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Which Glaze Road To Go Down?


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#21 MMB

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Posted 11 September 2013 - 10:19 AM

Had no idea there were two. Surprisingly enough theyre 4 minutes apart from each other. Awesome. Thank you.



#22 MichaelP

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Posted 11 September 2013 - 10:28 AM

Clear 2617 (glossy, transparent, good with colorants)

 

F-4 Feldspar              46

G. Borate                   30

EPK                           13

Silica                         11

Total                       100

 

Caramel (transparent and glossy)

 

Kona F-4 feldspar         50

Wollastonite                  20

EPK                               10

Silica                             10

Gerstrate Borate            10

Total                           100

+4 – 5 % Red iron oxide

 

My confusion is the conversion of the needed amounts if the intended en result is not a value of ten, if that is even how it goes lol. I hear 8000 gram batches and the idea of breaking that down makes my head explode. Maybe its not that bad.

These are percentages (by weight of dry ingredients). So if your total batch should be 8000 g (which is your 100%), then 50% of it is 4000 g, 10%- 800 g, etc.

 

In case you want to ask what 11% will be, here how it goes:  8000g divided by 100 (to find out what 1% is), and then multiplied by 11.  The result is 880g.  If it's easier for you, use the same formula to figure out any percentage you want, even 50 (which is simply a half of the total :) ).

 

P.S. Note that such things as colorants, etc.  that are mentioned below the Total (like iron oxide in your Caramel Glaze formula) do not add to 100%, but rather add extra %% to it. You may calculate it the same way though. Although it's not correct scientifically, this is how it was intended to be calculated for our purposes. Just don't be surprised that, because of it, the total dry mix will weigh 4-5% more than 8000g (since iron oxide in the recipe adds 4-5% on top of 100%).

 

It brings us to your homework assignement for today. :)

1. How heavy is "4% more than 8000 g"?

2. How much is 5.25% of 7328 oz?



#23 bciskepottery

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Posted 11 September 2013 - 11:49 AM

MMB, thank you for the recipe.  i am STILL trying to find a glaze that is clear and glossy but friendly to green underglaze.  this one does not have zinc, maybe it will be the one.  just tested 16 colored slips under my usual glazes.  all ok except green,  again, and again........

 

Here is the clear I used for the underglazed brush painting works . . . no problems with green underglaze. 

 

So Clear (Michael Sherrill) ^6 Oxidation
 
Frit 3124, 32.2%
NC-4/Minspar, 25.8%
Silica, 19.4%
Whiting, 12.9%
EPK, 9.6%
Total, 99.9%


#24 TJR

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Posted 11 September 2013 - 01:59 PM

Ive been dealing with this idea for the past two weeks. Atlanta Clay is my closest supplier (hour thirty minute drive). I know the more you buy the cheaper and over all cheaper vs the commercial glazes. I feel better after reading up on this thread. I stumbled across a potters site that listed these two glazes...

 

Clear 2617 (glossy, transparent, good with colorants)

 

F-4 Feldspar              46

G. Borate                   30

EPK                           13

Silica                         11

Total                       100

 

Caramel (transparent and glossy)

 

Kona F-4 feldspar         50

Wollastonite                  20

EPK                               10

Silica                             10

Gerstrate Borate            10

Total                           100

+4 – 5 % Red iron oxide

 

Mainly because I already purchased ten pounds of EPK, for other reasons, but I already have a stock of one material might as well find another way to use it. And because I liked what I read about the use of Wollastonite. My confusion is the conversion of the needed amounts if the intended en result is not a value of ten, if that is even how it goes lol. I hear 8000 gram batches and the idea of breaking that down makes my head explode. Maybe its not that bad.

MMB;

I explained this in another post. It is not difficult once you get your head around it.

1.Glaze recipes should total 100. That means 100 grams.

2.Your second glaze has 4 to 5% Red iron oxide. In a 100 gram batch,thay would be 4-5 grams.

3.100 grams of glaze is one paper cup of glaze. This is enough for a few test tiles.

4.To get anicecream pail [plastic] amount of glaze, you multiply each material in the glaze by 10.Your total material will be 1,000 grams.

5. To add the iron to the second glaze, you also multiply 4 or 5 by 10. You get 40 or 50 grams, which you add to the total of the second glaze.

