Smoothness

 Smoothness is concerned with the surface contour of paper. It is the flatness of the surface under testing conditions which considers roughness, levelness, and compressibility. In most of the uses of paper, the character of the surface is of great importance. It is most important parameter for printer. It is common to say that paper has a "smooth" or a "rough" texture. The terms "finish" and "pattern" are frequently used in describing the contour or appearance of paper surfaces. Smoothness is important for writing, where it affects the ease of travel of the pen over the paper surface. Finish is important in bag paper as it is related to the tendency of the bag to slide when stacked. Smoothness of the paper will often determine whether or not it can be successfully printed. Smoothness also gives eye appeal as a rough paper is unattractive.

 

Smoothness (Bekk Method): This test is an indirect measure of paper smoothness when it is under moderate pressure( 100 kPa). The standards test procedure is described in TAPPI T 479.

 

Roughness (Sheffield Method): This test is an indirect measure of paper smoothness or roughness. It is a measurement of air flow between the specimen (backed by flat glass on the bottom side) and two pressurized, concentric annular lands that are impressed in to the sample from top. The standards test procedure is described in TAPPI T 538.

Roughness (Print-surf Method): Very similar to Sheffield methods. The standards test procedure is described in TAPPI T 555.

Typical Smoothness Values
Grade	Parker Print Surf (μm)	Bendtsen (mls/min)
Newsprint (40 - 49g/m2)	2.6-4.5	80-140
Stationery (45-135g/m2)	0.8-2.6	50-300
Business Papers (80g/m2)		100-300
Test Liner (186 g/m2)		1750

Temperature and Humidity: Conditioning of Paper

 

As explained above it is important to control the moisture content of paper and keep it stable during converting operation. To keep moisture content constant, it is important that paper is conditioned. Conditioning of paper is also of important in many printing and converting operations. In addition to the effect of moisture content on physical properties, it also determines the build up of static of the paper sheet subjected to pressure and to friction. The tendency for paper to develop static becomes greater with increasing dryness. Cellulose fibers are hygroscopic i.e. they are capable of absorbing water from the surrounding atmosphere. The amount of absorbed water depends on the humidity and the temperature of the air in contact with the paper. Hence, changes in temperature and humidity, even slight changes, can often affect the test results. 

So, it is necessary to maintain standard conditions of humidity and temperature for conditioning. 

Moisture

Moisture in paper varies from 2 - 12% depending on relative humidity, type of pulp used, degree of refining and chemical used. Almost all grade of paper has some percentage of moisture. Most physical properties of paper undergo change as a result of variations in moisture content. Water has the effect of plasticizing the cellulose fiber and of relaxing and weakening the inter-fiber bonding. The electrical resistance and the dielectric constant of paper both vary with moisture content. The absorption and reflectance of certain bands of infrared and microwave radiation by paper are affected by its moisture content. The amount of water present in a sheet of paper is usually expressed as a percent. The amount of water plays an important role in calendaring, printing and converting process. Moisture control is also significant to the economic aspect of paper making. Water comes free. Poor moisture control can adversely affect many paper properties.

 

The absolute moisture content is expressed as a % of the paper/paperboard weight. The sample is generally not conditioned while doing this test. The standard procedures are laid out in TAPPI T 412 and ISO 287, SCAN P4

Typical Moisture Values
Grade	%
Newsprint	7.5 - 9.5
Office/Business Paper	4 -4.5
Marketing Wood Pulp	10
Printing Paper	6 -7
Tissue	2 - 7
Accepted trade tolerance +/- 10%

MD and CD

Machine and Cross Direction on paper machine

 

In paper machine approach flow system, when stock passes through pressure screen, the fibers are oriented lengthwise. If the stock velocity from headbox slice is equal or less than wire speed, fibers which are already oriented lengthwise, will align in the direction of wire run. Fiber alignment can be altered to some extent if stock velocity is less than wire speed. So all papers have a definite grain direction due to greater orientation of fibers in the direction of paper machine run. This grain direction is known as machine direction. The cross direction is the direction of paper at right angles to the machine direction. Some of the properties vary with the MD and CD and hence the values are reported in both the directions. The sheet which have all relevant properties same or almost same in both direction are known as 'square sheet'.

