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What should I add to this glaze?


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#1 clay lover

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Posted 08 April 2012 - 08:20 AM

A nice satin clear, colorants go well with it. I've used it before at our co- op, but not mixed it for my studio.


Gerstly borate 2.98
Manganese diox 1.5
whiting 22.7
neph sye 23.00
EPK 20.6
silica 20.3
frit 3124 9.0


I mixed and sieved to 60 mesh, but there is an 1 1/2" of very watery liquid that stays on top of the otherwise soft, fluffy 10,000 gram bucket of glaze slurry. Over night it has not settled to the bottom of the bucket, just some more watter on top. This appears the minute I stop stiring.
Is %20 EPK enough clay for this glaze?
I have epsome salts and bentonite. What should I use, since the majority of the bucket is good, no settling, . Whan I try to dip the bisque piece come out through the watery top layer and the glaze sort of washes off.

#2 Mark C.

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Posted 08 April 2012 - 04:12 PM

A nice satin clear, colorants go well with it. I've used it before at our co- op, but not mixed it for my studio.


Gerstly borate 2.98
Manganese diox 1.5
whiting 22.7
neph sye 23.00
EPK 20.6
silica 20.3
frit 3124 9.0


I mixed and sieved to 60 mesh, but there is an 1 1/2" of very watery liquid that stays on top of the otherwise soft, fluffy 10,000 gram bucket of glaze slurry. Over night it has not settled to the bottom of the bucket, just some more watter on top. This appears the minute I stop stiring.
Is %20 EPK enough clay for this glaze?
I have epsome salts and bentonite. What should I use, since the majority of the bucket is good, no settling, . Whan I try to dip the bisque piece come out through the watery top layer and the glaze sort of washes off.


I cannot answer your this watery liquid on top unless maybe the glaze is to thin and you need to have some water poured off?I use a hygrometer to tell.Fluffy is not a term I know with glazes. Thick or thin is more what I know. I power mix the glaze so its all one before testing.If your glaze is washing off then again my guess to much water. Or you have not stired it up first before using.
I also wonder about why the manganese diox. is in a clear glaze but if its working great.
What cone is this glaze my guess is cone 6 as its got so much frit in it?
Does you co-op use a thickener like epsom or bentonite?
Fritted glazes like to settle so thickiners may help that but if the batch is to thin to begin with you need to get this right 1st.
Mark
Mark Cortright
www.liscomhillpottery.com

#3 Marcia Selsor

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Posted 08 April 2012 - 05:21 PM

I agree with Mark on too much water BUT manganese Dioxide should not be in the glaze. If it was suppose to be Magnesium Carbonate, then that would add a lot of powder to the mix because it is a very light and fluffy chemical..not dense at all.
That is my guess. I have seen that get mixed up a number of times...MG is Magnesium and MN is Manganese. Huge difference in the chemicals.
Marcia

#4 TJR

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Posted 08 April 2012 - 09:17 PM

You have some high powered answers there with Marcia and Mark. The manganese dioxide is a dark metallic colourant and would come as a percentage at the end of the glaze. Also, it would not be needed in a clear glaze. Check your recipe again. I also think that you are confusing it with manganese dioxide which is a flux in the glaze. I also concur that your glaze is probably too thin. Try removing the surface water-as much as you can, and remixing it.
TJR.

#5 clay lover

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Posted 09 April 2012 - 07:30 AM

Update;

The base I listed was not the colored version that I used, so, sorry for confusion, I don'y write out glazes very often athough I do mix them at the co-op regularly.

The recepie should have said, for satin blue; Manganese Dioxide is listed in the main ingredients list, with cobalt and copper added as colorants .
This is an adaptation of the satin clear we started with and have used for several years, just my first time to mix this one.

Today when I opened the studio, I checked the slurry. It had thickened up alot during the night and the standing water mixed in well and after 2 hours has not come back to the surface, but to be useable, it needed almost a quart of water added. I checked it before adding water by dipping a bisqued piece for the usual amount of time , adjusting with water and dipping another dry bisqued piece untill the dried thickness on the bisque test piece was correct.

Why do some glazes at 10,000 grams make a much larger ammount of slurry that another with the same dry weight?
Is there a way to know this before mixing? Certain ingredients that take more water?

#6 bciskepottery

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Posted 09 April 2012 - 06:38 PM

We measure (usually) by weight, not volume. Glaze raw materials do not all weigh the same; some are more dense than others. A cup of frit weighs more than a cup of gerstley, for example. As a result, different weights may yield different volumes.

#7 Marcia Selsor

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Posted 09 April 2012 - 09:01 PM

Update;

The base I listed was not the colored version that I used, so, sorry for confusion, I don'y write out glazes very often athough I do mix them at the co-op regularly.

The recepie should have said, for satin blue; Manganese Dioxide is listed in the main ingredients list, with cobalt and copper added as colorants .
This is an adaptation of the satin clear we started with and have used for several years, just my first time to mix this one.

Today when I opened the studio, I checked the slurry. It had thickened up alot during the night and the standing water mixed in well and after 2 hours has not come back to the surface, but to be useable, it needed almost a quart of water added. I checked it before adding water by dipping a bisqued piece for the usual amount of time , adjusting with water and dipping another dry bisqued piece untill the dried thickness on the bisque test piece was correct.

Why do some glazes at 10,000 grams make a much larger ammount of slurry that another with the same dry weight?
Is there a way to know this before mixing? Certain ingredients that take more water?


Frits don't absorb water because they are fired materials. gerstley borate, on the other hand absorbs water and should soak overnight after mixing. Bentonite absorbs a lot of water.
It always..just depends....
Marcia






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