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Wiping Glaze After Dipping


Judith B

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Hello,

 

I need some help! I work for a potter who uses a very finicky stoneware: when it is bisqued, any contact with water (whether it's my hands that are not perfectely dry, or a sponge) will leave a dark stain after the firing.

I am not sure I understand why but it makes the glazing quite difficult. For a lot of pieces, she only glazes the inside and so sometimes it spills outside when I pour it out, or even the rim needs to be cleaned. But if I wipe it off with a sponge, it will leave that ugly stain.

So I don't know how to clean the glaze in the unwanted places without screwing up everything. I tried to scrape it with a knife and then sand lightly but I'm not sure if it will be enough to take all the glaze off. I'll have the result in a couple of days. But if you have any recommendations, I'd love to hear about it!

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Weird.

 

The first thing I would do is ask the potter why this is happening.

 

A couple possibilities occur to me.  Is the stoneware pale?  If so, maybe the local water has a high iron content, and you could use distilled water to sponge off the g;aze.

 

The other is that the glaze may have soluble ingredients in it, and they soak into the body.  It's barely conceivable that getting the outside wet allows those solubles to migrate through from the inside.

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I'll try to take some photos next time. She uses a stoneware that's beige after firing. Here are a couple pictures of how it looks like :

http://instagram.com/p/vBzEhhKuHi/?modal=true

http://instagram.com/p/vweVwiquHw/?modal=true

 

Maybe it could be the water yeah, that would be a good thing to investigate for sure! In any case, since I am not so good at dipping and always end up with glaze all over the place, (I am working on it, I swear) I wish I knew what was going on. But she also uses some Bmix stoneware and this one doesn't have the same reaction, it happens only with that specific stoneware. So I would tend to say it would be the clay. I don't know. I'll check what kind of clay she uses too

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It looks kinda like the h400 series out of Plainsman. It's a mix high in local clay that does all kinds of fun things with fluorescing. You could call Plainsman to help troubleshoot (they are the guys that run Digitalfire), but if it is in that 400 series, your boss has already given you the best solution: don't get it wet. (400 series is better for sculptural use because it tends to be quite porous, even when mature. It is possible to use it for functional purposes; they just recommend A well-fitted glaze If you go that direction.)

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