 

While sheeting the paper, machine and cross direction are to be kept in mind and the sheet cutting to be done to suit the end use requirements. E.g. 1. All printing papers are to be cut in long grain (The biggest dimension in the grain direction). 2. Book papers fold better and the book stays open better if the sheets are out so that the machine direction runs up and down the pages. 3. Wrap around labels for metal cans and bottles are to be cut with the machine direction vertical to obtain greater flexibility about the can. Long grain and Short grain : The sheet is in long grain if the larger dimension is parallel to grain (MD) direction. The sheet is said to be in short grain if the larger dimension is parallel to cross direction (CD).

 

There is no sure way to determine the MD or CD of a sheet but one crude method which work is; cut a strip of about 1" wide and 2" long paper and moist it. Put this moist sheet on a smooth surface or hand. As sheet will dry it will curl. The direction of curl is CD as paper contract in CD more than MD while drying. 

Formation and friction in paper

Formation

Formation is an indicator of how uniformly the fibers and fillers are distributed in the sheet. Formation plays an important role as most of the paper properties depend on it. A paper is as strong as its weakest point. A poorly formed sheet will have more weak and thin or thick spots. These will affect properties like caliper, opacity, strength etc. Paper formation also affects the coating capabilities and printing characteristics of the paper.

           There is no standard method or unit to express formation. It is a relative or subjective evaluation.

Friction

 

Friction is the resisting force that occurs between two paper or paperboard surfaces in contact when the surfaces are brought to slide against each other. This property is measured as a coefficient of friction, which is the ratio of the frictional force, to a force acting perpendicular to the two surfaces.

 

Two components of friction can be measured, these being static and kinetic friction. Static friction is the force resisting initial motion between the surfaces and kinetic friction is the force resisting motion of the two surfaces sliding against each other when already sliding at a constant speed.

 

Measurement of the coefficient of friction has applications in packaging where a high coefficient will indicate that containers such as sacks, bags and paperboard containers will resist sliding in unit loads or on packaging lines. This property is also important in printing papers, since a specific coefficient of friction is needed so that individual sheets will slide over each other, otherwise double press feeding may result.

 

There are two methods of measuring Co-efficient of friction of paper. One, which uses Incline Plane is explained in TAPPI T 548 & T815, the second method, which uses Horizontal Plane is explained in TAPPI T 549 & T816.

Typical Co-efficient of Friction Values Using Horizontal Plane Method
Grade	Static Friction	Kinetic Friction
Office/Business Paper	0.50-0.65	0.35-0.5
Silk Coated Paper	0.45-0.55	0.30-0.45
Gloss Coated Paper	0.40-0.50	0.30-0.40

Dimensional Stability

Cellulose fibers (main constituent of paper) swell in diameter from 15 to 20% from dry condition to saturation point. Since most of the fiber in paper sheet are aligned in the machine run direction, absorption and de-absorption of moisture by paper causes the change in CD dimension. Such changes in dimension may seriously affect register in printing processes and interfere with the use of such items as tabulating cards. Uneven dimensional changes cause undesirable cockling and curling. Dimensional changes in paper originate in the swelling and contraction of the individual fibers. It is impossible to be precise about the degree of this swelling because paper-making fibers differ considerably in this property, and because the irregular cross-section of fibers creates difficulty in defining diameter. Change that occurs in the dimensions of paper with variation in the moisture content is an important consideration in the use of paper. All papers expand with increased moisture content and contract with decreased moisture content, but the rate and extent of changes vary with different papers.

 

Dimensional stability of paper can be improved by avoiding fiber to absorb moisture. Well sized papers have better dimensional stability.

