Outdoor Work And Freeze-Thawing

[Kohaku]

I have a potential opportunitiy to create an outdoor installation.

 

If I work in clay, I'll obviously need to worry about the resiliency of the piece (it would be installed in a cold climate). I've read a couple articles (here's a short one from Digifire).

 

Porosity seems to be a key factor. I've seen some mention of closed porosity, however- linked to the idea that addition of fibrous material to the clay body can actually increase resiliency.

 

One measure that I will take, if I do this, is to make the installation modular (keeping the components smaller).

 

However, I was wondering if anyone had grappled with this issue, and whether they have any suggestions?

 

[Mark C.]

Your clay need to be vitrified to survive the freeze.

Mark

[neilestrick]

As Mark said, vitrification is the single best way to avoid cracking in a wintery outdoor environment. If you're making a 3 dimensional object, also make sure that water cannot puddle and freeze on the piece, as the ice will crack it.

[Kohaku]

OK- thanks. Just to add a wrinkle to things- what if the piece was rendered permeable through inclusions in the clay?

 

For context, I'm exploring the idea of bio-sculpture (sculptural works that are integrated into natural settings and perform an ecosystem function). Jackie Brookner does this type of work in concrete.

 

Ceramic forms- made from clay bodies with coffee grounds- have been used as bio-filters in some developing countries. I was considering making a form from this type of clay body and installing it in a run-off zone (where it would perform a filtration function, as well as being educational).

 

I could certainly fire the form to full vitrification... but it would still have the inherent porosity. Recipe for disaster? What if the size of individual components was minimized? (Perhaps with a mosaic-style surface over an armature)?

 

I know these are some off-the-wall questions, and I appreciate the feedback.

[neilestrick]

Water expands as it freezes, so if there are small openings in the clay due to burned out organic matter, that can fill with water, you will get cracking when ice forms. You want a form that cannot harbor water, and won't absorb it either.

 

If it's in a run-off zone, does that mean it will be partially submerged in water? Will the water freeze in winter?

[Kohaku]

Water expands as it freezes, so if there are small openings in the clay due to burned out organic matter, that can fill with water, you will get cracking when ice forms. You want a form that cannot harbor water, and won't absorb it either.

 

If it's in a run-off zone, does that mean it will be partially submerged in water? Will the water freeze in winter?

 

There are a couple options. The form(s) could be built on a piling (or other substrate) and be above water. It could be placed in an area that's exposed to storm run-off, but not a perennial channel. Or... it could be placed in a streambed (partially submerged).

 

We're in the 'banana belt' of Idaho here, and surface water typically freezes to about three inches of depth- usually for no more than a few days. So- definite freeze thaw cycles, but only part of the form would be subjected.

 

I've considered other materials (concrete, etc) but the filtrative potential of the form is important, and a porous clay body offers some real advantages if I can get past the freeze-thaw problem. Maybe I just need to do some tests of different sized components...

 

I guess that I could do a modular build, and use non-permeable, fully vitrified components in the areas prone to freezing.

[Callie Beller Diesel]

Just for visual reference, I have two flowerpots here. On the left is a soda kiln misfire, stoneware that hit^10' and is glazed inside. In other words, a mature clay body but still kinda "open." On the right is a commercial terra cotta pot. Neither has been protected in any way from the weather in the last five years. Where I'm at, We frequently experience a 40* temperature variance in the space of a week, all winter. Because of local weather patterns, we can be at -30C one day, and +10 the next, and vice versa. (Sorry, my grasp of Fahrenheit sucks at more "everyday" temperatures.)

So pretty harsh freeze thaw cycle.

 

My point is, depending on how much degradation is acceptable, and how often you want to replace any given modular piece, some porosity might work.

 

 

[Mark C.]

It a big experiment that may or may not work.May last a winter or 3??? its a big unknown.

(how much degradation is acceptable, and how often you want to replace any given modular piece, some porosity might work. )Was a great statement.

but until you leave it out there you will not know

What I think is the issue is how long you expect it to last VS how long until it degrades.

 

With what I know now about clay- I would want it to last and that means vitrified

anything less is asking for failure sooner than later.

sometimes saying no is best for some opportunities.

 

Your meduim If I recall is Raku and its not made for outside freeze-thaw cycles.

Mark

[Marcia Selsor]

you need to do an absorption test. weigh a fired tile dry. Then boil it for 2 hours in water. Wipe it off and weigh again.

the weight difference should not be more than 3% . between 1-3% is acceptable.

 

Marcia

[Kohaku]

It a big experiment that may or may not work.May last a winter or 3??? its a big unknown.

(how much degradation is acceptable, and how often you want to replace any given modular piece, some porosity might work. )Was a great statement.

but until you leave it out there you will not know

What I think is the issue is how long you expect it to last VS how long until it degrades.

 

With what I know now about clay- I would want it to last and that means vitrified

anything less is asking for failure sooner than later.

sometimes saying no is best for some opportunities.

 

Your meduim If I recall is Raku and its not made for outside freeze-thaw cycles.

Mark

 

Thanks.

 

I've worked in high fire... although Raku has certainly been dominant of late. For this project, I was considering high-fire elements with small (mosaic tile style) Raku accents. None of the Raku stuff would be structural or sizable.

 

Thanks for the test advice Marcia- I'll do that.

 

I'm thinking that one option may be to craft an external, modular surface skeleton... and then have internal elements (non-structural) made from a porous, filtering clay body.

[Bob Coyle]

I made a whole bunch of hummingbird " ant traps" that failed because of the geometry of the piece. As mentioned, ice expands when it freezes. Geometry counts, as does porosity. You may have your piece above the water line, but it may fail at the next freezing rain that falls.