Chapter 2 Understanding the medium: the science of ice.
After reading this chapter, you will be able to:
* Explain the transformation of water into ice
* Explain the process of bending ice
* Discuss how and why ice is tempered before sculpting
* Describe how to prevent thermo-shock to a block of ice
* Summarize the use of ice blocks in early America
* Identify three methods of forming ice blocks and sculptures
* Discuss the pros and cons of using colored ice
* Discuss the effect changing weather conditions have on ice
Key Terms and Concepts
circulating tank method
molded sculpture method
weight to mass ratio
brine tank method
OUTLINE Water into Ice * Bending Ice Tempering * Common Methods Used for Tempering Ice Ice Usage in Recorded History Ice Harvesting in America * Natural Ice Making the Medium: The Manufacture of Ice * Commercial Ice * Colored Ice The Perfect Block Artist Profile
Ice, in the form of glaciers, covers between 25 and 3 5 million square meters of our world. During the Pleistocene Epoch, some glaciers spread from the Arctic to bury and subsequently erode parts of Asia, Europe, and North America. By 18,000 years ago, this ice sheet had spread as far south as Illinois, Indiana, Ohio, and northern Pennsylvania. The impact on the topography as a result of the movement of great sheets of ice remains visible today, particularly in central New York and throughout the Great Lakes region. In their retreat, the glaciers left behind one of the most important elements on earth: water.
WATER INTO ICE
Water's physical properties are unique. Water is the only natural substance that exists in all three states at temperatures normally found on earth: liquid (water), gas (steam), and solid (ice). The term ice can refer to the frozen form of many substances, such as carbon dioxide, which in its frozen form is dry ice. However, when we discuss ice in this text, we are referring to frozen water.
When absolutely still, pure water can be chilled to 15[degrees]Fahrenheit (F) before ice forms; however, since water under natural conditions is usually disturbed or contaminated, ice usually forms at about 32[degrees]F. When water freezes, ice crystallizes in a hexagonal system that refracts the light in pleasant, eye appealing ways when cut, similar to a glass prism. The angles between corresponding faces of any two crystals are always identical. In this the ice sculptor has an advantage over the wood carver-ice has a crystal lattice that allows for clean and predictable fracture lines.
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Water is also unusual in that the solid form is less dense than the liquid form. When ice forms, it takes up about 9% more space than it did as liquid. This expansion occurs when water molecules move farther away from each other as each crystal forms. Air is captured between the crystals, which gives ice a slightly lower weight to mass ratio than water. This is why ice floats in water.
The actual molecular structure of ice changes at various temperatures. At 16[degrees]F, ice has the same density and volume it has at 32[degrees]F. However, from 16[degrees] to 24[degrees]F, it expands with heat. Upon reaching 24[degrees]F, it begins to contract. Then, at 32[degrees]F, it begins melting and continues to contract until it almost reaches 40[degrees]F, when it again begins to expand.
This knowledge is important to the ice sculptor because the ice block will react differently to cutting when it is at various temperatures. The relative texture of the block will change from soft to hard and back to soft again when the block's temperature fluctuates by only a few degrees.
Ice bending is a phenomenon that until recently had been considered something of an urban legend among ice sculptors. Those who have lived and worked around ice long enough have observed ice in its many states of development, whether as a frost-coated blade of grass, a branch shrouded in ice, or an icicle hanging from a roof edge. However, bending of ice is a rare occurrence, since many conditions must occur simultaneously to produce a noticeable bend.
Existing ice must first be slowly warmed to a temperature just under 40[degrees]F to soften it without its quickly melting. There must also be sufficient weight on one end to create a limited amount of gravity-induced tension, but not so much as to snap the ice. To illustrate the process, lay a 1/2" diameter rod of ice on a table with the short end secured to the tabletop by a weight, and the long end allowed to hang over the table edge.
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As the ice warms to nearly 40[degrees]F, it will start to expand. This expansion will be directed towards the path of least resistance. The natural gravitational weight of the extended rod will cause the ice to expand and droop downwards. However, the bowing will actually decrease the gravity-induced tension, and the bending process will begin to slow. The average length of time to produce a 90-degree bend in a 1/2" diameter rod of ice at 40[degrees]F is approximately 2 1/2 hours.
In order for the sculptor to safely remove ice pieces from a full block without the fear of cracking and other temperature-induced problems, whether by saw, chisel, or power tool, the temperature of the ice must be consistent with the temperature of the air around it. For years, sculptors carving in spaces above 32[degrees]F have learned to temper ice blocks by slowly warming them up to room temperature.
Common Methods Used for Tempering Ice
Ice is generally formed in "ice cans" held in brine solutions that are set at 15[degrees]F, or in Clinebell tanks that freeze water at lower temperatures. However, the ideal temperature for sculpting is 26[degrees] to 28[degrees] F, when the ice is compacted, pliable, and less likely to shatter.