For more details on Dimensional Stability, please read Dimensional Stability Notes by Chuck Green

Typical Values
Grade	MD (%)	CD (%)
Carbonless Paper	0.050-0.150	0.200-0.400
Bond Paper	0.100-0.200	0.200-0.400
Coated Art Paper (under 200 g/m2)	0.090-0.150	0.150-0.350
Gasket Paper	0.400-1.000	0.500-1.100

Juice Box

Background

 For centuries, people all over the world have been drinking fruit juice. Today, it is available in both frozen concentrate and liquid form and packaged in a variety of ways, including bottles, cans, and—most recently—boxes. A juice box is an individual-sized container that usually holds 4-32 oz (118-946 ml) of juice and generally comes with an attached straw that can be removed and inserted for drinking. A juice box is considered an aseptic container, meaning it is manufactured and filled under sterile conditions and requires no refrigeration or preservatives to remain germ-free. Along with its portability and convenience, the juice box has gained widespread popularity due to the brick-shaped container's composition of unbreakable materials and tight seal.

History

The aseptic container was invented in the 1960s by a Swedish man named Ruben Rausing. In 1963, Rausing was trying to figure out a more efficient method to get milk to the market. He needed a container that was smaller and less cumbersome than the metal canisters being used. Rausing developed a precursor to the juice box: a brick-shaped box he named the Tetra Brik. Because of their rectangular shape, Tetra Briks, when stacked on top of each other, took up half the space of the old containers. Five years later, Rausing made an even bigger breakthrough when he figured out how to fill the Tetra Briks under completely sterile, or aseptic, conditions.

Once the juice box was introduced to the United States in 1980, competitors began entering the market at a rapid rate. These companies began implementing all sorts of ideas to gain larger shares of the market, including filling the juice boxes with a variety of different flavors, adding vitamins and other nutrients, and making packaging changes to widen the juice box's appeal. By 1986, juice boxes made up approximately 20% of the United States juice market.

When juice boxes first entered the market, they were often filled with diluted juice drinks rather than real fruit juice. However, realizing that Americans were becoming more health conscious, the juice box industry responded by filling the boxes with healthier beverages. A number of companies added vitamins, such as A and C. In the early 1990s, Minute Maid became the first company to add calcium to its juice boxes. Other companies soon followed.

Environmental concerns

Despite their growing popularity, not everyone had positive things to say about juice boxes. Environmental groups were worried about the effect that juice boxes and other aseptic containers could have on the environment. Specifically, these groups were afraid that aseptic containers would fill the nation's landfills because they are not as easy to recycle as other types of packages. The state of Maine even went so far as to ban the sale aseptic containers. This ban was later repealed, but other states have considered adopting similar legislation.

In response to this opposition, the Aseptic Packaging Council (APC), a trade association that represents the major United States manufacturers of aseptic packages, was formed in 1989. Their primary mission was to inform the American public about the product benefits and environmental attributes of aseptic packaging. Since its inception, the APC as been working closely with communities nationwide to encourage the inclusion of juice boxes in recycling programs. These efforts have already proven successful in some communities. In addition to recycling efforts, juice box manufacturers argue that aseptic containers are actually friendlier to the environment than other types of containers. For one, they take up less room on trucks when being transported from factory to store, thus conserving energy by requiring fewer trips and using less fuel. The aseptic filling process itself also requires less energy than traditional canning and bottling methods. The manufacturers also point out that packaging makes up only 4% of the weight of a filled aseptic container in contrast to filled glass bottles, which are typically 30-40% packaging. This leaves less packaging to dispose of when dealing with an aseptic container.

In the late 1990s, attitudes about the environmental friendliness of the aseptic package began to change. In 1996, the aseptic carton won the Presidential Award for Sustainable Development, and the aseptic packaging industry was recognized for demonstrating environmental responsibility throughout the product life cycle. In 2001, this increased acceptance by environmental activists, combined with the industry's efforts toward incorporating new and innovative marketing ideas, continues to make the juice box the driving force behind the juice industry.