6. If you wanted 8,000 grams, of glaze, or the equivalentof 5 gallons of glaze, you would multiply all of your materials in your 1,000 gram batch by 8.[1,000x 8 equals 8,000.Don't forget the iron, which also gets multiplied by 8. 40 grams x 8 equals 320 grams of iron which is added to the base glaze.

Questions?

TJR.



#25 Min

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Posted 11 September 2013 - 01:59 PM

 

MMB, thank you for the recipe.  i am STILL trying to find a glaze that is clear and glossy but friendly to green underglaze.  this one does not have zinc, maybe it will be the one.  just tested 16 colored slips under my usual glazes.  all ok except green,  again, and again........

 

Here is the clear I used for the underglazed brush painting works . . . no problems with green underglaze. 

 

So Clear (Michael Sherrill) ^6 Oxidation
 
Frit 3124, 32.2%
NC-4/Minspar, 25.8%
Silica, 19.4%
Whiting, 12.9%
EPK, 9.6%
Total, 99.9%

 

 

Here's another ^6 clear, I have used it both with green stain and over green underglaze (Spectrum and Speedball). COE is 6.49 

 

G1216M

Silica  23.8

Kaolin 24.8

Wollastonite 15.2

Minspar 8.6

3134 23.2

Talc 4.3

total 99.9



#26 oldlady

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Posted 11 September 2013 - 08:55 PM

thank you bruce, these both go into my glaze book and i will make them up to cover some things you can see at bluemont.  your pots are so lovely that i am happy to have a glaze you use.


"putting you down does not raise me up."

#27 yedrow

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Posted 11 September 2013 - 09:58 PM

I don't think you can buy Kona f-4 anymore. I believe Minspar is now its replacement, but I'm not sure how exact that replacement is.

 

Joel.



#28 oldlady

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Posted 12 September 2013 - 08:02 AM

thanks, yedrow, i did not know the name minspar.  fortunately i have an 18 gallon rubbermaid tub of Kona F-4 and it is half full.  gotta go spray glazes now, it is going to rain this afternoon.


"putting you down does not raise me up."

#29 MMB

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Posted 15 September 2013 - 11:57 AM

Some very nice responses in here. I have yet to make my venture to the store, but I will within the next week or so. I actually came across a change in an underglaze with this past firing oldlady.

 

I glazed the inside of my cup with Amacos Black Underglaze then used Coyotes Cone6 clear over top. I wasnt sure if the underglaze would be good at cone 6 but I figured Id give it a go. Now Im not mad it didnt stay black but I was pleased with what it did do. Pretty blues. Yes I know its a poorly thrown bottom :blink:

 

img_1006.jpg?w=570&h=427



#30 Mark C.

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Posted 15 September 2013 - 12:18 PM

This is true-

 

(I don't think you can buy Kona f-4 anymore. I believe Minspar is now its replacement, but I'm not sure how exact that replacement is.)

I used traded 18# of F-4 for old c-30 talc which makes my satin matt matt

I still own 2 full 50# bags of Kona F-4

This is another reason to buy bulk materials.

Mark


Mark Cortright
www.liscomhillpottery.com

#31 oldlady

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Posted 15 September 2013 - 10:30 PM

thanks min, i will make this one up, too.

 

 

mmb, lovely color, reminds me of van gogh starry starry night.  it is probably because one of the ingredients in making black is cobalt.  i have seen recipes for black that call for red iron and manganese as well as the cobalt.  have experienced commercial black turning blue several times, cobalt is REALLY strong.

 

if you have never accumulated glaze materials it is a little scary to start.  if you read lots of recipes for the temp you plan to fire to you will notice the ones that make up the bulk of the glazes you may use.   you could put a list of those you see in the first recipe on paper and then add new ones and a checkmark next to the ones that are duplicates.

 

you will soon find that many glazes have to have silica, ball clay, frits of various kinds etc.  price out the ones that come up often in large amounts and see that are really inexpensive in 50 lb bags as opposed to just enough to make a few thousand grams.  buying in bulk is the best way as long as you have the space to store large amounts.  good luck whatever you decide.


"putting you down does not raise me up."

#32 oldlady

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Posted 27 September 2013 - 09:49 AM

test results on these three glazes.

 

overall sherrill was best.  the others, clear 2617 and G1216M each left milkyness on some of the tests.  

 

the green Velvet # 353 underglaze under sherrill was a very dark military green, though the underglaze itself is a nice green.

 

all the other slips i had mixed looked awful under all of the glazes.


"putting you down does not raise me up."




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