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Problem with Temmuko Gold glaze c6


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#1 Raku nut

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Posted 22 March 2013 - 11:37 AM

Hi all,
I have mixed this glaze before and it was very stable and lovely. Whre it was thin it was a transparent treacle color. This time it is unrecognizable. It feels rough and ran off the pot causing it to crack. I checked with my local ceramics supplier and he pointed out the problems with the formula and advised that I use a glaze software program to check formula's before I use them. But it did work before, so I think it is a mistake that I made in either mis-weighing or missing something. The specific gravity is too low; so I can remove some water and test it again, but it is so different that I don't think that is the only issue. Is there any point to trying to fix this, or am I better to throw it away?

Temmoku Gold c6
Cornwall Stone 61.
Whiting 8.
Borax 3.
Lithium carb. 5.5
Dolomite 7.
Flint 5.5
Red Iron Oxide 10.

:(/>

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Sandy

#2 mregecko

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Posted 22 March 2013 - 01:05 PM

This photo honestly doesn't look too far off for a lot of gold-flecked ^6 temmokus that I have seen.

Where thin, they produce a light purple color. Where thicker, they produce a black-brown with a varying amount of gold flecks (sometimes almost entirely covered in them).

Looking at this platter, I'm guessing that you dipped it into a bucket by holding one handle? The right side looks a good bit thicker than the left.

Two things to consider:

  • Consistency of the glaze (too thin and it will settle quickly, making even coats hard). You already acknowledged the specific gravity was off and you might have to slake off some water. This seems likely to me.
  • I punched it into a couple of online glaze analyzers (http://www.glazesimu...m/recWizard.php is my favorite), but everything looks OK. Color ranges should go from temmoku brown to a purplish, which is what you see in the photo. If it's runny, is it possible that you mis-measured and there's a little too much of the fluxing agents? Or maybe your kiln ran hot?
Hope this helps some! :-\

#3 smastca

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Posted 22 March 2013 - 07:59 PM

My recipe for it uses Gerstley Borate(99) not Borax. Mine is black with gold flecks.

#4 Raku nut

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Posted 23 March 2013 - 01:06 AM

My recipe for it uses Gerstley Borate(99) not Borax. Mine is black with gold flecks.



Yes, I noticed that other formulas used GB not Borax and that could be better. As this was the formula in my book I think this is the same one I have had good results with before; which would be variations between black with some gold flecking and a transparent treacle. I will try removing some water and do a small test. If that doesn't change it there may be too much flux. Would you reccomend adding clay or alumina? I am programming for cone 5, but I know that in places the cone 6 is also down, but nothing else has run.
Thank you, I appreciate your help. There is certainly a lot to learn with your own glazes, but it is definitely worth it.
Thanks,
Sandy
Sandy

#5 ayjay

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Posted 23 March 2013 - 03:02 PM

I've only glazed one piece so far with Tenmoku gold, it looks similar to the RHS of your piece, (although I prefer the look of your glaze)

Attached File  DSCF1518.JPG   434.07KB   33 downloads

Recipe I've got was from the www

Cornish Stone 61
Whiting 8
Gersley Borate 3
Lithium Carb. 5.5
Dolomite 7
Silica 5.5
+ RIO 10

I subbed other stuff for the Cornish Stone as I don't have any.

#6 Raku nut

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Posted 24 March 2013 - 01:25 AM

I've only glazed one piece so far with Tenmoku gold, it looks similar to the RHS of your piece, (although I prefer the look of your glaze)

Attached File  DSCF1518.JPG   434.07KB   33 downloads

Recipe I've got was from the www

Cornish Stone 61
Whiting 8
Gersley Borate 3
Lithium Carb. 5.5
Dolomite 7
Silica 5.5
+ RIO 10

I subbed other stuff for the Cornish Stone as I don't have any.

Hi, That is very similar to the thicker side that ran off on my piece. I wonder if the Gerstley Borate made that much difference. I am attaching a closer view of a previous piece glazed in my last batch. It didn't really show much flecking but was a really nice transparent that was well behaved.

Attached Files


Sandy

#7 smastca

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Posted 24 March 2013 - 12:14 PM

What was the other glaze that you put under it? That could have influenced it as well.

#8 trina

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Posted 24 March 2013 - 02:44 PM

hi there, looks to me like reduction, could that be possible T

#9 Raku nut

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Posted 25 March 2013 - 01:39 AM

What was the other glaze that you put under it? That could have influenced it as well.

I slip trailed some oatmeal on it in the center.
Sandy

#10 Raku nut

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Posted 25 March 2013 - 01:43 AM

hi there, looks to me like reduction, could that be possible T

I'm not sure what could have been present that would have reduced it. I wasn't trying anything, and everything else was normal.
Sandy




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