I teach high school and I am having my students design clay sculptures that will go outside in our courtyard. I have never built for out side so I have a couple concerns. First, we have large amount of stoneware... is this alright to use. What type of glaze is best for out door use. Do I need to worry about the outside elements. We live in the Midwest so we get rain, freezing rain, snow, heat, and everything in between. Will the sculptures expand and contrast and causes cracks. I welcome any and all advice on this topic. Thank you in advance.
Posted 19 May 2014 - 11:26 AM
If glazing, you need something that fits well on the body you are using. Crazing and shivering will allow moisture to get under the glaze. In freeze thaw cycles, the glaze may start coming off. My limited experience with stoneware, outside, in the conditions you describe usually has resulted in some breakdown somewhere in the system. Though it might take years or one winter!
That can be part of the beauty and education of a piece outside - to see how it changes over time.
Black Kitty Pottery
Posted 20 May 2014 - 11:40 PM
Posted 21 May 2014 - 10:04 AM
My problem was that I made these pieces out of low fire clay that I had sitting around after a class I taught. Just fired to cone 05. They were glazed inside and out but they still broke. If I had used cone 6 clay and glaze I probably would have had better luck, although they had some pretty freeze unfriendly geometry to begin with.
Posted 21 May 2014 - 10:49 AM
Thanks for the help. We are using cone 6 stoneware. Do you think under glazes with a clear coat over them will be alright to use?I don't have much experience with stoneware so if under glazes what would be best? I also don't mind covering during our snowy season which may help????
Posted 21 May 2014 - 11:04 AM
The snow isn't the problem it's moisture getting into the clay then expanding when frozen that cracks the piece. I would make up a couple test pieces that would fit in a kitchen pot, then boil them for 5 hours, cool in the water overnight then wipe them off and put them in the freezer.
Posted 27 May 2014 - 10:12 AM
Posted 28 May 2014 - 05:36 PM
Any place where water can collect in the sculpture and then freeze risks a crack. It's not the clay itself that will crack from the cold I believe. I've had lots of things outside, but it's the expansion and contraction of ice in a enclosed like space. So if the sculptures have places where water can pool even a little you risk cracking. I have several mosaics that we did in our school and we hung them outside. As a precaution I caulked all the edges so water could not get in between the backing and the tile even a little or they might have not survived from ice and the expansion.
Posted 28 May 2014 - 06:38 PM
in addition you can try to locate the piece where it may be sheltered from the elements, especially soaking rain that freezes. you can try to design the piece so that it shunts off water as well..think about places where water might pool , and provide a way for that water to drain. simple things like this will help enormously. also make sure the piece is up off the ground, so it does not sit in freezing and thawing rain,ice snow, and moisture wicking up through the ground..
Revival Arts Studio
Posted 28 May 2014 - 06:42 PM
from your post, i just realized the sculptures may not be permanent. is this correct? i would advise sealing them with a good quality penetrating sealant. works on glazed or unglazed pieces. make sure it is a penetrating sealant, not those milky acrylic sirface sealants...if they are out there for a short time, this should be enough to keep them safe, especially if they are well fired to maturity at any temperature between high earthenware to stoneware...
Revival Arts Studio
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