Making Pottery for the Garden

[Evan Goldstein]

Hello,

 

I currently throw stoneware and fire it to cone 6. If I wanted to throw large pots and keep them outside overwinter in NY, should I use a special clay or change my firing to avoid cracks?

I have a Skut Electric kiln.

 

Many thanks,

Evan

[neilestrick]

Your cone 6 clay should be every bit as vitrified as a cone 10 clay if it was properly formulated. However, pots in general do not do well outside in the winter, no matter what kind of clay you use. If they fill with water and it turns to ice, the expansion cracks the pots apart, whether or not it was actually absorbed into the wall of the pot or not. If you want to leave pots outside in the winter, at the very least they should be turned upside down. The only way to guarantee that they will survive winter is to take them inside.

[Doulla]

Hi,

 

 

 

I make pots and sculptures for the garden. I fire to cone 6 and have never had a breakage through weather. I am not sure how cold it gets in NY as I live in England. We have had a couple of bad winters recently with lots of snow and temperatures of -5. For the pots I use a heavily grogged crank clay and I think one of the most important things is the shape of the pot. It should be narrow at the bottom and wider at the top so that if the earth freezes and needs to expand it can do so without putting pressure on the pot. The pot also needs to have good drainage holes and it is best to lift it onto feet during winter so that it does not freeze to the ground. When planting the pot you also need to put a good bottom layer of gravel or broken pots to give good drainage.

[Karen B]

Hi Evan,

I use a specific cone 6 clay for outdoors. I am in Massachusetts, so you know it gets cold here. I have a large slab pot (with no bottom) around a small tree that has been outside for about 5 years with no sign of wear. This clay is called S707 and is sold by Ceramic Supply www.7ceramic.com. It is made by Standard. I didn't see it on the online catalog, but I called and they do have it. It has a Shrinkage of 12% and Absorption of 0.3%. It contains some grog and fires a nice brown. My cone 6 glazes don't work the same on this clay, so it needs testing, but slips with clear glaze work nicely.

[DAY]

Shape is important when frozen water is involved. My bird baths have shallow sides, so that the water rises up, rather than out, as it expands. If they truly are "pots"- as in flower pots, then they will eventually succumb to the same forces that turn mighty mountains in mole hills. . .

[Megaperplexed]

I live in North Georgia, so our winters are not as extreme as yours. We do end up with a lot more ice, I believe, and fluctuating temperatures which may cause more expanding contracting issues. I made several garden items, or some just ended up in the yard, from classes I was taking. Fired to cone 6. It took 5-7 years before small cracks in the glaze to start appearing and over 10 years for an official crack on the first one. The one that is still surviving after 15 years is a coiled (thick) sculpture that does not catch any water and is not glazed on the inside and where it touches the ground.

 

I don't know if that is helpful at all, but I was really surprised at how long they lasted through the elements.

 

 

 

[Joy pots]

Hello,

 

I currently throw stoneware and fire it to cone 6. If I wanted to throw large pots and keep them outside overwinter in NY, should I use a special clay or change my firing to avoid cracks?

I have a Skut Electric kiln.

 

Many thanks,

Evan

 

 

I live in Manitoba Canada and I loosen the dirt inside my pots and place them either on their sies or upside down. We can get up to -40 in the winter and these pots haven't broken over several winters. The clay is a medium body stoneware fired to cone 6. I've also used raku clay and high fired clay all fired to cone 7 without a problem. The pots are both thrown and hand built.

Joypots