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I've had this happen occasionally, but now it seems to be more frequent.  After dipping a mug in a commercial clear glaze, the surface has an odd pattern, like webbing.  I think this happens only on mugs, but that seems pretty weird.  Usually on the inside, but the outside and handles are also affected sometimes.  I don't know if it's coincidental (there are no...?), but it happens with certain underglaze colors primarily.  

 

Does anyone know WHY this happens?  Is there anything anyone can suggest?  I think it fires pretty well, the pattern melts, but I'm always concerned it won't...

 

Thanks for your help!

Carol

 

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Are these hand built? If so, does that webbing match the texture of the cloth you roll your slabs on?

Yes, they are hand built, but the slabs are moved from canvas to dry-wall and rib-smoothed in all directions.  So, I don't think that's it - thanks though!

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What's under the glaze? It looks a bit like what happens sometimes when I glaze right over a Mayco underglaze without firing the binder out of it first.

Thanks for your reply.  Actually I use some Mayco underglazes, but notice this happening on Amaco's products.  And it happens most often on black and turquoise (Velvets and LUG).  And... these mugs were slowly bisque'd to ^04.  But I think you're on the right track...

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I have seen patterns like this when dipping a previously glazed heated pot.  So I would assume your glaze isn't adhering well to the under glaze.   Denice

Hi Denice,

Okay, to be sure we're on the same page - the mugs have been bisque'd to 04 and this is the first time I'm glazing them.  

 

And YES! I've had problems with glaze not adhering to some areas of the underglaze.  I posted about it last year, actually, and resolved it, mostly, by making sure the glaze is not too thin, especially on edges.  It's weird, though, because both the underglazes and glaze are Amaco products - wouldn't you think they'd work well together?  Do you have any suggestions about what to do?  This pattern occurs mostly on black and turquoise (Velvet & LUG)...

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A misfire perhaps, but I find it to be a very intriquing glaze effect.

Nerd

 

I know - it's actually beautiful!  And it does blend out during the ^6 firing.  But I think there's gotta be a problem hiding here somewhere....  I'm in St. L, too, btw... 

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Carol have you tried another brand of underglaze, there can be a big difference from brand to brand in how they work.  Have you tried spritzing some water on the underglaze before you put the clear on it.    Denice

 

If it's the underglaze, I just had to start doing my decorating on leather hard clay, rather than the bisque. It fixes the problem just fine.

Hey Denise & Diesel Clay -

 

I apply the underglaze to leather hard clay & then sgraffito.  Bisque at ^04, then apply glaze and fire ^5.  If I remember, sigh, I do rinse the bisque ware  under running water before I dip it.

 

I've switched to Mayco underglazes from Amaco whenever the colors are similar enough and that does seem to have helped. Guess I'll look at other brands for the few Amaco I haven't been able to duplicate...

 

Thanks, guys, it sounds like a plan :))

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Just a wild guess here but I'm wondering if some of the underglazes are fluxing a bit at 04 which is making the glaze not stick well to the pot? Some of the spectrum underglazes I use are fluxxy  at 04 but at 06 they don't. 04 and some of the underglazes resist the glaze a bit. I've also had the spectrum pink crazed coming out of the 06 bisque fire but is fine after firing to ^6, your webbing does somewhat follow a crazing pattern doesn't it, at least on the handle? So with my logic I would put it down to a combination of those two things; underglazes fluxing a little plus some crazing of the underglaze.

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Carol have you tried another brand of underglaze, there can be a big difference from brand to brand in how they work.  Have you tried spritzing some water on the underglaze before you put the clear on it.    Denice

 

If it's the underglaze, I just had to start doing my decorating on leather hard clay, rather than the bisque. It fixes the problem just fine.

I do rinse the bisque ware  under running water before I dip it.

 

 

 

I run my bisqued pots under water and wet sand them, and then I dry them out for a couple of days before glazing. Otherwise the glaze does WEEEEIRD stuff and takes forever to dry, especially over underglazes that have been fired once. If you do this and then put directly into the kiln it can even "fall off" because it is just not adhering well to the surface of the pot. 

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Carol have you tried another brand of underglaze, there can be a big difference from brand to brand in how they work.  Have you tried spritzing some water on the underglaze before you put the clear on it.    Denice

 

If it's the underglaze, I just had to start doing my decorating on leather hard clay, rather than the bisque. It fixes the problem just fine.

I do rinse the bisque ware  under running water before I dip it.

 

 

 

I run my bisqued pots under water and wet sand them, and then I dry them out for a couple of days before glazing. Otherwise the glaze does WEEEEIRD stuff and takes forever to dry, especially over underglazes that have been fired once. If you do this and then put directly into the kiln it can even "fall off" because it is just not adhering well to the surface of the pot. 