Loading Dock Method
One common method of tempering ice is to cover the frozen block with a large plastic bag, such as one used for leaves or garbage cans, and allow the block to warm to the surrounding temperature. This practice often occurs in an area like the loading dock of a hotel or kitchen, and usually takes 2 to 4 hours, depending on the ambient temperature. The sculptor then proceeds to sculpt in that same area when the ice is ready and safe to cut. However, in some warmer climates, this practice maybe impractical due to rapid deterioration of the ice. Wind, blowing debris, and rain can also have a sudden negative impact on the block.
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Walk-in Cooler Method
A second method for tempering ice involves warming the block more slowly in a walk-in cooler. The sculptor carefully transfers the frozen block from a walk-in freezer to a large walk-in refrigerator, and allows the block to warm to slightly below the freezer temperature. The block is also covered with a plastic bag with this method. This procedure works best when the sculptor has planned ahead and allowed sufficient time for the process, which can take 8 to 16 hours.
When the ice becomes soft and completely free of all frost, the sculptor should be able to place a wet paper on the ice block and remove it without the paper sticking. If the paper tears when it is pulled off, it is still too cold to carve safely.
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Although acceptable, these are not the only methods available for tempering ice. The key is to keen the internal temperature of the ice consistent with the temperature of the external environment. This can also be achieved by sculpting inside a walk-in freezer, a walk-in cooler, or outdoors on a cold day. It does not matter if the ice is soft and warm or hard and cold, the air outside the block must be the same as inside the block. Failure to balance internal and external temperatures can cause thermo-shodk and results in severely cracked and weakened ice. Contact with metal, such as a chain saw blade or router bit, or water can also crack the ice. These materials retain heat and can induce thermo-shock problems similar to those caused by warm, moist air.
ICE USAGE IN RECORDED HISTORY
It is not known whether during prehistoric times man used ice as we use it today. Obviously, no records were kept to provide such insight; we can only conjecture about its use. However, mention is made in the Chinese Book of Songs, written about 600 B.C., of how ice was harvested and stored in ravines covered with insulating straw-primitive icehouses. Hippocrates wrote of "the pleasures of drinking out of ice" in the 4th century B.C. Alexander the Great had trenches dug and filled with ice and snow to cool hundreds of wine kegs before each of his battles. And historians mention Roman references to ice and snow being used to chill beverages and conserve foods as far back as 52 B.C. when, reportedly, oysters were served on a bed of snow gathered from Apennine Mountain peaks.
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In more recent times, from the early 17th century through the beginning of the 20th century Europeans used ice in holding devices (early iceboxes) for the same purpose. Large blocks of ice were harvested all across Europe, from the polar glaciers of Norway to the frozen Lake Sylans in the Jura Mountains.
ICE HARVESTING IN EARLY AMERICA
According to Joseph Jones, Jr., in his book, Americas Icemen, the earliest reference to the United States ice industry is a patent issued in 1665 to the Governor of Virginia, Sir William Berkeley, to preserve snow and ice. Commercial harvesting of ice from ponds and lakes is now a thing of the past. However, its impact before refrigeration was immeasurable. Until the turn of the 19th century, America was content to chill its food and drink in fruit cellars and springhouses. People masked the taste of spoiled foods with spices, and fresh foods could only be safely shipped short distances.
All of that changed in 1805 when Frederick Tudor, known as the "Ice King of Boston," began shipping ice cut from a pond in Lynn, Massachusetts, to the southern cities of Charleston, Mobile, and New Orleans. By 1856, his ice empire stretched as far as Cuba, Jamaica, India, England, and South America. Tudor built a vast and prosperous network of ships, giant icehouses, and local distribution agencies.
The Cape Pond Ice Company was started as the Gloucester Ice Company in 1848 by a blacksmith named Nathaniel Webster. Recognizing the opportunity to supply ice to the fresh fish industry around Gloucester, Massachusetts, Webster dammed a local brook and built his first icehouse. After harvesting his "frozen load" with teams of men and horses, Webster would store the ice in sawdust and salt hay until it was needed in the summer months.
Axes were first used to chop ice from ponds around 1785. The ice saw soon followed, which allowed the harvester to hand saw evenly shaped blocks. Even so, this proved to be tedious and dangerous work for the harvesters. The introduction of the steam engine in 1870 helped reduce the heavy labor of sawing. This was the preferred method of harvesting until electric saws were introduced around 1912.
From 1800 to 1920 nearly every community in the northeastern United States had its local ice harvesting and storage company. People demanded something better than a steady diet of dried and salted meats. Breweries could work all year instead of only in the winter. The availability of ice was vital to meat packers, dairy farmers, and even the medical community. In 1806, the first shipment of pond-cut ice was sent from the United States to Martinique to help treat victims of yellow fever.
