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Hi, Robb! This is something that can be quite tricky and I am happy to share with you my experimentation with getting clear crisp lines. 

 

When I want a really crisp line I like to carve the design in when it's leather hard, because not only does it give texture but it gives the glaze a little well to catch in. I almost never have drips or runs when I do this.

 

Another very important thing is to allow each color of glaze to THOROUGHLY dry before applying the other. Then when you apply the other, if it drips onto the first color, I find that if you wipe it off right away it wipes away the first glaze too. So I wait for the second color to dry and then gently chip it off, stopping when I get to the first color underneath. I do a lot of glazing the interior one color and the exterior another and when I do this I really want a very clean line where the glazes touch but I do not want overlapping. 

 

If you're firing at a low fire like 05, I have had very good results with painting the lighter of the two underglazes on, allowing it to dry FULLY and then painting the darker color over the top. This requires that you experiment with your colors to see how they do layered over each other.

 

If you're working with Cone 5-6 (which is my temp range) another technique you might try is using underglazes on green ware, Velvet Underglazes from Amaco, or slips stained with Mason stains. Also, I have had really excellent results with wax resist mishima and carving. The wax resist mishima technique: I paint the item with wax resist at leather hard. When the wax resist has set I carve through the wax to the clay, then when it's dry, paint on underglaze or slip before bisque firing. In the second firing I will glaze certain portions and then carefully wax resist before applying the other color of glaze. You need to be very careful with this, however, because if you overdo the wax resist you will get a bare spot, which looks terrible when you're using darker glazes. 

 med_gallery_67168_1162_186117.jpg

 

Pie plate decorated with wax resist mishima, inlaid with white slip and then glazed with clear ^^. 

 

med_gallery_67168_1162_787824.jpg

 

^^ Teapot decorated with wax resist mishima with underglaze inlay for the leaves and stems, then after bisquing I glazed only the flowers and applied wax resist before applying clear to the rest of the pot. 

 

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Thanks Giselle! Appreciate all of the info and the beautiful photos of your work.

 

I'm trying to put a clear gloss circle on the side of a bowl surrounded by a med blue glaze and the edge is not sharp at all. I'm thinking of buying some circle labels to use as a positive or negative. It may mean a couple of firings.

 

Any more insight?

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Not that my answer is going to be helpful but sharp lines of separate glazes come at a cost i not willing to pay - time and patience. I have tried all that Giselle said. I have also tried using newspaper. And like wax resist but made of rubberlike substance that u need to take off before firing. Forget what its called.

 

Honestly when i want sharpness i think of. Coloured slip. Sharp lines. No running. Clear glaze on top. Low fire glazes don't run usually depending on glaze and application.

 

Multiple firing might be the easiest way to go. Easier to clean the edges.

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The first thing is picking the right glazes. Usually, I have found that using more matte glazes next to each other is best because they tend to stay put and they don't move as much. The firing temp is also mportant. If you over fire the kiln all the glazes will melt more and move more. You're going to have to experiment to find the winning combination. Using a clear glaze will make getting a clean line more tricky. It's going to want to blend at least in part with anything next to it. I carve a line to separate where the clear will meet another glaze. The acts almost like a catch for the glaze. It can pool a little without leaving the line as long as the temp is right.

 

You can see on my cup the clean line between the purple in the middle and the clear on the bottom over my butterfly design. Had I put the light glaze on the top portion in the middle, it would have run down and messed with my design.post-65567-0-88466700-1469410087_thumb.jpg

post-65567-0-88466700-1469410087_thumb.jpg

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"w to stop Bleeding" place that in the search box.

A post by Paul Lewing is a great answer.

I've tried to copy and paste for you but that is not working.

 

"The solutions to your problem that have been proposed have all been process or physical fixes, but the root of your problem is chemical.  If you want glazes to bleed a long way into each other, they need to be very dissimilar.  Conversely, glazes that are similar will bleed into each other less.  And the key area of difference is Si:Al ratio.  If the two have ratios have difference from each other that is greater than 6 they will definitely bleed a lot.  For instance if one has a Si:/Al ratio of 5 and the other has a ratio of 12, expect a lot of bleeding.  This of course makes sense.  One is deficient in silica, the other is deficient in alumina, so the go looking for what they need in the other.

So... bottom line, if you want no bleeding at all, your best bet is color variations on the same glaze.  Doesn't matter what glaze it is.  The the only variable will be how much of a flux or refractory the colorant is in each different color variation"

Paul Lewing.

 

I went via Word doco

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Back in the '50s liquid wax resist was developed at the Archie Bray Foundation. When bernard leach and Shoji Hamada visited, Hamada took some back to Japan. David Shaner was director of the Bray in the 60' he used wax resist too.

here is a nice example 

http://www.asahibeer-oyamazaki.com/english/collection/016.html

here are some of Shaner's

http://www.jfranklinfineart.com/wp-content/uploads/2013/02/Shaner-Bowls.jpg

 

The glaze is applied. Then the wax. the glaze is washed off. The glaze under the wax remains. The next glaze is added. there is a clean line between the 2 glazes

 

Marcia

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