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Scm And Wrights Water Blue Peeling


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#1 docweathers

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Posted 08 October 2013 - 03:45 PM

I'm spraying many different glazes on the same cone 6 white stoneware bisque to cone 06.  Everything except SCM and Wrights Water Blue  are sticking well, even when very thick.   I've tried spraying these two with a thin glaze mix and as thick as heavy cream. The result is the same. Even when applied thin, they begin to peel before they are very dry. My studio is about 50° and it's raining outside, so the humidity is high. So they should be drying slowly.

 

What is different about these glazes and what can I do about it?


Larry

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#2 Marcia Selsor

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Posted 08 October 2013 - 05:42 PM

I don't know either one. Maybe you should post the recipes and mention your particular clay body.Are your pots clean?
dust free, grease free?

Marcia

#3 docweathers

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Posted 08 October 2013 - 07:44 PM

I am using G-mix 6 with grog from Georgie's in Portland. My test files are clean, dust free and dry.  What's bewildering is that I have put about 15 other glazes on the same tiles over the last couple of weeks and had no problem, even when they were very thick.

 

Here are my glaze recipes.

 

 

wrights water Blue glaze   (Cone 1–6., oxidation)

 

Lithium Carbonate . . . . . . . . . . . . . . . 3 %

Strontium Carbonate . . . . . . . . . . . . . 9

Ferro Frit 3110 . . . . . . . . . . . . . . . . . . 59

EPK Kaolin . . . . . . . . . . . . . . . . . . . . . 12

Silica . . . . . . . . . . . . . . . . . . . . . . . .    17

                                                          100 %

 

Add: Bentonite . . . . . . . . . . . . . . . . . . . 2 % Copper Carbonate . . . . . . . . . . . . 5 %

 

----------------------

 

Strontium Crystal Magic (SCM)     Cone 6-10

 

Custer Feldspar...........40

Whiting........................15

Strontium Carb............11

6 Tile Kaolin................13

3124 frit........................4

Lithium Carb................ 4

Titanium Dioxide.........12

Bentonite......................2

 

Total                           101


Larry

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#4 bciskepottery

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Posted 08 October 2013 - 09:05 PM

Are only the Steven Hill glazes giving you a problem?  Are they intended for spraying on greenware (I believe SH once fires) or for bisque?



#5 docweathers

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Posted 08 October 2013 - 09:54 PM

The SCM is from Stephen Hill but the Wright's Water Blue  is not. SCM seems to be widely used since I've seen many posts on this forum about it.


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#6 docweathers

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Posted 10 October 2013 - 10:07 PM

Can anyone give me any clues about what's going wrong here?


Larry

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#7 atanzey

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Posted 11 October 2013 - 06:22 AM

Larry - I had the same problem with Wright's Water Blue - on my stuff, the first coat would be okay, but any overlap (even almost immediate runs) would flake off.  Applications over other glazes ended up on the table or in the bottom of the pot.  I tried wetting the ware, working faster, etc.  I finally just quit using it, as it had a serious crackle problem on my clay, any way.  Sorry to not be of any real help, but I'll be watching to see if anyone has any input as to why this happens.  Your glazes both have Strontium and Lithium carb - I wonder if that's a coincidence...

 

Alice



#8 Min

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Posted 11 October 2013 - 10:50 AM

Not sure if it’s much help but when I was trying out SCM I used the glaze at a very thin consistency, I didn’t keep the test bucket or I would measure the SG for you. It was skim milk consistency and I used just a very light spray of it. I mixed it very thin then added a tiny bit of Epsom salts solution to suspend it plus some blue food dye so I could see where I was spraying it. I know Hill says that approx 1/3 of total glaze thickness should be SCM but really how do you judge that fine a nuance?

 

The other thing you could try would be to swap EPK for the Tile 6, the EPK is less plastic and will shrink less. Also, just in case it's something odd with your clay do you have test pieces of another clay you could try it on?  Is crazing going to bother you with the Wrights Water Blue, it has a really high coe at 8.68, I imagine it will craze on GMix + grog.

 

All the best with your testing!



#9 docweathers

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Posted 11 October 2013 - 01:51 PM

I've tried the skim milk glaze and it comes off too. I think the best thing I can do is to focus on my other glazes and leave these two until I have greater wisdom.

 

Thanks for the suggestions.

 

Larry


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#10 Babs

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Posted 14 October 2013 - 07:02 PM

I too am having trouble with Wrights Blue.

On first trying this glaze it seemed friable but nearly OK. Then I had to go with a different clay body, supplier closed down.

On second attempts and thereafter it cracks, like dry clay and falls off the pot, even onto an element!!

Great colour but too risky to go on with, is there a ceramic chemist out there who knows how to prevent this cracking and flaking in glazes prefiring? Gum additive? Compatibility of clay body?? I've tried different thicknesses of application, damp and dry pots, or perhaps a higher bisque for this glaze?

The SCM recipe is not in percentages, the titanium and other colourant should not be included in the maths of attaining a percentage, if that makes sense.

Babs



#11 SmartsyArtsy

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Posted 19 October 2013 - 01:53 PM

I have also had this problem with WWB. I use it very lightly. If dipped, I just really work the cracks with a finger. Mostly I brush it on, but needed to add CMC. I am not looking for a consistent coloration when I do this, so my brush strokes are brief. In fact, I used it I. The tile in my avatar over another blue. I tried a couple of other glazes tha react this way, and I have yet to analyze them.




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