Jump to content


Photo

Colouring transparent glaze


  • Please log in to reply
5 replies to this topic

#1 High Bridge Pottery

High Bridge Pottery

    Advanced Member

  • Members
  • PipPipPip
  • 443 posts
  • LocationNewcastle Upon Tyne. England

Posted 07 April 2013 - 08:14 AM

Before starting off making my own glazes up (as I am short of money and time) I just bought a premixed transparent glaze, with three underglaze/stains. I started with a bit of experimentation mixing different colourants with the transparent glaze.

I had success colouring the transparent glaze with the (also bought) underglaze/stain but I tried also using iron oxide. The wet glaze had a nice red tint but when it came out the kiln this morning the iron oxide only seemed to have succeeded in making the thicker parts of the glaze stay transparent and not turn white. The normal transparent glaze where thickest turned white.

Any explanation? Also any tips on inventive ways to colour my transparent glaze, I have a few different oxides.

Fired to 1240 centigrade after applying to bisque. Stoneware clay

#2 JBaymore

JBaymore

    Moderator

  • Moderators
  • 2,956 posts
  • LocationWilton, NH USA

Posted 07 April 2013 - 09:21 AM

Red iron oxide is a powerful "stainer" of the wet base glaze batches. It aways looks like more than it really there.

For coloration, it can take quite a bit (percentage of total dry batch weight) of iron oxide to haver a significant coloring effect. So example some tenmoku blacks and saturated iron reds take between 10 and 12% of the total DRY weight of material to get those dark colors. For celadons (on white clay) as little as 1/2% will give a subtle ice blue or light green....... but on stoneware would show little difference from the clear glaze.

Are you firing oxidation or reduction?

best,

.......................john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#3 High Bridge Pottery

High Bridge Pottery

    Advanced Member

  • Members
  • PipPipPip
  • 443 posts
  • LocationNewcastle Upon Tyne. England

Posted 07 April 2013 - 10:45 AM

Just oxidation in an electric kiln, that's all I have to use at this moment in time.

More iron oxide is probably the key, I added the same amounts of oxide as I did the purchased underglaze/stain. The stain coloured the glaze very well. Shame about my technique at applying the glazes Posted Image
I seem to have much better results just painting it on instead of dipping or pouring. Always to thick and lots of drips with the latter.

#4 Benzine

Benzine

    Socratic Potter

  • Members
  • PipPipPip
  • 1,590 posts
  • LocationThe Hawkeye State

Posted 07 April 2013 - 11:21 AM

As an experiment, before trying it on a student project, I used a black iron oxide stain, and then put an Amaco clear transparent over the top. The project was a sculpture, and the student wanted an antique sculpture look, but also a gloss to it. So, as a precaution I tried layering the two, on a scrap piece of bisqueware I had sitting around. I'm glad I did, because putting the clear on top, caused the black stain to turn dark green.
"Anything worth believing, is worth questioning"

#5 Roberta12

Roberta12

    Advanced Member

  • Members
  • PipPipPip
  • 134 posts
  • LocationColorado

Posted 09 April 2013 - 04:30 PM

Just oxidation in an electric kiln, that's all I have to use at this moment in time.

More iron oxide is probably the key, I added the same amounts of oxide as I did the purchased underglaze/stain. The stain coloured the glaze very well. Shame about my technique at applying the glazes Posted Image
I seem to have much better results just painting it on instead of dipping or pouring. Always to thick and lots of drips with the latter.



I am coming to England the end of May. We will travel from London to Scotland by train. Where are you from London?

Roberta

#6 High Bridge Pottery

High Bridge Pottery

    Advanced Member

  • Members
  • PipPipPip
  • 443 posts
  • LocationNewcastle Upon Tyne. England

Posted 10 April 2013 - 10:30 AM

Newcastle upon Tyne, far north of London but if you are traveling to Scotland you will be coming right past Posted Image Here is a map that I found very quickly map

Just google Newcastle upon Tyne and you will find a better map, but I couldn't work out how to link them into this post.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users