Shivering

[LaniJones]

My pieces are prone to shivering. I am using Coloborria low fire dipping glaze with gebeo low fire white clay. They have the same firing temp (cone 06) but shivering is still occurring. I think this is due to thermal expansion being different in both but don’t know how to figure this out - can anyone help or suggest a good combination of low fire clay and glaze?

[Callie Beller Diesel]

Hi and welcome to the forum!

My google-fu is coming up with a modelling clay brand when I search for “gedeo.” It comes up Pebeo Gedeo, and I did find a mention from Jackson’s of a clay by that brand that can be fired to low fire temps, but not a proper spec sheet on it. Where did you buy it?

[Hulk]

Hi Lani!

Not finding any info on Coloborria glaze (one match, from a scanned San Paulo newspaper, 1920s).

In my limited experience, crazing is more common than shivering (which doesn't help you...); it does happen, however, and it is more dangerous, for sure. Here's a link:
Shivering (digitalfire.com)

Your question, that's a good one - this glaze fits that clay - golden, if you can get an answer!

I'm mixing glazes from raw materials, and have traveled the reformulating glazes to fit road, with some success. Trying some different clays was worthwhile for me, and asking (the right person, got lucky there) at the clay factory "How does this white stoneware compare to that one in terms of crazing?" was ...golden. Now I'm not entirely sure if I'll ever try any new clays...

P.S. I'm working with cone 5/6 materials, else I'd list some specific "fits"

[PeterH]

If anybody can make anything from it ...

Advert for
GÉDÉO MODELLING CLAY WHITE 5 KG LOAF
https://en.pebeo.com/catalogue/famille/gedeo-modeling-materials/766303

Initially says
We recommend firing in a kiln between 980 and 1050 ºC (1800-1925 ºF) and decorating with enamel.

But later says
When the piece is finished, let it air dry. It is recommended to fire in a ceramic kiln between 980 and 1050ºC (1800-1925 F) and to decorate it with glazes.

----

Advert for
Colorobbia Superclear Low-Fire Dipping Glaze (3 gal)
https://www.potclays.co.uk/colorobbia-superclear-dipping/colourobbia-superclear-low-fire-dipping-glaze-(3-gal)

Which includes

This glaze is ready to use after thorough stirring.

Water addition is necessary only to maintain the original condition of the glaze: Ford cup (viscosity) 19-20”. Once diluted, glaze must be used in a reasonably short time.

This product is suitable for firing in electric kiln. The firing temperature range is from 960°C (1,760°F) to 1,060°C (1,940°F), recommended temperature 1,000°-1,015°C (1,850°F) or Orton 06.

This glaze is suitable for the most common ceramic bodies having a coefficient of thermal expansion of 59-60 x 10-7 and it is China-painting, gold and lustre compatible.

[neilestrick]

Are you sure the glazes are getting stirred/mixed completely during use? Is this fresh clay, not recycled?

Sometimes low fire glazes shiver without a good reason, but I would test them at cone 05 and 04 if it's happening a lot.

Are you using cones? A pyrometer alone isn't a good indicator of heat work.

[LaniJones]

49 minutes ago, neilestrick said:

Are you sure the glazes are getting stirred/mixed completely during use? Is this fresh clay, not recycled?

Sometimes low fire glazes shiver without a good reason, but I would test them at cone 05 and 04 if it's happening a lot.

Are you using cones? A pyrometer alone isn't a good indicator of heat work.

I am using cones yes! I may try at 05 to see what happens! Thanks

[LaniJones]

1 hour ago, PeterH said:

If anybody can make anything from it ...

Advert for
GÉDÉO MODELLING CLAY WHITE 5 KG LOAF
https://en.pebeo.com/catalogue/famille/gedeo-modeling-materials/766303

Initially says
We recommend firing in a kiln between 980 and 1050 ºC (1800-1925 ºF) and decorating with enamel.

But later says
When the piece is finished, let it air dry. It is recommended to fire in a ceramic kiln between 980 and 1050ºC (1800-1925 F) and to decorate it with glazes.

----

Advert for
Colorobbia Superclear Low-Fire Dipping Glaze (3 gal)
https://www.potclays.co.uk/colorobbia-superclear-dipping/colourobbia-superclear-low-fire-dipping-glaze-(3-gal)

Which includes

This glaze is ready to use after thorough stirring.

Water addition is necessary only to maintain the original condition of the glaze: Ford cup (viscosity) 19-20”. Once diluted, glaze must be used in a reasonably short time.

This product is suitable for firing in electric kiln. The firing temperature range is from 960°C (1,760°F) to 1,060°C (1,940°F), recommended temperature 1,000°-1,015°C (1,850°F) or Orton 06.

This glaze is suitable for the most common ceramic bodies having a coefficient of thermal expansion of 59-60 x 10-7 and it is China-painting, gold and lustre compatible.

This is what I’m using!

[LaniJones]

1 hour ago, Callie Beller Diesel said:

Hi and welcome to the forum!

My google-fu is coming up with a modelling clay brand when I search for “gedeo.” It comes up Pebeo Gedeo, and I did find a mention from Jackson’s of a clay by that brand that can be fired to low fire temps, but not a proper spec sheet on it. Where did you buy it?

Amazon! I appreciate it may not be the best place to buy clay..  but it’s low firing and my kiln struggles to reach the higher temps

[Min]

@LaniJones,  I would call up the supplier you purchased your glazes from and ask which claybody they recommend as being suitable (glaze fits without shivering or crazing) for the glaze you have. I’ld also be asking for a lowfire  or earthenware clay, not one of the wide firing range bodies that seem so common in the UK. From past discussions here on the forum there don’t seem to be widely available cone 6 (midrange) bodies, but rather broad range bodies that won’t be mature unless fired to their highest cone specified. As has already been said your glaze doesn’t fit your current clay, one or the other needs to change.
 

1 hour ago, LaniJones said:

but it’s low firing and my kiln struggles to reach the higher temps

Might be time to consider replacing the elements. What temperature is your kiln rated?

[LaniJones]

19 minutes ago, Min said:

@LaniJones,  I would call up the supplier you purchased your glazes from and ask which claybody they recommend as being suitable (glaze fits without shivering or crazing) for the glaze you have. I’ld also be asking for a lowfire  or earthenware clay, not one of the wide firing range bodies that seem so common in the UK. From past discussions here on the forum there don’t seem to be widely available cone 6 (midrange) bodies, but rather broad range bodies that won’t be mature unless fired to their highest cone specified. As has already been said your glaze doesn’t fit your current clay, one or the other needs to change.
 

Might be time to consider replacing the elements. What temperature is your kiln rated?

I will definitely call my glaze supplier tomorrow. Many thanks!