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Juli Long

Glaze Is Grainy, Rough At Lip Of Mugs

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My stoneware mugs seem to be having major issues with their lips. Instead of the glaze breaking smooth over the lip it is rough and grainy just at the edges.

Im not sure if this is a throwing flaw from the chamois taking away too much clay leaving the lip rough or a glazing issue where the glaze breaks.

Either way, I must fix it because its not acceptable. Lips appear smooth after throwing, and I sponge  my 04 bisque before glazing. Firing to cone 6.

Hope someone has an answer!

juli

post-2478-0-35957400-1373639818_thumb.jpg

post-2478-0-35957400-1373639818_thumb.jpg

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Looks to me like the glaze is just running down/away from the rim of the mug. The natural unglazed stoneware is rougher than the glossy glaze, so when it pulls away you get the groggy texture of the stoneware.

 

I'd say put more glaze on the rim of your piece. Are you brushing this on? I always have problems with thin rims while brushing because they get wetter and less glazes adheres. Maybe an extra brushing just on the lip once the rest of the glaze is dry.

 

If you're dipping, it'll be hard to do without creating an obvious line, maybe use your finger to put some extra glaze on the lip.

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I think it is the glaze. The glaze you're using on the pictured mug has to move a lot to acheive the hare's fur look so it is running off high thin places. That's not clay that is making the lip rought but spots of glaze. Try other glazes. If you have, did you have the same problem with them?

 

Jim

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post-2478-0-95643000-1373646982_thumb.jpgWell, yes, it does happen with all three clays I use,,Trinity 6,and two Armadillo clays, a brown and a white.

The glazes are nutmeg, (pretty stable)l, and butterscotch over rutile blue(pretty runny). Now that Ive said it happen with all my clays, and glazes, It might be my throwing.

post-2478-0-95643000-1373646982_thumb.jpg

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Make sure the lip is rounded, with no sharp edges. Use a chamois to round it, rather than your sponge. The sponge will wipe away the fine particles and expose the large rough particles. The chamois will give you a smooth, rounded edge that will hold glaze well.

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Just threw a mug and left the lip alone, much better looking. I love a chubby lip, and I think I overwork the lip trying for a nice curve and chamois it to death bringing to much grog to the surface. Bad habits are hard to break, and this one ive been doing for ever.

Ouch, I wish it was the glaze.

Thanks everyone for taking the time to give input!!!!

juli

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Overworking the clay at the rim yes, but I don't think the use of the chamois is a problem. Using a chamois usually smoothes the slippery smaller particles over the courser ones at the same time compressing the clay . . . albeit a small amount.

mregecko likes this

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You know, I've never used a chamois to smooth the rim.  I have always used a flexible elephant ear sponge, or even just a standard cellulose sponge.

I may have to start with the chamois.

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You can also try using a very soft rubber rib, like the red ones from Sherrill, to do a final smooth-over on the rim.

 

Or, after bisque firing, use a stilt stone to grind down any rough areas...though this is tedious and makes a rather annoying noise...

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When I was teaching, I showed the kids the poorman's chamois-a small piece of folded over paper towel taken out the the garbage can. This works just about as well as a chamois, and is really cheap. However,  it can be a pain if it ends up in the slop. I have had times where I would be wire cutting clay and pull a piece of this through the clay, but then it happens with chamois too doesn't it.

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My chamois all have a small fishing bobber attached with a short fishing line. I think I got that idea on here! But after finding one in my slurry bowel, I got serious about implementation.

 

Alice

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I use a chamois. I have a friend who used the web between her index and middle fingers. Using a sponge if wet, can wash away the clay and bring up the grog. Not the surface you want on a lip. Just put a thick matter glaze one the lip and refire.

 

Marcia

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My chamois all have a small fishing bobber attached with a short fishing line. I think I got that idea on here! But after finding one in my slurry bowel, I got serious about implementation.

 

Alice

Sorry folks , but I really have to say something as I am rolling in laughter here. Isn't it intersting how the insertion of an "e" can change the whole meaninng of a post. :lol:

Nancy S. likes this

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---- And I gotta tell you, that's an 'e' that I add on a consistent basis! But THANKS for pointing it out! My spelling and typing both leave a lot to be desired!

 

Alice

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What's funny is, how many people read the post, and didn't even notice that, including myself.  The brain does a great job, of changing things, due to context. 

It's like those sentences, where they purposely leave out letters/ words, or add them in, and you don't notice, because your brain does the editing.

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Alice, please don't take offense. Even a spell checker would not have helped there. I was just having an internal brain giggle trying to tie the statement to some sort of cartoon.

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I had to reread the post to catch the "E", no telling how many typo's I trtail along behind. :lol:

 

Anywho, some years back I made a slip for just this reason using barnard clay subed for other clay in a cone 6 clay recipe that was very smooth and brushed on the rim  about the time for handles.

It added some contrast at the rim that the clay lacked.

Wyndham

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Pres - SOOOOO not offended. I was getting a giggle about you finding it funny. If you can't laugh at yourself, you're not a very interesting person...

 

Alice

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our guild has made bowls for the empty bowl supper for many years.  some time ago we had a member who ALWAYS printed neatly "Empty Bowel" and the year on the bottoms of her twenty donations.

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