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Simon Heath

Dunting Question

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Hi there,

 

New to the forum and wondering if I can draw on some collective expertise.  I have been trying to get a glaze from John Britt's book Complete Guide to Mid-Range Glazes work and having the worst time.  It's a specialty glaze called Binger, with the following composition:

Silica 44.4

Whiting 4

EPK 22.6

Lithium Carbonate 8.8

Zinc Oxide 20.2

 

and Titanium Dioxide 8

Copper Carbonate 2.4

Bentonite 2

 

It produces a stunning lichen-like effect, but everything I have put it on has completely cracked.  I was told this was because of the high Lithium Carbonate content.  The one thing I put it on that didn't have a dunting problem had a shivering problem.  I then tried putting both a clear glossy glaze and a plain glossy glaze from Mastering Cone 6 glazes as an undercoat and then put the Binger on top.  This prevented dunting, but turned into a runny, Grateful Dead-like psychedelic glaze.  Cool, but nothing like the Binger effect I was hoping for.

 

I'm wondering if anyone has experience with this glaze or any suggestions for what I might try?  I'm not ready to give up, as the glaze is stunning (and I just bought a bunch of Lithium Carbonate, which is really expensive!)  Any suggestions or advice is greatly appreciated!

 

Simon

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I haven't. but what clays are you using?

I think the clays are the problem as they obviously are not working with this glaze. 

Also for putting another glaze underneath a glaze only creates a third new glaze.

You need to determine the COE of the glazes and of the clay and get them more compatible.

Shivering can be eliminated but adding a bit feldspar to the clay body to help it fuse. Check John's book and see what clays he used with that glaze.  

 

Marcia

Min and glazenerd like this

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Questions:

 

1. Coe of the glaze.

2. Coe of the clay.

3. Firing schedule.

 

Lithium is not the only issue, there is also over 20% zinc. Zinc is a flux at cone 6 and up.

Pics would be nice. I think crazing might be the better term.

 

Welcome to the forum.

 

Nerd

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Simon, if you have a facebook account, there is a fb page devoted to mid range firing, specifically John Britt's book.  It's called Exploring Mid Range glazes using John Britt's book.  Lots of people have posted their Binger pictures on there.  It's a closed group, but simply ask to be added.  Perhaps someone can help you.

 

Roberta

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Thank you so much for the responses!  I'm not sure of the answers to the questions posed and it is entirely possible that I am out of my league with this glaze (actually referred to as a Cover for Combinations in the specialty glaze section of John Britt's book).  However, I have a wonderful expert at my pottery supply store looking into it for me.  I may be one of the few people on the planet not on facebook, but perhaps I can persuade my wonderful partner to join the group for me.  Here's hoping!

S.

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That's a lot of lithium. Over 5 and you get into iffy territory, can get crazing and shivering on the same piece. If the glaze is overtop of another glaze it's going to in effect dilute the lithium so lessens that somewhat, dependant on the glaze interaction. Agree with Marcia about needing to fit the clay to the glaze, is the dunting on a low expansion porcelain or stoneware?

(I'm another one on the planet that doesn't use facebook)

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I've tried it once, (but later I accidentally broke the piece and  binned it), mine came out alright in most respects but it was just a dull beige, fairly matt in comparison to the pic below and no crystal growth at all. 


 

https://glazy.org/recipes/4602

 

 

It may need a slow cool down programmed in after reaching ^6. 

 

I'll give it another go some time, but my output is not prodigious so it will be a while.

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It's so great that you all take the time to answer questions!  It's on stoneware, haven't tried it on my porcelain yet.  I get crazy beautiful crystal growth, looks like wetlands photographed from an airplane.  The glaze guru at my pottery supply store suggested I slow down both on the way up and down between 950-1150, as quartz inversion takes place at 1050.  I'm going to believe him on this, but it will require me finally entering the 21st century and getting a programmable kiln controller.  Apparently switching it to medium after an hour and a half and then to high after another hour and a half doesn't qualify as a firing schedule.

S.

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