fruch Posted May 19, 2014 Report Share Posted May 19, 2014 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. Link to comment Share on other sites More sharing options...
williamt Posted May 19, 2014 Report Share Posted May 19, 2014 Stoneware should be ok. When fire to its maturity temperature stoneware is usually not very absorbent. You don't mention which stoneware you are using, but you should make sure it's one that doesn't absorb water at more than 1 or 2 percent. I'm talking in the cone 6 range. 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. Lee Link to comment Share on other sites More sharing options...
Marcia Selsor Posted May 19, 2014 Report Share Posted May 19, 2014 You should probably do a freeze proof test on the stoneware. Marcia Link to comment Share on other sites More sharing options...
Bob Coyle Posted May 20, 2014 Report Share Posted May 20, 2014 You should probably do a freeze proof test on the stoneware. wish I had done that before I made a dozen hummingbird feeders that all broke because of ice expansion when we had a late freeze. Link to comment Share on other sites More sharing options...
Joy pots Posted May 21, 2014 Report Share Posted May 21, 2014 I have several pots outside all winter that have withstood -50c. The planters, I remove the soil & turn upside down to assure there is no water or frozen snow or ice able to collect inside. The bird feeders hang on branches all year. These pots are all cone 6 stoneware. Link to comment Share on other sites More sharing options...
Bob Coyle Posted May 21, 2014 Report Share Posted May 21, 2014 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. Link to comment Share on other sites More sharing options...
fruch Posted May 21, 2014 Author Report Share Posted May 21, 2014 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???? Link to comment Share on other sites More sharing options...
Min Posted May 21, 2014 Report Share Posted May 21, 2014 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. Link to comment Share on other sites More sharing options...
Joy pots Posted May 27, 2014 Report Share Posted May 27, 2014 The pots I keep outside are not all glazed. The main point is to keep them dry as Min said. Joy Link to comment Share on other sites More sharing options...
meisie Posted May 28, 2014 Report Share Posted May 28, 2014 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. Link to comment Share on other sites More sharing options...
stephsteph Posted May 28, 2014 Report Share Posted May 28, 2014 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.. Link to comment Share on other sites More sharing options...
stephsteph Posted May 28, 2014 Report Share Posted May 28, 2014 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... Link to comment Share on other sites More sharing options...
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