With the invention of the insulated railroad car in 1857, meat shipments became daily occurrences. By 1873, Chicago meat packers were sending fresh beef products to the east coast at the rate of three carloads a day. Ice was becoming even more precious. In 1860, a Chicago produce dealer observed that when salt was placed on ice, the ice melted at a lower temperature causing the formation of chilled air. This led to the invention of refrigeration machinery to make ice. The natural ice industry in the United States reached its zenith in 1886, when its annual harvest reached 25 million tons.
MAKING THE MEDIUM: THE MANUFACTURE OF ICE
When nature could not keep up with demand for high-quality, clean, pure ice, man invented the means for manufacturing ice. Ice manufacturing began in America around 1910, and the first self-contained household electric refrigerator was built in 1915. By 1925, no significant amount of natural ice was being commercially harvested.
The first commercially manufactured ice, known as plate ice, was produced in sheets measuring 20' x 10' x 1' and weighing close to 14,000 pounds. The ice was then cut into smaller blocks, known as "cakes," according to the needs of the buyer.
Presently, there are three forms of commercially, or artificially, made ice used for displays: brine tank method, circulating tank method, and molded sculpture method.
Brine Tank ("Can Ice") Method
Until recently, most manufactured ice was made in galvanized cans. In this process, pure, chilled water is placed in galvanized containers designed to produce blocks weighing from 10 to 400 lb. The filled cans are partially submerged in a brine tank filled with sodium chloride or a similar substance. The brine itself is chilled and circulated around the metal cans, slowly freezing the water inside. During the freezing process, small contaminate particles and dust are forced to the center of the block and produce a darker section of slush. The slush is decanted through a hole, and fresh water replaces the slush. After a few days of freezing, a partially opaque block is produced.
Although ice produced in this way is generally clean, the feather of air running down the blocks core leaves an undesirable "snow effect" in the center of the block and therefore in the carvings. Although not perfect, this ice is commonly accepted by many carvers. Using distilled water (free of contaminates) helps to produce clear ice, but it doesn't help to remove all of the air.
Circulating Tank Method
Another more recent method calls for agitating the water as it is being frozen to produce slick ice. Small circulating pumps, similar to those used in garden ponds, are placed in block-chilling machines at the surface level of the water. The pumps slowly move the water around as it is freezing from the bottom upwards. This process allows air, minerals, and other impurities to circulate to the top of the ice, thereby producing clear ice blocks. It generally takes 2 to 3 days to form these 300-1b. sculpting blocks, depending on the room temperature surrounding the machine. The pumps are removed just prior to harvesting and before they freeze into the block. The blocks are clear, air-free, and denser than those produced using the brine tank method. Their density causes the ice to be stronger than other ice blocks.
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Molded Sculpture Method
There are actually two methods of producing molded sculptures: rubber or plastic molds, and ice mold machines.
First, as an alternative to sculpting raw blocks into finished works of art, operators may choose to purchase rubber or plastic molds that can be filled with water and then frozen. Some types of molds, mostly those made of plastic, are not reusable because they are destroyed when removing the frozen ice figure. The water is not circulated in the mold, and the resultant sculpture can be cloudy.
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Other molds, much more costly, may be reused numerous times. These molds are made from two parts: a durable rubber liner that has the finished details of the sculpture, and a fiberglass outer case that provides the needed rigidity to the form as it freezes. Water is poured through an opening in the pattern, and then the water-filled mold is placed in a freezer for several days to harden. These molds have improved in recent years, with larger and more detailed designs available on the market.
A second style of molded ice is made in a machine specifically designed to produce molded ice. Mold forms are filled with water and submerged in a solution of propylene glycol to facilitate even freezing. After 1 or 2 days the mold, complete with a frozen ice sculpture, is removed from the solution.
Obvious advantages to the molded sculpture method are:
* Limited skill and few tools are required
* The appearance of the final product is consistent
* It is possible to produce several sculptures simultaneously, if equipment is available
* It is possible to produce the pieces around the clock However, in our opinion, the disadvantages are greater:
* There are a limited number of molds on the market, so the customer has fewer options
* All operators can offer the same product
* The molds are limited in size and scope and many only produce small, tabletop-sized pieces
* Finished pieces are often cloudy, since the water is not circulated during the freezing process
* Molds can be very expensive and require storage
* The artist gains little creative satisfaction using molds rather than developing his own sculpting talents
In the 1950s, covets used several methods to color their sculptures. After futile attempts m color ice with dyed oils or colored water pouted into the core cavity during the formation of the ice, they seeded on applying colors after the fact. One common method was to apply aerosol snow spray flakes m the finished sculpture. Individual sections, or the entire sculpture, were coated with the colored spray Another method involved carefully placing wee colored crepe paper over the finished sculpture, then spraying is with a chin film of cold water m seal the paper in place. This second method was intended solely foe outdoor use.