Raw Materials

Juice boxes are typically made up of six layers of paper (24%), polyethylene (70%), and aluminum foil (6%). The paper provides stiffness and strength and gives the package its brick shape. Polyethylene serves two purposes. On the inner most layer, it forms the seal that makes the package liquid tight. On the exterior, it provides a protective coating that keeps the package dry and provides a printing surface for nutritional and marketing information. The aluminum foil forms a barrier against light and oxygen, eliminating the need for refrigeration or preservatives to prevent spoilage. The straws are made of plastic and wrapped in cellophone. Multipacks contain six or more juice boxes, and are often wrapped in a cardboard sleeve that displays the name of the product and other specifications, then shrink-wrapped in plastic.

Design

Although they are available in a variety of sizes, virtually all juice boxes have the same basic design features. Each of these features was designed to serve a specific purpose. First, the rectangular, brick-shaped design was chosen for its convenience, particularly during transport. Second, the materials from which juice boxes are made were selected to keep the beverages inside safe and fresh.

The third basic design feature is the drinking mechanism. This can be either a straw affixed to the side of the package that can be removed and inserted into a preformed hole in the top, or a pull tab incorporated into the top of the package that may or may not be resealable. The type of drinking mechanism used depends on the size of the juice box and/or who will be using it. For example, juice boxes designed for small children often use a straw, while boxes with more adult appeal may use a pull tab. Boxes that contain more than one serving would typically use a resealable tab.

The Manufacturing 
Process

The aseptic packaging process is considered a major breakthrough in the beverage industry. During the process, the juice is sterilized outside the package using an extremely high temperature (195-285°F [91-1410°C]) and then cooled before being poured into the specially designed pre-sterilized juice box. This sterilization process is called flash heating and cooling because it is accomplished within a very short amount of time, usually three to 15 seconds, substantially reducing energy use and nutrient loss associated with conventional sterilization. This process is so revolutionary that it has won an award for innovation from the Institute of Food Technologies.

Creating the carton blanks

A. Filler operation and control. B. Sleeve extraction and forming. C. Base folding. D. Transfer station. E. Sterile air treatment. F. H202 injection. G. Drying zone. H. Filling station. 1. Ultrasonic top sealing. J. Paddle wheel ejector. K. Discharge conveyor.

• 1 The juice box itself is made UP of six layers of papers, polyethylene, and aluminium foil. First the raw paper, which is rolled on a mother roll, is printed with the appropriate marketing and nutritional information. Then the layers of polyethylene and aluminum are added. The layers are bonded together using special extrusion-lamination equipment.

• 2 Next, automated, high-speed machines crease and cut out several carton blanks, or sleeves, from the roll. The sleeves are now ready to be formed into cartons, sterilized, and filled in specially designed filling machines. This filling is generally performed at another location, separate from the plant that created the sleeves.

Sterilizing and filling the juice boxes

• 3 A programmable logic controller (PLC) monitors and controls the filling machine that is run by an operator. First, the pre-formed sleeves are loaded into a magazine directly from the shipping box. The sleeves are then extracted individually by suction, shaped into a rectangle, and slid onto a mandrel.
• 4 The inner layer of the sleeve, which is made of polyethylene, is thermally activated by convection heating.
• 5 As the mandrel wheel transports the sleeves to a pressing station, the sleeves are folded for bottom sealing. Then the sleeve bottoms are formed and sealed, creating a carton base with the top still open. The cartons are then transferred from the mandrel to the pocket chain where the tops are pre-folded.
• 6 Once the tops are pre-folded, the cartons enter the aseptic zone, where fresh air is sterilized by filters. Once in the aseptic zone, the cartons are sterilized with hydrogen peroxide vapor. Using compressed air, liquid hydrogen peroxide is forced through a nozzle into a heater where it is vaporized before being injected into the cartons. Sterile air is heated and blown into the cartons repeatedly to dry out the hydrogen peroxide, while a fan extracts vapors from the aseptic zone.
• 7 Once the cartons are sterilized, they are filled with the pre-sterilized product. Any foam that is produced during filling is extracted from cartons as necessary.
• 8 The tops of the filled cartons are folded and sealed ultrasonically above the product level. The ears are convection heated and folded down against the side panels. The finished cartons are then discharged from the filling machine on a conveyor belt.

