Jump to content


Photo
- - - - -

Tiny Pinhole Clusters


  • Please log in to reply
13 replies to this topic

#1 Plattypus

Plattypus

    Advanced Member

  • Members
  • PipPipPip
  • 33 posts
  • LocationNew Jersey

Posted 09 June 2010 - 07:39 PM

Hi Everyone, Hope someone has an idea for me.... I recently started using some Spectrum 4/6 glazes on my stoneware. I have been overlapping 2 to 3 colors and I love the finish but I have been getting sporadic pinholes and clusters of tiny pinholes. The stoneware is Standard 306 but it is usually being fired at 04 instead of the c4/10 range printed on the box (long story) Does anyone think that the disparity between the bisque temp and the glaze temp is causing the pinholes? I have glaze fired at c5 and c4 with no change in the pinholes... What about the thickness of the glaze? I'm wondering if the pinholes are due to slight thicknesses in the glaze coverage... I would welcome any thoughts

#2 Christine

Christine

    Advanced Member

  • Members
  • PipPipPip
  • 106 posts
  • LocationUK

Posted 10 June 2010 - 02:38 PM

Hi Everyone, Hope someone has an idea for me.... I recently started using some Spectrum 4/6 glazes on my stoneware. I have been overlapping 2 to 3 colors and I love the finish but I have been getting sporadic pinholes and clusters of tiny pinholes. The stoneware is Standard 306 but it is usually being fired at 04 instead of the c4/10 range printed on the box (long story) Does anyone think that the disparity between the bisque temp and the glaze temp is causing the pinholes? I have glaze fired at c5 and c4 with no change in the pinholes... What about the thickness of the glaze? I'm wondering if the pinholes are due to slight thicknesses in the glaze coverage... I would welcome any thoughts



Hello Plattypus...
I had a pinholing problem some years ago and was advised to give a half-hour soak once the kiln reached temperature - it worked for me. It's also the case that clay which is underfired at bisque may retain moisture which could also explain pinholes forming during a higher temperature glaze firing
Hope this helps
Christine

#3 Plattypus

Plattypus

    Advanced Member

  • Members
  • PipPipPip
  • 33 posts
  • LocationNew Jersey

Posted 11 June 2010 - 06:36 PM

Hello Plattypus...
I had a pinholing problem some years ago and was advised to give a half-hour soak once the kiln reached temperature - it worked for me. It's also the case that clay which is underfired at bisque may retain moisture which could also explain pinholes forming during a higher temperature glaze firing
Hope this helps
Christine
[/quote]

Thanks for your reply Christine... My firing knowledge is really basic. I use an electric kiln with a kiln sitter. I set the starting percentage, the hours it takes to reach 100% and I'm off. I know how to do an initial soak but not in the middle or back end. Can anyone tell me how to follow Christine's suggestion?

#4 Plattypus

Plattypus

    Advanced Member

  • Members
  • PipPipPip
  • 33 posts
  • LocationNew Jersey

Posted 15 June 2010 - 07:31 PM

just FYI... I thinned the dried layers of glaze over run with a small dry sponge and fired on 4 rather than 5 (had a lot of movement with 6) and I may have those pinholes on the run.. they are better but not gone %100

#5 Dee Sota

Dee Sota

    Newbie

  • Members
  • Pip
  • 9 posts

Posted 19 June 2010 - 01:33 PM


Hi Everyone, Hope someone has an idea for me.... I recently started using some Spectrum 4/6 glazes on my stoneware. I have been overlapping 2 to 3 colors and I love the finish but I have been getting sporadic pinholes and clusters of tiny pinholes. The stoneware is Standard 306 but it is usually being fired at 04 instead of the c4/10 range printed on the box (long story) Does anyone think that the disparity between the bisque temp and the glaze temp is causing the pinholes? I have glaze fired at c5 and c4 with no change in the pinholes... What about the thickness of the glaze? I'm wondering if the pinholes are due to slight thicknesses in the glaze coverage... I would welcome any thoughts



