you did! I like using holds and have had some good results. I've ruined some kiln shelves and boy that is expensive but I got smart and bought some flower pot bottoms at Loews. So far so good.
Oh the flower pot bottom is something I never thought about! Just make sure if you see any bloating or melting to stop using them( means they are getting over fired). Do you know what kind of clay the bisque fired pieces are?
I've found that clays that contain manganese tend to be more prone to pinholes (like your brown clay). In such cases, a drop and hold helps a lot. The manganese will off-gas. Dropping down about 100 degrees from the top temperature stops the volatilization process, and holding at that temperature for 30 - 45 minutes gives the glaze time to heal over.
Also with a drop and hold, vs. a hold, you don't have quite the heat work because you're not holding at top temp. Any hold will increase heat work, so firing schedules may need adjusting to account for that.
I have not found the higher bisque temperature to help, unless the glaze defect is from too thick of a coat of glaze or the bisqueware absorbing too much water and not drying out. Higher bisque will cause less absorption.
Another thing I did in the past was to sub Ferro Frit 3134 for up to half of the Gerstley Borate on certain glazes. That won't help people who use premixed glaze though.
Thanks for posting this. I would love to hear your thoughts on this.
Yeah I agree that high bisque temps don’t really work as well. It is an option that I have heard so I thought I would suggest it. I do agree that the manganese causes issues as well. My kiln is hard to program a drop and hold ( it is fairly small and basic)so unfortunately I have never tried that solution. Thanks for suggesting it though!
@@storiesnstoneware I have a manual (kiln sitter) kiln. I have to guess at the temperature drop, but have had luck with waiting about 15 - 20 minutes after the kiln shuts off, then restarting and turning my bottom two switches to medium, top low.
Thank you for alleviating my concerns about refiring our pieces haha
My daughter and i have just gotten into clay and our glaze application was less than perfect 🤣
No problem! Happy to help.
Unfortunately I'm in a community studio, so I have no control of firing schedules. My pin hole problems seem to be related to using a grogged clay, which, when trimming leaves lots of little gouges in the clay. Burnishing the gouges away seemed to help a bit. Also heavy decoration with underglaze seemed to help a bit. I've been experimenting with non-grogged clay, I did a batch of mugs with porcelain and they came out fine. Now I'm trying simple b-mix fingers crossed.
Yeah I find that groggy clay or speckled clay tend to have that problem, fitting glazes and with causing pinholes. I had a speckled clay I had to give up on cause there were not enough glaze I use that worked. You could try renting the kiln space to try and do your own program if that is allowed. I did that with my clear glaze with the community studio I have.
@@storiesnstoneware That's a good idea. I might ask around for kiln availibility.
Can you do a video to avoid crazing pls. I love your explanation here and seem to be getting crazing specifically with Coyote glaze.
Crazing is still one I’m trying to work through and avoid myself. I’ve mostly only succeeded by switching clays. Or I use liner glazes on the inside that I know are stable and food safe and use the glazes that tend to craze on the outside. I will link to some other videos you might find helpful though!
th-cam.com/video/pjS_87A7h5U/w-d-xo.htmlsi=Ird9CFGiAA0a4jAe
th-cam.com/video/-LTd6sOFikA/w-d-xo.htmlsi=o6KBP-ztXgsO14I2
God info, thank you!
Thanks! I hope it helps you!