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Underglazes should be applied when?


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#1 Pugaboo

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Posted 07 March 2013 - 11:42 PM

Just read this on another website... Is this true?

"When to Apply- Underglazes should be applied to dry greenware. If greenware is still damp when applied, the underglaze colours may chip off after firing."

I've read here and elsewhere that underglazes can be applied to leather hard clay all the way up to dry greenware. Some even say they can be applied to wet clay if you can do so without brush strokes ruining surface. So which is true? If I paint on leather hard clay and then allow the underglaze and clay to basically dry together until bone dry and ready to bisque fire will my colors chip off?
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#2 clayshapes

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Posted 08 March 2013 - 12:12 AM

I apply to leather hard greenware. Never dry greenware. Too fragile. I often wait to apply to bisqued pieces as well. I see no difference in color when I do this.

#3 bciskepottery

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Posted 08 March 2013 - 12:14 AM

I've applied underglaze at the leather hard, greenware/bone dry, and bisque stages. I prefer applying before bisque; that allows me to do any touch ups before glazing.

#4 DAY

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Posted 08 March 2013 - 06:55 AM

I put the underglazes on "wet" clay- fresh from the slab roller.

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#5 Doulla

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Posted 08 March 2013 - 07:15 AM

I usually paint on the underglazes at the leather hard stage which I find the best time. I have also put them on before this and when bone dry. I have never had underglaze chip off. I then add more colour if necessary after the bisque firing.







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#6 Marcia Selsor

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Posted 08 March 2013 - 07:53 AM

I apply at leather hard stage if I plan to carve through the underglaze. If not, I apply it on dry greenware for certain techniques.
It all depends what you are doing.

Marcia

#7 scoobydoozie

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Posted 08 March 2013 - 08:18 AM

This is an interesting question as ceramics is still changing.... I attended a Mayco Knowledge Workshop last summer where we used underglaze (true underglaze, not their Stroke & Coat) on cone 04 low-fired bisque and then immediately applied their clear glaze on top without firing first. We then fired once to cone 06. The piece came out beautiful with no crazing, shimmering, pealing, cracking, etc. Mayco has reformulated their underglazes to allow it to be applied to bisque and clear glazed over before firing. It's truly amazing in my opinion. Mayco is doing a top notch job at innovating! Keep in mind, this only applies to Mayco underglaze that I know of...
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#8 neilestrick

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Posted 08 March 2013 - 10:10 AM

If underglazes are applied to leather hard or wet pots, they should actually bond even better, not flake off.

Any good brand of underglazes can be applied to wet, leather hard, bone dry or bisque ware. If you apply them to bisque you do not need to fire them before glazing, but you should let them dry overnight if you're dipping the clear glaze.
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#9 Jess

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Posted 08 March 2013 - 05:28 PM

Just read this on another website... Is this true?

"When to Apply- Underglazes should be applied to dry greenware. If greenware is still damp when applied, the underglaze colours may chip off after firing."

I've read here and elsewhere that underglazes can be applied to leather hard clay all the way up to dry greenware. Some even say they can be applied to wet clay if you can do so without brush strokes ruining surface. So which is true? If I paint on leather hard clay and then allow the underglaze and clay to basically dry together until bone dry and ready to bisque fire will my colors chip off?


I use the AMACO velvet underglazes and have applied them at all stages from wet to bone dry and on bisque ware. I have not had any trouble with them flaking off but I suppose if you really glop it on they might. You may want to make a few test tiles with the underglazes you use just to be sure how they will react.

#10 Pugaboo

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Posted 08 March 2013 - 06:16 PM

LOL okay I guess that little tidbit falls under the Catagory of not believing everything you read.

I am using Amaco LUG underglazes but have only just started using them and have not even seen them fired to bisque yet. When I read that I was just worried that the few pieces I have painted and left drying in class had been done incorrectly and were going to flake off since I painted the underglaze on at the leather hard stage.

Thanks for all of you that let me know the accepted ways in which to apply underglaze to clay.

Terry
The world is but a canvas to the imagination - Henry David Thoreau

#11 Jess

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Posted 08 March 2013 - 07:04 PM

LOL okay I guess that little tidbit falls under the Catagory of not believing everything you read.

I am using Amaco LUG underglazes but have only just started using them and have not even seen them fired to bisque yet. When I read that I was just worried that the few pieces I have painted and left drying in class had been done incorrectly and were going to flake off since I painted the underglaze on at the leather hard stage.

Thanks for all of you that let me know the accepted ways in which to apply underglaze to clay.

Terry


I've tried a few of the AMACO LUG underglazes as well and I didn't have any problem with flaking no matter when I applied them.

#12 Mossyrock

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Posted 08 March 2013 - 10:09 PM

I use the AMACO velvet underglazes and have never had a problem with them flaking off the piece. I've used them on all stages of raw clay and on bisqued pieces (depends on the end result I want to achieve). As a note, the youth coordinator at the school where I use to work would let the children paint underglazes on their 'just created' pieces, then after they dried, she would apply a clear glaze and fire. They turned out great.
Brenda Moore
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#13 Marcia Selsor

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Posted 09 March 2013 - 08:37 AM

I mix Glomax with my porcelain decorating slip, i.e. slip made from my clay body. By adding Glomax, Calcined Kaolin, it doesn't shrink as much and does not flake.
I am after an opaque color and the bone dry surface sucks in the slip to achieve this affect. So as I said, it all depends on what you are trying to do.


Marcia




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