Hello Plattypus...
I had a pinholing problem some years ago and was advised to give a half-hour soak once the kiln reached temperature - it worked for me. It's also the case that clay which is underfired at bisque may retain moisture which could also explain pinholes forming during a higher temperature glaze firing
Hope this helps
Christine



#6 Dee Sota

Dee Sota

    Newbie

  • Members
  • Pip
  • 9 posts

Posted 19 June 2010 - 01:36 PM


Hi Everyone, Hope someone has an idea for me.... I recently started using some Spectrum 4/6 glazes on my stoneware. I have been overlapping 2 to 3 colors and I love the finish but I have been getting sporadic pinholes and clusters of tiny pinholes. The stoneware is Standard 306 but it is usually being fired at 04 instead of the c4/10 range printed on the box (long story) Does anyone think that the disparity between the bisque temp and the glaze temp is causing the pinholes? I have glaze fired at c5 and c4 with no change in the pinholes... What about the thickness of the glaze? I'm wondering if the pinholes are due to slight thicknesses in the glaze coverage... I would welcome any thoughts



Hello Plattypus...
I had a pinholing problem some years ago and was advised to give a half-hour soak once the kiln reached temperature - it worked for me. It's also the case that clay which is underfired at bisque may retain moisture which could also explain pinholes forming during a higher temperature glaze firing
Hope this helps
Christine



#7 Dee Sota

Dee Sota

    Newbie

  • Members
  • Pip
  • 9 posts

Posted 19 June 2010 - 01:39 PM

Please forgive this question, but I have heard different versions of the meaning to the word "soak" Christine stated 1/2 hour soak? Can you please elborate and describe what you mean by "soak".

Thank you DEE



#8 Christine

Christine

    Advanced Member

  • Members
  • PipPipPip
  • 106 posts
  • LocationUK

Posted 21 June 2010 - 05:15 PM

Please forgive this question, but I have heard different versions of the meaning to the word "soak" Christine stated 1/2 hour soak? Can you please elborate and describe what you mean by "soak".

Thank you DEE




Hello Dee - by "half-hour soak" I mean getting the kiln up to your chosen firing temperature and then keeping the kiln at that temperature for half an hour before letting it gradually cool as usual. It is important that the temperature is maintained only and not increased

Hope this is useful
Christine

#9 Dee Sota

Dee Sota

    Newbie

  • Members
  • Pip
  • 9 posts

Posted 23 June 2010 - 02:20 PM


Please forgive this question, but I have heard different versions of the meaning to the word "soak" Christine stated 1/2 hour soak? Can you please elborate and describe what you mean by "soak".

Thank you DEE




Hello Dee - by "half-hour soak" I mean getting the kiln up to your chosen firing temperature and then keeping the kiln at that temperature for half an hour before letting it gradually cool as usual. It is important that the temperature is maintained only and not increased

Hope this is useful
Christine



#10 Dee Sota

Dee Sota

    Newbie

  • Members
  • Pip
  • 9 posts

Posted 23 June 2010 - 02:28 PM

Thank you Christine, that information gives me a better understanding. My kiln has a kiln sitter, with jr cones, soaking may not work in this situation. What if I bump the cone up one instead of Cone 5. do Cone 6.... or cone 6 to cone 7, however I read you don't want to be hotter, but holding... I wonder if it pays to get the digital attachment on a older Skutt kiln? Or start saving for a digital kiln.

Will I ever learn all this? Thank heavens for folks like yourself helping folks like me. Thank you for sharing your knowledge.

DEE

#11 sandy miller

sandy miller

    Newbie

  • Members
  • Pip
  • 5 posts
  • LocationPaine Falls, Ohio

Posted 23 June 2010 - 05:53 PM

Hi Dee,
Look at the pinholes through a hand held magnifying glass. If pinhole looks like an explosion it's coming from the clay body. If it is just a hole with with no visible clay it's the glaze and a soak at top temp for 10 -15 minutes should help.
good luck.