Finishing touches

• 9 The next step is to add the drinking mechanism. The most common mechanism is a straw, although some companies offer alternative methods such as pull tabs. If a straw is used, it is wrapped in plastic and glued to the side of the box with a temporary adhesive that will allow the straw to later be pulled off the box, unwrapped, and inserted into a hole punched in the top of the box. The straw hole is created via laser cutting. If a pull tab is used it is added to the top of the box, also using a laser cutting process for the opening. This completes the creation of an individual juice box.
• 10 Often, several juice boxes are pack-aged together to form multipacks. The individual boxes are wrapped in a cardboard sleeve with nutritional and other information printed on it, then shrink-wrapped in plastic for shipping.

Quality Control

To ensure quality and safety standards are met, a PLC monitors and controls the operation of the filling machine during the sterilization of the liquid and the filling of the juice boxes. This controller is run by an operator from a console that complies with all United States Food and Drug Administration (FDA) reporting requirements. Hundreds of manual and automatic quality checks are preformed before, during, and after the sterilization and filling processes to ensure that the temperature of the liquid and speed of the process remain in the proper range; that the sterility, nutritional content, and flavor of the beverage is never compromised; that the boxes themselves remain intact with no leaks; and that the drinking mechanisms are properly attached.

Byproducts/Waste

Despite early skepticism from environmentalists, juice boxes and the aseptic packaging process used to fill them have proven to be highly environmentally friendly, resulting in much less waste and energy use than traditional beverage packaging methods.

Also, because of their light weight and unique brick shape design, juice boxes help save energy by taking up less space during transport than bottles or cans. In addition, aseptic packages do not require refrigeration during transport or storage, which also reduces energy use. During the aseptic filling process, the time and temperature are carefully monitored to ensure maximum energy efficiency without compromising the integrity of the product.

Recycling of used juice boxes helps reduce waste as well. In the 1990s there was an increase in the number of communities including juice boxes as part of their curbside recycling programs. Through a process called hydrapulping, the paper is separated from the polyethylene and ground into pulp to be used to produce other paper products.

A juice box has several layers of polyethylene, paper, and aluminum foil.

The Future

In the 1990s, sales of single-serve beverages such as juice boxes experienced record growth, and experts expected such growth to continue into the twenty-first century. Factors contributing to this growth include expansion of international operations by industry leaders such as Coca-Cola, Tropicana, and Pepsi-Cola; continued implementation of new flavors and marketing ideas to appeal to wider market segments; and new venues for selling the product such as health clubs and bike shops.

One factor that may hurt the juice industry is the fact that in 2001 the American Academy of Pediatrics recommended a reduction in juice consumption by children, explaining that drinking too much juice can lead to obesity and other health problems. It remains to be seen whether this recommendation will offset the many benefits that parents have experienced with juice boxes so far and the innovative ideas yet to be implemented by the juice box industry.

Where to Learn More

Periodicals

Kelly, Kristine Porney. "Bountiful Growth for Juices, Juice Drinks." Beverage Industry 86, no. 9 (September 1995): 10.

Kulma, Linda. "Junking the Juice Box Habit." U.S. News and World Report 130, no. 20(21 May 2001): 71.

Skenazy, Lenore. "Juice Boxes, Practical, Convenient, Fun." Knight-Ridder/Tribune News Service (3 November 1998): K7326.

Other

Aseptic Packaging Council Web Page. < http://www.aseptic.org >.

Combibloc, Inc. Web Page. < http://www.combi-blocks.com >.