 

 

 

Just a wild guess here but I'm wondering if some of the underglazes are fluxing a bit at 04 which is making the glaze not stick well to the pot? Some of the spectrum underglazes I use are fluxxy  at 04 but at 06 they don't. 04 and some of the underglazes resist the glaze a bit. I've also had the spectrum pink crazed coming out of the 06 bisque fire but is fine after firing to ^6, your webbing does somewhat follow a crazing pattern doesn't it, at least on the handle? So with my logic I would put it down to a combination of those two things; underglazes fluxing a little plus some crazing of the underglaze.

 

Hey Giselle and Min,

 

Thanks for your suggestions!  

 

Giselle, when I rinse the bisque ware, I do it quickly and it seems to dry fast - at least on the surface.  I'll try waiting next time and see if that helps :))

 

And Min - when I read about reducing the bisque to ^06, ding ding ding! Everything just felt right -I think you've nailed it.  Because this weird webbing happens with specific colors, I'm thinking you're right, they may be fluxing.  It does't happ with, say orange - but orange tends to peel away from edges and leave little spaces uncovered...  So maybe... Fingers crossed!  

 

Thank you all - I appreciate your help!

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Hey Carol,

 

ding ding ding back at you,  :) , "It does't happ with, say orange - but orange tends to peel away from edges and leave little spaces uncovered..."   if this underglaze is being applied in the same way as the others, which don't peel away, and it's doing that then I would say it's shivering. I would swap it for another orange. Spectrum neon orange shivers on my clay but their other orange colours don't. I contacted them and they said they use a different base for the neon orange, so I would say it's possible other manufacturers do the same thing.

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I have noticed this type of patterning when reglazing a piece if there was crazing after the first cone 6 firing. (I sometimes check out a suspect fired piece by dipping in a glaze to see if I see these webs)  I assumed the new layer was entering the fissures. And the refire still might not fix the crazing. So the idea that the underglaze has fluxed and is now crazed makes sense.

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Hey Min & Pleasant Pottery!

 

So far, things are looking hopeful. I did a bisque fire last night to ^06 and the glaze went on sooo smooth! Not a single webby area, even though two of the pieces were in the same turquoise that has always produced the webbed pattern. Yay! And thank you! I'm firing to 5 with a 10minute hold that pushes it to 6, so we'll see tomorrow... iIt was reassuring to hear about your experience, Pleasant Pottery - clever of you, too. :)

 

And Min, about the orange underglaze. I had the same thought, that I should try a different brand. Amoco's Flame Orange is encapsulated (read costly) and I love it. Mayco doesn't have anything like it, so I ordered ... yup... Spectrum's Neon Orange. LOL. Maybe it will be okay on my clay body, which is Laguna 609 - what do you use? Or maybe I'll look some more...

 

Did I say thank you? This has been a nuisance for ages and I'm optimistic this will resolve it. So a Huge Thank You!

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about the orange underglaze. I had the same thought, that I should try a different brand. Amoco's Flame Orange is encapsulated (read costly) and I love it. Mayco doesn't have anything like it, so I ordered ... yup... Spectrum's Neon Orange. LOL. Maybe it will be okay on my clay body, which is Laguna 609 - what do you use? Or maybe I'll look some more...

 

Hi Carol,

 

Glad it seems to be working out for you :)

 

The Spectrum Neon Orange shivers on Plainsman 370, it's a Canadian clay, low expansion. What I landed up doing was mixing it with either Spectrum Bright Orange #563, about 1/4 Neon and the rest Bright Orange or Speedball's orange in the same ratio. The Speedball doesn't seem as crisp as the Spectrum, I'm guessing their underglazes are clay based versus Spectrum's being frit based, could be wrong here but that's what they look like to me. The blended colours are not as in your face bright as the original Neon but I actually prefer them a bit toned down and the neon doesn't shiver when cut with the other u derlazes.

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about the orange underglaze. I had the same thought, that I should try a different brand. Amoco's Flame Orange is encapsulated (read costly) and I love it. Mayco doesn't have anything like it, so I ordered ... yup... Spectrum's Neon Orange. LOL. Maybe it will be okay on my clay body, which is Laguna 609 - what do you use? Or maybe I'll look some more...

Hi Carol,

 

Glad it seems to be working out for you :)

 

The Spectrum Neon Orange shivers on Plainsman 370, it's a Canadian clay, low expansion. What I landed up doing was mixing it with either Spectrum Bright Orange #563, about 1/4 Neon and the rest Bright Orange or Speedball's orange in the same ratio. The Speedball doesn't seem as crisp as the Spectrum, I'm guessing their underglazes are clay based versus Spectrum's being frit based, could be wrong here but that's what they look like to me. The blended colours are not as in your face bright as the original Neon but I actually prefer them a bit toned down and the neon doesn't shiver when cut with the other u derlazes.

 

 

Speedball orange is quite dark for an orange. If you want brighter try their yellow-orange. It's a nice bright orange, but not neon-obnoxious.

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