#12 CarlCravens

CarlCravens

    Long-time Dabbler

  • Members
  • PipPipPip
  • 119 posts
  • LocationWichita, KS

Posted 23 June 2010 - 06:32 PM

My kiln has a kiln sitter, with jr cones, soaking may not work in this situation. What if I bump the cone up one instead of Cone 5. do Cone 6.... or cone 6 to cone 7, however I read you don't want to be hotter, but holding... I wonder if it pays to get the digital attachment on a older Skutt kiln? Or start saving for a digital kiln.


You can get digital controllers for nearly any electric kiln. But you can also soak your Kiln-sitter controlled kiln with a bit of patience and attention. I've heard of basically two ways of going about this. (I'm pretty sure I read about this in Zakin's, Electric Kiln Ceramics.)

The first is to more or less ignore the Kiln-sitter... if you're firing to cone 5, use a cone 6 (or 7) in the sitter only as a safety measure, to insure that you don't accidentally over-fire the kiln. Use a traditional cone pack in the kiln to monitor progress, and when the firing cone (target cone, witness cone, whatever you want to call it) bends, turn the kiln down to medium (or whatever setting you find works for your kiln) for the desired soak time. Watch your guard cone to make sure your temp isn't too high.

The second is to load the target cone in the Kiln-sitter (cone 5 for cone 5 firing), and wait for the Kiln-sitter to trip. When that happens, gently lift the Kiln-sitter lever, push the arming button back in, and gently lower the lever so that it doesn't trip the arming button again. You just bypassed the sitter's cone-based trigger and turned the kiln back on. Continue as above, lowering the temp setting, etc.

There are others with experience at this who can give more detail. I haven't done this yet, but I think I'd prefer the first approach... in neither case do you get to just ignore it and let the sitter trip, because you need to be there when you reach your desired temp in order to turn it down. Obviously, a digital controller is going to be a lot more worry-free, but it also adds a lot of expense.
Carl (Wichita, KS)

#13 faber

faber

    Newbie

  • Members
  • Pip
  • 4 posts

Posted 29 June 2010 - 06:24 AM

You may consider the glaze. I have used those glazes to layer in the past and also had problems with pinholes no matter what I did to correct the problem it continued to happen. The color I was getting was beautiful but it was not worth the time I was spending trying to fix it. Good luck.
Juliet


#14 Laragh

Laragh

    Newbie

  • Members
  • Pip
  • 5 posts
  • LocationRaleigh, NC

Posted 09 July 2010 - 11:14 AM


Hi Everyone, Hope someone has an idea for me.... I recently started using some Spectrum 4/6 glazes on my stoneware. I have been overlapping 2 to 3 colors and I love the finish but I have been getting sporadic pinholes and clusters of tiny pinholes. The stoneware is Standard 306 but it is usually being fired at 04 instead of the c4/10 range printed on the box (long story) Does anyone think that the disparity between the bisque temp and the glaze temp is causing the pinholes? I have glaze fired at c5 and c4 with no change in the pinholes... What about the thickness of the glaze? I'm wondering if the pinholes are due to slight thicknesses in the glaze coverage... I would welcome any thoughts



Hello Plattypus...
I had a pinholing problem some years ago and was advised to give a half-hour soak once the kiln reached temperature - it worked for me. It's also the case that clay which is underfired at bisque may retain moisture which could also explain pinholes forming during a higher temperature glaze firing
Hope this helps
Christine



This is what I did..it does help,..but if you're spraying it has a lot to do with the even-ness (sp?) of your spraying technique. When I first started spraying it was white glaze on bisque on very curved and difficult forms...boy did I learn quick! 30 min soak usually fixed my problems when the glaze was applied correctly :)







0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users