During the 1980s and 1990s, many ice artist experimented with making sculptures from colored ice blocks. Commercial icehouses added liquid dyes to their machines as the blocks were being made. However, dyes behave as foreign particles in freezing water, so any agitation with air causes them m pool and concentrate in various locations of the block often at the top. The result is a spottily colored block
When ice-water blocks ace agitated without air; the colors are more evenly distributed, but the finished blocks are cloudy and softer than normal. Although they can be carved, sculptors often find these blocks to be too soft to sculpt.
Another consideration is the faster melting tare of colored ice. Blocks fiat contain more air cells ace softer and melt faster. Additionally, dyed ice often stains the tablecloths and skirting around the sculpture, and can make an unsightly appearance of the buffet table on which it is displayed.
To make a block of colored ice, the sculpture needs 2 oz. of food coloring mixed with 1 pint of whole milk The colored milk is added into the water in the block chamber, and is then gently and evenly blended into the water to distribute its color The block is allowed to freeze, without the water pumps running, for 3 to 4 days. Running the pumps will cause the colorants to rise to the surface. Sniped blocks can be made by freezing single layers of colored water one upon another.
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Gels and colored lighting are highly preferred methods of accentuating and highlighting sculptures with color (see Chapters 10 and 11) and are recommended over the use of colored ice.
THE PERFECT BLOCK
The quality of a finished sculpture is greatly enhanced and affected by the quality of the ice used. Ice chat is flee of impurities, visible air traces, and large cracks greatly increases the ability of the sculptor to create a memorable work Sculptors should use only the best ice available, even if it means purchasing it from sources outside their immediate geographical area.
Care must be taken when storing the ice so as to prevent sublimation caused by the refrigeration process. In sublimation, ice changes directly to water vapor without melting. Refrigeration involves removing warm circulating air; and moisture along with it. Therefore, blocks and sculptures will literally dehydrate if not properly covered and protected from the circulating air.
Plastic bags under cardboard boxes work well to cover and insulate new ice blocks and prevent sublimation. It is better to store blocks on plastic, rubber, Ethafoam sheets, or other non-porous material, to make it easier to slide the blocks in and out of storage. Cardboard alone is absorbent and is therefore not the best material on which to rest ice.
Exposure to the elements is often unavoidable. It is important to reduce exposure to wind, rain, humidity, and sunshine as much as possible. Sunlight's ultraviolet rays cause a greenhouse effect and melt the ice from the inside. Humidity can cause thermo-shock on a cold, non-tempered block, while rain and wind will erode the ice from the outside. These elements must be considered when designing a sculpture to be displayed under various weather conditions.
Meet the Artist--Robert Schultz
Robert Schultz, Banquet Chef-Manager for Grand Rapids Community College (GRCC) in Michigan, has also been serving as an adjunct instructor for the college's Hospitality Education Department teaching courses in Introductory Ice Carving. His enthusiasm for the subject has created a growing demand for the course, filling four sections a year. Chef Schultz has led ice-sculpting seminars in Las Vegas for Michael Roman's annual CaterSource Convention and, over the years, has been very successful in coaching GRCC students in NICA-sanctioned and other ice-carving competitions. Chef Schultz is also a founding partner in Son-in-Law Products, makers of preservative free salsas, BBQ sauces and injectable marinades.
Ask the Artist
Q What kind of ice do you use in practice and in competition?
A We are fortunate that the college has had two Clinebell Ice Block Makers for over 10 years, and a graduate of our program recently donated a third. We only use slick ice for practice and in competition. Most of the time we can make enough of our own, but sometimes we still have to buy ten or twenty blocks ... but the quality is well worth it.
Q How far in advance can you make the blocks and sculptures before you see any deterioration?
A We frequently make blocks of ice up to a month before we need to use them with no trouble, as long as we leave them covered in their plastic bags. We've also purchased cardboard boxes to cover the bagged ice if we know we're going to be storing the ice for any extended length of time. We store sculptures for a few weeks; sometimes the students are working on their first sculptures over a 2- or 3-week period. Even though we have a dedicated walk-in freezer for our ice blocks and sculptures, right where we do our sculpting, we don't like to store sculptures for too long for fear of accidental breakage to their extremities. In any case by to keep them covered with plastic to slow their sublimation.
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|Title Annotation:||Part I Learning Sculpting in Ice|
|Publication:||Ice Sculpting the Modern Way|
|Date:||Jan 1, 2004|
|Previous Article:||Chapter 1 The art of sculpting.|
|Next Article:||Chapter 3 The sculptor's tools and equipment.|