Kathy Saporito

Read more: How juice box is made - making, history, used, aluminium, composition, product, industry, machine, History, Raw Materials, Design, The Manufacturing Process of juice box, Quality Control http://www.madehow.com/Volume-7/Juice-Box.html#ixzz1EZyCSvfy

Industrial Hemp

Background

Hemp is a distinct variety of the plant species Cannabis sativa L. that grows to a height anywhere from 4-15 ft (1.2-4.5 m) and up to 0.75 in (2 cm) in diameter. The plant consists of an inner layer called the pith surrounded by woody core fiber, which is often referred as hurds. Bast fibers form the outer layer. The primary bast fiber is attached to the core fiber by pectin—a glue-like substance. The primary fibers are used for textiles, cordage, and fine paper products. The wood-like core fiber is used for animal bedding, garden mulch, fuel, and an assortment of building materials.

Due to the similar leaf shape, hemp is frequently confused with marijuana, another cannabis plant. The major difference is their tetrahydrocannabinol (THC) content, the ingredient that produces the high when smoked. Marijuana can contain as much as 20% THC, compared to less than 1% for industrial hemp. Despite this difference, some countries are reluctant to legalize growing of hemp (especially the United States), since there is a fear this will make it more difficult to control the use of the drug. Most hemp varieties also have a hollow stalk that have a very high fiber content (35%), in contrast to marijuana varieties that usually have a solid stalk having low fiber content (15%).

Canada is one country that has legalized hemp, though with certain restrictions. The maximum allowable THC concentration is 0.3% and all hemp farmers are required to undergo a criminal-records check, as well as obtain a license from Health Canada. Despite these restrictions, hemp production has increased threefold in just a year, from 6, 175 acres (61.75 hectares) harvested in 1998 to nearly 20,000 acres (200 hectares) in 1999. Over 95% of the acres grown in 1999 in Canada were for hemp grain.

Farmers who grow hemp claim it is a great rotation crop and can be substituted for almost any harvest. It grows without requiring pesticides and is good at aerating the soil. On a per-acre basis, one estimate claims hemp nets farmers more income ($250-$300) than either corn or soybeans ($100-$200). A full crop of hemp only takes 90 days to grow, yielding four times more paper per acre, when compared over a similar 20 year period with redwood trees in the northwest United States. However, there are other varieties of trees that yield two to three times more than hemp.

Advocates of hemp claim that it can be used in 25,000 different products, from clothing to food to toiletries. Until the nineteenth century, hemp was used in 90% of ships' canvas sails, rigging, and nets (and thus it was a required crop in the American colonies). Today, hemp fiber is being used as a replacement for fiberglass in automotive components and made into cloth for window dressings, shower curtains, and upholstery. China is the world's largest producer of hemp fabric, whereas India produces the most hemp overall.

Other products made from hemp fiber include: insulation, particleboard, fiberboard, rope, twine, yarn, newsprint, cardboard, paper, horse stable bedding, and compost. Hemp bedding has been found superior to straw and other materials for horse stalls in reducing the smell of ammonia. Hemp seed is used to make methanol and heating oil, salad oil, pharmaceuticals, soaps, paint, and ink.

Currently 32 countries, including Canada, Great Britain, France, and China, allow farmers to grow industrial hemp. The current hemp market for sales and exports in North America is estimated at between $50-$ 100 million per year. Unites States imports of industrial woven fabrics made from hemp totaled $2.9 million in 1997. Import volume jumps to around $40 million when other products—such as paper, shampoo, and oil—are included. Textile uses of hemp represent 5% of hemp products produced in Canada.

History

Hemp was the first plant to be domestically cultivated around 8000 B.C. in Mesopotamia (present-day Turkey). Hemp was grown for fiber and food. It was recorded as being harvested in central Asia around 6500 B.C. Several centuries later, China started growing hemp as a crop and later used it in medicine. By 2700 B.C. , the Middle East, Africa, and most of Asia used hemp for fabric, rope, medicine, and food. Hemp was introduced to Europe 400 years later. The oldest surviving piece of paper, a 100% Chinese hemp parchment, was dated to A.D. 770.

