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Cecily's Techniques: Green Glazing and Firing

Because of the high price of energy here of late I've been experimenting with once firing my beads. The kiln I am using is a Skutt 1018-3"with computer which has the 3" soft brick to increase heat retention and, therefore, reduce firing costs. Even so, I figure if I can halve my firing costs I'll be ahead of the game. OK so why do we bisque? Well for most of us we do it because our teachers did it when we were in school. So why did they do it? They did it to reduce the likelihood of breakage during glazing and explosions during glaze firings. Both of these disasters tend to be exacerbated by inexperience which beginning students have in abundance. From hence comes the preventive action of bisque firing.

But beads are small and thin and, therefore, tend not to blow up when fired green. And I am finding that if I handle and glaze them in the leather hard state they seem to be able to take glazing without a lot of breakage or disintegration. When I brush the glaze on I'm using it in a somewhat thicker state than one would use for dipping. The glaze is something like the consistency of pancake batter. When I dip my work the glaze consistency is that of light cream. The glazes I've always used on my bisque ware seem to be working just fine on porcelain green ware. However, a word of caution, be sure and run some test glazings and firings before committing a large body of work to these techniques.

Minimizing the amount of glaze applied to the green ware can also help reduce disasters during green glazing so I've been working more and more with colored clays to add color and fine detail to my beads. Buying colored clays ready made is quite expensive so I make my own using my old faithful porcelain clay body recipe and mason stains. I'll be glad to share these recipes and some forming techniques for colored clay bodies in my next blog as we are running out of room in this one and I want to mention one more glazing tip.

Beads can be hard to hold for glazing whether they are green or bisque. So I use two very simple tools to help hold beads for glazing: skewers and bead tongs. Skewers one can pick up in a variety of diameters at grocery stores and gourmet cooking stores. Bead tongs, however, have to be made from spring wire (not dead soft wire). What I used for the ones pictured here was thin welding rod. I have the full set of pictures showing how to make and use bead tongs uploaded to my facebook fan page now. The photographs uploaded here just hit the highlights. Usually I use the skewers for upright brush glazing especially of fine detail. And I use the tongs for dipping a single coating of glaze on a bead that will be fired dry foot. Since the tongs adjust to most hole sizes automatically while one has to fit the skewer to the size of the bead hole I will also use tongs for beads with odd sized holes. One very important thing to remember about using both bead tongs and skewers is that the bead at the leather hard stage is still drying and shrinking. Do not leave the bead on either tool to dry to bone dry. They will crack on the tool. Pull them off just as soon as you can.









Marla asked that I upload pictures of some finished pieces that were glazed green so here they are. The petals of the Hawaiian Hibiscus Necklace were brush glazed at a stage beyond leather hard but still moist with a white glaze. I made the stamen and anthers out of yellow colored porcelain and left them unglazed. The finished flower looks exactly like the ones I glazed in bisque. I know this because the commission was for 5 identical necklaces and I miscounted. So this is the necklace I had to glaze green. It is 3 1/2" in diameter and varies in thickness from 1mm on the edges to 2 or 3 mm in the center. Since I was dealing with something this thin I used one glaze and brushed quickly and got out before I started compromising the integrity of the clay.

The Beach Comber's Focal Bead was one that I demonstrated using the linoleum blocks in my last blog. It has a dark coral red glaze brushed dry to high light the texture and a clear rutile glaze brushed on top of that. It was fired dry foot on its rim. It is a convex oval 2" by 1 3/4" and 4 mm thick. With this much thickness to deal with I was able to apply two coats of glaze.
Hope this is of some help to you all in the constant fight we all have to make our art profitable. And if you have any questions please let me know and I will try to be of assistance. I can be contacted at the following: http://www.porcelainjazz.etsy.com or http://www.facebook.com/porcelain.jazz







7 comments:

  1. Excellent tutorial and wonderful ceramic pieces I am particularly fond of flowers and that one is totally beautiful

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  2. Ok, I have NEVER seen those bead tongs before! Where did you get those? What a great tool.

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  3. Love the post Cecily. Always something new and cool to show. Thank you!

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  4. love the tongs did you make them>? How do you keep the glaze out of the bead hole?

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  5. one more question: Why leather hard and not bone dry?

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  6. Work of our hands. The glaze does indeed go into the bead hole. One usually uses bead tongs for dry footed beads if one is dipping. That is they sit on their dry bottoms on a shelf in the kiln. It's an alternate method to bead trees and wire racks. Also the tongs can be used for brushing glazes on a bead as well, which is one method of keeping the hole clear of glaze. The other method of keeping a hole clean of glaze is to fill the hole with wax or paper to keep the glaze out when you dip the bead.

    Why leather hard? ..... Most clays are stronger when they are leather hard. Therefore, breakage is less likely. Also dry, green clay disintegrates easily in liquids and absorbs an awful lot of glaze. By comparison leather hard clays may get a little gooier but they usually don't absorb too much water and fall apart. Most people who do slip glazing for vapor and wood firings prefer to apply them in the leather hard or slightly drier stage for the same reasons. Usually they will apply them immediately after trimming the form.

    Hope this helps. Sorry to be so late in replying. Have been out of town.

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  7. Awesome... I really love the way you write your article here... And also it shows facts which I like. Thanks for sharing this.

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