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Anyone read the Glaze Crazing article in julys PMI?


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#1 Pugaboo

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Posted 19 June 2013 - 10:26 PM

I am hoping someone with more knowledge than I, heck even a little more knowledgable than I can help answer a few questions this article brought up. First of all I hope you've read the article in The July August edition of Pottery Making Illustrated.

The glaze they use in the article is Water Blue. I LOVE this color and would like to use it in the future. Are they saying the original crazed recipe is completely unusable or just not usable for food items? In the Water Blue Revision 1 they correct it so it no longer crazes with the addition of Zircopax (and some other stuff) which they say will make it less transparent... How much less? Will it kill the delicacy of the blue in the original recipe? Would the 2 recipe versions still be the same color or will there be a color shift strong enough to make them no longer match?

Here's what I was thinking to do once I get brave enough to try out mixing my own glazes. I would like to use the original crazed recipe to do a loose wave/swirl design around the outside bottom portion of a bowl, mug, canister, vase, maybe even on a plates very outer rim. I would then use the revised recipe to glaze the remaking outside plus the interiors and all food touching surfaces... Would that be safe? Would the colors be the same with just a difference in the surface appearance of cracks and no cracks?

I'm hoping all of you with more experience can explain if and or why this is or is not possible to do.

Terry
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#2 Marcia Selsor

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Posted 20 June 2013 - 06:54 AM

As always you need to test on your clay.

Marcia

#3 Chris Campbell

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Posted 20 June 2013 - 09:23 AM

Marcia is right ... There is absolutely no way to predict what each recipe will do on your clay body other than testing.
Yep, you are going to have to hit the test tiles!!
Why? First of all your ingredients might not be from the same supplier and so that will be a variable. Your measuring will not be the same as someone else. Your water will be different. Your application rate will need to be tested ... thin, thick, medium? Your kiln fires in its own way. Your shapes will affect the flow.
Ask any experienced potter what happens when you change one of these things! It cascades.
So that is why we get a love/ hate relationship with some glazes and why some tend to pare their glazes down to a couple reliable tested ones.
I encourage you to do the tests and find out for yourself especially since you love the glaze color.

Chris Campbell
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www.ccpottery.com

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#4 Pugaboo

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Posted 20 June 2013 - 04:12 PM

Thank you both. I will add the recipe to my glaze notebook and make a note I found it the magazine and when I am ready and feeling brave I will give it a try. Thanks so much it's actually the first glaze article I've read in the magazine that I kind of understood what they were going for (kinda sorta but I recognized the words!) but still not confident to mix up a batch or my own yet. Glazing and I are barely on speaking terms as it is maybe as our relationship becomes more stable and less traumatic I'll be ready to try a glaze from scratch.

Terry
The world is but a canvas to the imagination - Henry David Thoreau

#5 PeterH

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Posted 20 June 2013 - 08:20 PM

Thank you both. I will add the recipe to my glaze notebook and make a note I found it the magazine and when I am ready and feeling brave I will give it a try. Thanks so much it's actually the first glaze article I've read in the magazine that I kind of understood what they were going for (kinda sorta but I recognized the words!) but still not confident to mix up a batch or my own yet. Glazing and I are barely on speaking terms as it is maybe as our relationship becomes more stable and less traumatic I'll be ready to try a glaze from scratch.

Terry


Terry,

Something between an observation and a plea for information from other readers.

When I've fired crackle glazes the crackle can be very difficult to see unless you stain it. Indeed I was convinced that one test firing had not crackled until I rubbed indian ink over the piece.

So the question is, how do you combine visible crackle with functional ware (which will get washed and even dish-washed). [I've seen suggestions about rubbing in oxides and re-firing, but
never seen sufficient details to want to try this. What oxides, how finely divided, etc.]

Regards, Peter

PS I expect that adding zircopax will change the nature of the colour, so that it will not colour-match the original glaze. However I assume that the colours will tend to "complement" each other rather than clash.

#6 Pres

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Posted 21 June 2013 - 08:13 AM

I am hoping someone with more knowledge than I, heck even a little more knowledgable than I can help answer a few questions this article brought up. First of all I hope you've read the article in The July August edition of Pottery Making Illustrated.

The glaze they use in the article is Water Blue. I LOVE this color and would like to use it in the future. Are they saying the original crazed recipe is completely unusable or just not usable for food items? In the Water Blue Revision 1 they correct it so it no longer crazes with the addition of Zircopax (and some other stuff) which they say will make it less transparent... How much less? Will it kill the delicacy of the blue in the original recipe? Would the 2 recipe versions still be the same color or will there be a color shift strong enough to make them no longer match?

Here's what I was thinking to do once I get brave enough to try out mixing my own glazes. I would like to use the original crazed recipe to do a loose wave/swirl design around the outside bottom portion of a bowl, mug, canister, vase, maybe even on a plates very outer rim. I would then use the revised recipe to glaze the remaking outside plus the interiors and all food touching surfaces... Would that be safe? Would the colors be the same with just a difference in the surface appearance of cracks and no cracks?

I'm hoping all of you with more experience can explain if and or why this is or is not possible to do.

Terry


Crazing, as you read in the article is the result of glaze fit. The clay expands and contracts, the glaze expands and contracts. The difference between these movements will sometimes cause crazing. So you need to test this glaze on your clay test tiles in order to see how it works. Then use the same steps as in the article to adjust the glaze to your clay. . . that is if... it crazes. It is an excellent article, and has very good pointers for glaze adjustment. There are several books that have much the same information in various formats that would be helpful. One that comes to mind is Mastering Cone 6 Glazes.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/





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