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Clear glaze question!


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I made a few items with Navajo Wheel (no grog) cone 5. They were bisqued then I applied a cone 5 clear glaze. After they were fired they came out a dark grey. I was surprised (and disappointed!) because I thought they would be the red terra cotta color of the clay body. What did I do wrong?? 

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4 minutes ago, olivequeen said:

I made a few items with Navajo Wheel (no grog) cone 5. They were bisqued then I applied a cone 5 clear glaze. After they were fired they came out a dark grey. I was surprised (and disappointed!) because I thought they would be the red terra cotta color of the clay body. What did I do wrong?? 

Is the bottom a dark red clay color?  I don't know of any cone 6 red clays that will appear terra cotta colored, that's more of a bisque temperature color.

What I'm going to guess is that the red clay caused a bunch of micro bubbles in the clear glaze making it appear gray.

 

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From the pic I just looked at from the IMOC website, it looks like it goes fairly brown at cone 6, which is to be expected. With a clear glaze it will be more gray. If you want the red terra cotta color with a glaze over it, you have to work at low fire temps.

FYI, the absorption rate of that clay body is 2.9% at cone 6, so it's not great for functional work. It is likely to absorb and weep moisture.

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@olivequeen, if you are looking for a brick red cone 6 clay Georgies Dundee Red might be worth trying, when I used it a few years ago it was definitely more red than brown.  At cone 6 it's nice and tight so it's good for functional pots. There is a slight tooth to it unlike the Navaho Wheel red clay but they don't include that in the description.  Imco has 2 smooth Navaho Wheel clays, one is the original one that used to fire to cone 6 but now needs to go to cone 8 which they call Navaho Wheel Regular the other is Navaho Wheel Classic which is the cone 5/6 version.  If you make your own glazes try the Alberta Slip recipe here, the iron in the Alberta Slip helps clear the bubbles as does not having a high alumina content in the glaze.

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