From 1000 B.C. to the nineteenth century, hemp was the world's largest agricultural crop, where it was also used for paper and lamp oil. During this period, several well-known books, including the Bible and Alice in Wonderland, were printed on hemp paper, and several famous artists painted on hemp canvas. The first crop in North America was planted by a French botanist in Nova Scotia in 1606. Thomas Jefferson drafted the United States Declaration of Independence on hemp paper and grew hemp him-self. Two centuries later, the United States and Canada put a stop cannabis cultivation in 1937 with the Marijuana Tax Act (this put a one dollar per ounce tax on any hemp manufacturers), which was later lifted during the World War II effort.

Global production of hemp has been declining since the 1960s, from over 300,000 short tons (272,160 t) of hemp fiber and tow in 1961 to 69,000 short tons (62,597t) in 1997. China accounts for 36% of this production and 73% of grain production. This has dropped from 80,000 to 37, 000 short tons (72,576 to 33,566 t) over the same period. Around 1994, there were 23 paper mills using hemp fiber, at an estimated world production of 12,000 short tons (10,886 t) per year. Most of these mills were located in China and India for producing printing and writing paper. Others produced specialty papers, including cigarette paper. The average hemp pulp and paper mill produces around 5,000 short tons (4,536 t) per year, compared to wood pulp mills at 250,000 short tons (226,800t) per year.

However, in the last decade, the number of companies trading in and manufacturing hemp products has increased dramatically. The North America market is still in its infancy since Canada just legalized hemp production and sale in 1998. Hemp cultivation tests in the United States began a year later though it is still illegal to grow it commercially.

Raw Materials

Fiber processing uses few chemicals, if any at all. However, the fiber may be blended with other materials, such as synthetic fibers or resins as binders, depending on the final product being made. For paper making, water and chemicals (sodium hydroxide or sulfur compounds) are mixed with the fibers to remove the natural glue components.

The Manufacturing Process

Cultivation and harvesting

Hemp is an annual plant that grows from seed. It grows in a range of soils, but tends to grow best on land that produces high yields of corn. The soil must be well drained, rich in nitrogen, and non-acidic. Hemp prefers a mild climate, humid atmosphere, and a rainfall of at least 25-30 in (64-76 cm) per year. Soil temperatures must reach a minimum of 42-46°F (5.5-7.7°C) before seeds can be planted.

• 1 The crop is ready for harvesting high quality fiber when the plants begin to shed pollen, in mid-August for North America. Harvesting for seed occurs four to six weeks later. Fiber hemp is normally ready to harvest in 70-90 days after seeding. A special machine with rows of independent teeth and a chopper is used. To harvest hemp for textiles, specialized cutting equipment is required. Combines are used for harvesting

                                          An example of hemp and hemp fibers.

grain, which are modified to avoid machine parts being tangled up with bast fiber.

• 2 Once the crop is cut, the stalks are allowed to rett (removal of the pectin [binder] by natural exposure to the environment) in the field for four to six weeks—depending on the weather—to loosen the fibers. While the stalks lay in the field, most of the nutrients extracted by the plant are returned to the soil as the leaves decompose. The stalks are turned several times using a special machine for even retting and then baled with existing hay harvesting equipment. Bales are stored in dry places, including sheds, barns, or other covered storage. The moisture content of hemp stalks should not exceed 15%. When planted for fiber, yields range from 2-6 short tons (1.8-5.4t) of dry stalks per acre, or from 3-5 short tons (2.7-4.5 t) of baled hemp stalks per acre in Canada.

Grain processing

• 3 Hemp seeds must be properly cleaned and dried before storing. Extraction of oil usually takes place using a mechanical expeller press under a nitrogen atmosphere, otherwise known as mechanical cold pressing. Protection from oxygen, light, and heat is critical for producing a tasty oil with an acceptable shelf-life. Solvent extraction methods are also emerging for removing oil since they achieve higher yields. Such methods use hexan, liquid carbon dioxide, or ethanol as the solvent. Refining and deodorizing steps may be required for cosmetics manufacturers.
• 4 A dehulling step, which removes the crunchy skin from the seed using a crushing machine, may be required. Modifications to existing equipment may be required to adequately clean the seeds of hull residues.

