Jump to content


Photo

Dipped Glaze Producing Air Bubbles


  • Please log in to reply
4 replies to this topic

#1 yarddog

yarddog

    Member

  • Members
  • PipPip
  • 20 posts

Posted 30 October 2013 - 10:57 PM

A midfire Shino I recently mixed up is misbehaving. Dipped pots are emerging from the glaze covered with air bubbles. I have a leftover bit of the same formula that covers just fine. I mix the glaze very gently, so I'm pretty sure I am not causing it by stirring air into the glaze.
And any other glaze over the Shino will also be pitted with air bubbles, although the second glaze will cover perfectly elsewhere on the same pot...
Worst of all, I'm embarrassed to admit that this same thing happened to me last year, but I'll be damned if I can remember the cause or solution.
Could someone help this dunderhead?

#2 bciskepottery

bciskepottery

    Advanced Member

  • Members
  • PipPipPip
  • 1,240 posts

Posted 31 October 2013 - 06:35 AM

Does your shino have soda ash in it? I want to recall that soda ash, when stirred, can create the air bubbles in the glaze. (Remember, the soda ash migrates to the surface of the pot to form those really cool crystal fuzzy thingies for carbon trapping.) They will go away if you allow some time between stirring and dipping. Or you can use a strainer to skim the surface of the glaze to remove the air bubbles. I think soda ash loses its potency over time, which might explain why your older shino does not have the problem.

#3 Marcia Selsor

Marcia Selsor

    Professor Emerita, Montana State University-Billings

  • Members
  • PipPipPip
  • 3,518 posts
  • Locationwhere Texas, Matamoros, Rio Grande and Gulf of Mexico come together.

Posted 31 October 2013 - 07:19 AM

you can spray the bubbles with diluted alcohol before dipping.The alcohol cuts the surface tension and bubbles vanish instantly.No harm to the glaze.
Marcia

#4 Mart

Mart

    Advanced Member

  • Members
  • PipPipPip
  • 280 posts

Posted 04 November 2013 - 01:58 PM

I mix the glaze very gently, so I'm pretty sure I am not causing it by stirring air into the glaze.

 

Unless the glaze looks like foamy head of a freshly poured pint of bitter... you are fine.
 

Dipped pots are emerging from the glaze covered with air bubbles.

Is your glaze too thick or you put it on too thick?
Use your finger to smooth out those bubble craters on the bisque and you will be fine.

 

Any chance you can upload a small image of that bubbling glaze?



#5 Mart

Mart

    Advanced Member

  • Members
  • PipPipPip
  • 280 posts

Posted 04 November 2013 - 02:25 PM

Could it be outgassing of your clay body causing the bubbling, and not the glaze?

As I understand it, this is before firing.

 

....emerging from the glaze covered with air bubbles.

 






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users