This bust of Napoleon, from a party in Baton Rouge, was being damaged somewhat by the late afternoon sun. Because the sun was on the verge of disappearing behind the trees and buildings, we uncovered the piece. The white spot in the center of the carving is white ice on the back that I hadn’t gotten around to getting rid of just yet.

*updated 12/12/11



How long will it last?

This is a very common question, rivaled only by those such as “Is that ice?!” or “Did you make that?” The answer, of course, is: “It depends...”

The standard answer that I give is: “usually four to six hours,” but I always qualify this and explain that it depends mostly on the temperature. But it also depends on the airflow, humidity, mass and surface area of the sculpture, how cold the sculpture was when it was set, and whether or not it’s exposed to sunlight (like the piece above). It also depends on what you mean by “last.” Until it falls over? Until it’s melted away completely? I usually explain that it “lasts” until most of the detail is gone.

I’ve listed some factors that affect how long the ice will last, along with a brief explanation below.

Temperature

This is the biggie. A carving in a very warm room might last half as long as one set at room temperature. On the other hand, larger pieces that I’ve worked on in Alaska, Belgium, or Germany have been up for a month or more (in cold environments).

Humidity

The more humid the air, the more efficiently heat is transferred from the air to the ice. In New Orleans in August, carvings can melt VERY fast.

Airflow

This also can be very bad for your ice; a sculpture that I had positioned between two buildings faded very fast when the wind was channeled between the buildings. Don’t put sculptures near vents, fans, or air conditioners if you can avoid it.

Sunlight

Microfractures form inside an ice sculpture exposed to sunlight and as time goes on, they get larger and join together resulting in a sculpture that will collapse into a stack of shards. Extreme cold (about 15 degrees F) keeps this from happening. There are microfractures forming in the hat of the sculpture pictured above. Formation of these small fractures will make ice look “gray” and less crystalline. Carvers working in bright sunlight should shade their sculptures whenever possible. The fracturing effect of sunlight can be very strong and has resulted in many sculptures crashing in competitions.

Hot lighting

I’ve seen a strong light melt a hole right through an ice bar. Don’t put sculptures near hot stage lighting.

Sculpture Mass

With ice, size buys you time, as long as you pay plenty of attention to the supports of the sculpture.

Sculpture Surface Area

The shape with the least surface area is the sphere. Complex shapes with more surface area open themselves up to more exposure to heat and therefore melt faster.

Depth of detail

This is a balancing act. Light detail fades quickly whereas heavy detail in the wrong spot can make a sculpture structurally weak.

Original core temperature

The colder your sculpture is when at the start of the event, the longer it will last. However, a sculpture that’s too cold when it’s put out may fracture and will likely remain frosty for a while. By the way, the white spot on the Napoleon carving pictured above is not frost, it’s just white surface ice on the back of the sculpture that had yet to be removed before I took the picture.

Weather

Wind can knock sculptures down and it should be obvious what a little rain will do.



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Tags: temperature, weather, lighting, core temperature, competitions