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nancylee

Help! New Help With Nameplate Splitting Off

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Hi,

I am trying to make these mugs for Christmas, and I put the nameplates on, then dried the mugs slowly. Candled for 12 hours, then slowly bisqued to cone 05. They seemed ok, but then split when I glaze fired to cone 5.

 

Questions:

1. Can I reglaze split area and refire to cone 6? Might that correct this? And if to:

 

2. Why is this happening at the glaze firing, not the bisque firing!?

 

Thanks, I have to get these presents made! Seeing family this week!

post-6053-0-05483400-1387118906_thumb.jpg

post-6053-0-05483400-1387118906_thumb.jpg

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I think you are better off making new ones than trying to fix.  And there is no guarantee the refiring will fix the problem (and more likely will not). 

 

I think your issue is the thickness of the nameplate . . . it looks to be the same as the walls of the mug, which means that area is twice as thick as the rest of the mug.  When heating and cooling, that extra thickness is expanding and contracting at a different rate . . . resulting in the cracking.  Try to make the name plates thinner. 

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Since you are making them over, make the nameplates before you throw the ugs. Try to have them the same dryness as the mugs when you attach. It looks like they may have been wetter  than the mugs when you attached them. That would be what caused the cracking.

Also, what Bciske said.

 

Marcia

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Wow!! Thanks, Norm, for that physics and chemistry lesson, too!! 

 

With the extra ingredients, how do I get the ingredients into the clay? I know the gum is liquid, but the others? Do I put the gum into the clay, knead it, then add the other ingredients? Thank you again, for that very logical explanation.

Best,

Nancy

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Taking Norm's info one step further, you could throw a separate cylinder to use to cut the name plates from and then attach to your mugs; that would negate any possible issues with ends from rolled slabs wanting to bend up or separate during firing.  You'd be making a thrown nameplate, instead.  You could even take the cut nameplate, place it on a form to keep the rounded shape, add the name, then attach to the mug. 

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Roll your sprig very thin, like 1/16 inch thick or less. Then drape it over a cylindrical form similar to the curve of your mug, like a rolling pin, let it dry to almost leather hard before attaching. It needs to be able to flex just a little bit to attach it. The closer it is to the moisture content of the mug, the better. You can join it with regular slip this way.

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Draping over a cylindrical shape  works for my sprigging, are you pressing letters into the  sprigg to make the names? This too may cause invisible cracking which  appears  to the eye on the second firing, especially when the impression is done close to the edge of the sprigg.   2G's in Sprigg??. Thickness is an issue too.

Inadvertantly stretching the sprigg when applying tho pot may also be present.

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Call me lazy or safe or whatever, but why even have this extra piece to cause all these headaches in the first place? Why not just carve/stamp a cartouche of some sort, and then use your letter stamps for the individual names when your clay is less than leather hard and be done with it. I don't know, I guess I'm missing something here. I just don't get the extra slab of clay added for a name. I guess it's aesthetics, but it sure seems like a lot of heartache for a small payoff.

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My assistant makes add on's to her porcelain mugs a few times every year in a production run with many themes mostly for women in cycling.

I will say that thickness and timing and even drying (cover for 1 night after attachments) will cure this.They can be thick if the moisture is correct.

In this case you can see the theme is a downhill bike mug and the add on is a sprocket (Just peachy this is the reason for this ) thats why its not stamped into the mug so the glaze flows around the form and sets it off as a sprocket

There are cone at cone 10

I have only seen one or two crack in a few hundred and that was due to uneven clay moistures  and those where very thin forms.

Mark

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Hi,

Thank you all for your help! So I did the following:

1. Made the add-ons thinner, and, yes, I do stamp the names into them

2. Rounded them as they set up a bit

3. The mugs were drier so I hit the nameplates with the dryer for a minute or two

4. I watched a couple of videos about putting on handles, and was surprised at how much force the potter pushed the handle on with, so I really pushed and "massaged" the nameplate on.

5. I covered them overnight.

 

You are all geniuses! Thank you!

 

And Just Peachy, I don't really have any particular reason I do,it this way, except that I made a few and they sold, and people really do seem to like them, so even thought they are a pain, I keep making them!

 

Thanks all,

Nancy

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You are still early in the process. As you nail down the individual problems you have with a new form or idea, it becomes easier and easier. The good thing about this is that in the future you have this old learning and awareness to carry on into new projects.  Good luck on the potters journey.

Frank Hott, nancylee and Babs like this

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Call me lazy or safe or whatever, but why even have this extra piece to cause all these headaches in the first place? Why not just carve/stamp a cartouche of some sort, and then use your letter stamps for the individual names when your clay is less than leather hard and be done with it. I don't know, I guess I'm missing something here. I just don't get the extra slab of clay added for a name. I guess it's aesthetics, but it sure seems like a lot of heartache for a small payoff.

 

Doing the letters as a sprig is a nice deign element, as the sprig can be made a different color, or left raw with just the letters stained. See photo in Mark's post above. With the raised sprig, making it a different color than the rest of the mug is super simple, and all this is much faster than carving out a frame. It just takes doing a couple to figure out the right moisture levels for attachment. I can crank these out very quickly, like about 2 minutes for each one, from rolling to stamping to application.

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Another alternative to adding on a sprig is to create a stamp for frequently used signs. Place the stamp against the side and genly rub the clay on the inside of the mug to push it into the stamp. A blank frame can even be created this way and then impress the letters into the frame one at a time.

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