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Nicky S

Hardening of glaze

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37 minutes ago, neilestrick said:

From Digitalfire: Gerstley Borate is also very plastic and thus suspends and hardens glazes as they dry. In fact, few clays have the plasticity and the ability to retain water that GB has. A GB slurry can take many hours to dewater on a plaster batt, even in a very think layer. Thus it is common to find Gerstley Borate based recipes having no clay content. 

I'm not suggesting that Gerstley should be added to anything as a suspender, because it would obviously have other effects on the glaze, but at 35% it will definitely have suspension qualities, and therefore the 5% EPK in the glaze probably isn't an issue.

My last attempt at this and just my opinion. Add bentonite (up to 2%) for recipes without sufficient clay to keep your glaze suspended. Limit your boron to about .5 no more even for cone 04 stuff. And finally she has a high percentage of Gerstley already so I am not sure where we are going with this. I mentioned bentonite because some of the previous posts speculated the recipe was not suspended. Mentioning Gerstley as a suspender in my view is not all that productive.

just my opinion though so it’s worth the cost charged.

Edited by Bill Kielb

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It is used for sculpture 04. 

It is a nice matt that just works for me. I am of course willing to improve it.

 A lot here to take in so I will make notes and report back. Will experiment with the Bentonite. 

I also add these for variations:

Zircopax       10

Tin                          10

Titanium                 10

Black Velvet stain  15

Copper ox 5

Cobalt ox 5

  You can see here in this head below, I layer the glazes, and use wax to inlay .It's an effect I like. 

Thank you all for your expertise , G

 

P1120958.jpg

metropolis-1.jpg

Edited by Grace london

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Nice work! I’ll see if I can conjure up a very dry flat lithium matte tomorrow in the studio. One With better theoretical chemistry. No guarantees but it would be something you could then experiment with and hopefully be easier to maintain. The only different additional ingredient I can think of that I might use is a small amount of wollastonite.

again,, very striking work!

give me a couple days to mix and fire so at least I can send the recipe and some close up pictures

don't worry about the addition to 95, I see many recipes that add up to less or more as folks have done the math by hand over the years.

Edited by Bill Kielb

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32 minutes ago, Bill Kielb said:

Nice work! I’ll see if I can conjure up a very dry flat lithium matte tomorrow in the studio. One With better theoretical chemistry. No guarantees but it would be something you could then experiment with and hopefully be easier to maintain. The only different additional ingredient I can think of that I might use is a small amount of wollastonite.

again,, very striking work!

give me a couple days to mix and fire so at least I can send the recipe and some close up pictures

don't worry about the addition to 95, I see many recipes that add up to less or more as folks have done the math by hand over the years.

Wow, thanks very much Bill. 

Edited by Grace london

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4 hours ago, Grace london said:

It is a nice matt that just works for me. I am of course willing to improve it.

 A lot here to take in so I will make notes and report back. Will experiment with the Bentonite. 

 

You only need the bentonite if you're having suspension problems. It won't help with crystallization. If the glaze works for you, then go with it. You don't really need to change anything if you're not using it on functional pieces. Reformulating may help with crystals, though.

Love those heads!

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23 hours ago, Grace london said:

Wow, thanks very much Bill. 

Just a quick update, I picked two recipes to do a silica progression on. One is durable and reduces your lithium while adding magnesium by way of Talc to see if you like a durable composition (R2O of between 0.2 and 0. 3). The second is basically artistic and attempts to mirror your lithium apportionment To maintain the color influence  that you are familiar with.

both recipes simply seek to move this from a very undefined underfired recipe to a true matte chemistry. The silica progression we do here should help dial in a level of matte.

Expect  to mix today along with some other tests and fire within a couple days.

no guarantees and first recipes usually point towards adjustment for the next round of tests.

just thought I would update you on the progress.CC9BB056-C0E6-4141-93A6-F2086475F7EB.jpeg.6d3bd856b01c0981dd86750391cdc5a9.jpeg6A9CC85A-6FAB-4511-98F8-D2933F191938.jpeg.60bea945db457b4b9ab3d24a32be283b.jpeg

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@Bill Kielb, it's good of you to work on this for Grace. Just an idea but you might want to supply the lithia from spodumene rather than lithium carb to reduce the crystal formation problem she was having as spodumene isn't nearly as soluble as lithium carb. Chemistry is very close to your 2 recipes above.

Your recipe 1 could then be: GB 42.4   Nep Sy 9.9  Spodumene  47.7 total 100  

Your recipe 2 could then be: GB 40.9  Talc 8.4  Silica 1.2  Epk 25.2  Spodumene 24.3 total 100   (The LOI is lower on this than your version of it but it's still very high, I would be concerned with offgassing.)

Also, I feel we have gone off track from the original post and the title of this thread, I'm going to start a new one in the Chemistry section titles Jackeeze Matt Alterations.

 

 

 

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Yes, spodumene better but I committed to trying to stick mostly with the chems she has in stock. We will make a spodumene version at some point I suspect, it will take a bit of thought, or maybe not - you did it! The LOI at this point is an efficiency thing and may or may not be an off gas concern. Epk, Gerstley, silica, and talc, pretty simple. Not a whole bunch to this but we will see if she likes a recipe that is a true matte or if the underfired thing is the winner.

Three  goals at this point, get some clay in this, get this on the map and keep the sodium low while using her stock chems.

oh almost forgot, want to leave her some matte adjustability by way of sliding silica up and down. 

Edited by Bill Kielb

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