Identify a glaze

[Julia8989]

https://www.google.com/maps/uv?pb=!1s0x484f9284fed2bc59%3A0xb58a060d44581e22!5sJulia Clarke Pottery!15sCgIgARICEAE&authuser=1&imagekey=!1e10!2sAF1QipPLh7uG7iTEJXb2wQy8DygY8GyEpQzoXLojRGFm#Hi

Hi  Everyone, Im trying to identify the glaze of this pot or something similar. It gives a melted glass look in the bottom.

Apologies I dont know what the URL is  I had to post to my Google business in order to get a link, its just a personal photo and I have no idea if Ive done it correctly ,

its just a load of jargon to me !

Thanks in advance, Julia

 

 

[JohnnyK]

Welcome to the Forum, Julia! I would guess that it is a thick layer of clear glaze since the crazing of the green shows through...

[Callie Beller Diesel]

We couldn’t do something like give you an exact recipe just by looking at this image, or even ballpark it without knowing what temperature it was fired to. The best we can do give a set of parameters to look for in order to replicate the effect. It’ll get you in the ballpark, but you’ll still have to do some testing. 

There’s some flaws here that would make me think whatever this exact glaze is, it’s probably not the best glaze to use as a liner. The glaze pooling that deeply and the heavy crazing could indicate that this glaze runs quite a bit, and that it might not be the most durable thing ever. Usually a glaze that heavily crazed will cause a pot to weep if the clay you’re using isn’t fully mature at the cone you’re firing to. The runniness could mean that the glaze is over fired at this temperature, or that it has too much flux and consequently might not be durable. 

The good news is, there’s lots of ways to get this shade of green in a more user friendly fashion at a variety of working temperatures. If you let us know what temperature you’re firing to and what clay you’re using, we can point you in the right direction.

[Min]

10 hours ago, Callie Beller Diesel said:

Usually a glaze that heavily crazed will cause a pot to weep if the clay you’re using isn’t fully mature at the cone you’re firing to

@Julia8989, just going off on a little tangent here and adding to  thought to Callie's post. Terms such as "mature" can be open to interpretation. Without trying to overwhelm a new potter with verbiage, in order for functional pots not too weep or leak, especially with a crazed glaze such as the one in your image, the clay would ideally need to have an absorption figure of less than approx 1.5%  This means that the clay will absorb less than that amount of water when put through some tests to measure how much water the clay soaks up. Maturity can be a confusing term. With ceramics it generally means the point at which a claybody is as strong and dense as it will get without being over-fired and suffering from warping, bloating, brittleness and some other faults. For example, earthenware when fired to maturity can have an absorption rate well over 10% while porcelains get down to 0% and stonewares in between those two amounts. If you do try a heavily crazed glaze such as in your image its more important than ever to check the absorption of the clay you will be using at the firing cone you will be firing it to. 

Edited April 21, 2023 by Min
Grammar

[Piedmont Pottery]

On 4/20/2023 at 8:45 AM, Julia8989 said:

https://www.google.com/maps/uv?pb=!1s0x484f9284fed2bc59%3A0xb58a060d44581e22!5sJulia Clarke Pottery!15sCgIgARICEAE&authuser=1&imagekey=!1e10!2sAF1QipPLh7uG7iTEJXb2wQy8DygY8GyEpQzoXLojRGFm#Hi

Hi  Everyone, Im trying to identify the glaze of this pot or something similar. It gives a melted glass look in the bottom.

Apologies I dont know what the URL is  I had to post to my Google business in order to get a link, its just a personal photo and I have no idea if Ive done it correctly ,

its just a load of jargon to me !

Thanks in advance, Julia

This looks like crushed up wine bottle glass in the bottom covered with a transparent glaze.  Many years ago, I was experimenting with glass on stoneware, and this looks a lot like some of those results.  The wine bottle glass always crazes due to having a COE much greater than the stoneware.  My goal back then was to cover the glass with a layer of transparent graze that would not craze but still showed the crazing of the bottle glass beneath it.  I never got it to work to the point where none of the crazing propagated though the transparent glaze.

 

 

[PeterH]

15 minutes ago, Piedmont Pottery said:

This looks like crushed up wine bottle glass in the bottom covered with a transparent glaze.

If so this thread may be of interest
 

This thread referenced a paper, but the link provided is dead.
The_Combination_of_Glass_and_Ceramics_as_a_means_of_artistic_expression_in_studio_practice_Jessamy_Kelly

This paper can still be found at several places, including
https://sure.sunderland.ac.uk/id/eprint/3656/1/The_Combination_of_Glass_and_Ceramics_as_a_means_of_artistic.pdf