Fiber processing

• 5 To separate the woody core from the bast fiber, a sequence of rollers (breakers) or a hammermill are used. The bast fiber is then cleaned and carded to the desired core content and fineness, sometimes followed by cutting to size and baling. After cleaning and carding, secondary steps are often required. These include matting for the production of non-woven mats and fleeces, pulping (the breakdown of fiber bundles by chemical and physical methods to produce fibers for paper making), and steam explosion, a chemical removal of the natural binders to produce a weavable fiber. Complete processing lines for fiber hemp have outputs ranging from 2-8 short tons/hour (1.8-7.2 t/hr).

Packaging

• 6 The primary fiber is pressed into a highly compressed bale, similar to other fibers like cotton, wool, and polyester. Other products, such as horse bedding, are packaged in a compressed bale.

Paper making

• 7 Bast fibers are usually used in paper, which are put into a spherical tank called a digester with water and chemicals. This mixture is heated for up to eight hours at elevated temperature and pressure until all fibers are separated from each other. Washing with excess water removes the chemicals and the extracted binding components (pectin). The clean fibers are then fed into a machine called a Hollander beater, which consists of a large tub equipped with a wheel revolving around a horizontal axis. This beating step, which lasts for up to 12 hours, cuts the fibers to the desired length and produces the required surface roughness for proper bonding. Bleaching chemicals are sometimes added during this step or to separate tanks with the fibers. The bleached pulp is then pumped to the paper machine or pressed to a dryness suitable for transportation to a paper mill at another location.

Quality Control

Hemp fibers are tested for tensile strength, fineness (fiber diameter), and the color is recorded. Moisture content is recorded during every stage of the growing and production process. The THC content of the plant is also contiguously tested to make sure that the level does not exceed the 0.3% mark. Research is still being conducted on the effects that hemp would have on the industry. Set standards are constantly being altered and changed.

Byproducts/Waste

The harvested hemp not used is burned. During fiber processing, the core fiber is saved and usually used to make paper, horse bedding, or construction materials. Most hemp producers recycle the core fiber by removing dust, then baling and packaging. The dust can be pressed into pellets used for fuel. The dirt and small chips of core are also used as a high nutrient soil additive.

The Future

Where it is legal, the hemp industry has been growing at an annual growth rate of 20%. Other potential uses are being developed. For instance, hemp meal has demonstrated it can be used as a food ingredient for aquiculture farms, specifically freshwater fish and shrimp. Even hemp beer has entered the Canadian market, though it is expected to remain a small part of beer sales. Composite materials for the building industry are also being investigated.

Using hemp as a source of food may become the largest application, since hemp seeds have much nutritional value. The seed contains essential fatty acids, protein, calcium, iron, zinc, and vitamins B, C, and E. Hemp seed can be made into oil or flour and can also be eaten whole, since it tastes similar to pine nuts or sunflower seeds.

The outlook for hemp in the United States is uncertain since it is still illegal to grow it. There are 10 states that passed legislation in 1998 to allow growing hemp for research purposes—Arkansas, California, Hawaii, Illinois, Minnesota, Montana, New Mexico, North Dakota, and Virginia—and a number of other states are considering it. However, federal law still prohibits growing industrial hemp. The Drug Enforcement Agency will have to change its mind before any market can be developed in the United States. Once that happens, hemp could become a billion dollar crop if there is enough investment and interest, prices are competitive, and high quality products can be made. Processing technology also needs to be upgraded for higher value-added products.

Where to Learn More

Books

Schreiber, Gisela.The Hemp Handbook. Munich, Germany: Wilhelm Heyne Verlag GMBH & Co. KG, 1997.

Periodicals

Adams, John. "Dope Idea: U. Minnesota Could Research Uses of Industrial Hemp." Minnesota Daily (March 30, 1999).

Anonymous. "Ag Study: Market for Hemp is Thin." Dese Moines Register (January 30, 2000).

Kane, Mari. "Hemp Industry Prepares to Grow." In Business (November/December 1999).

Katz, Helena. "Smoking Out New Hemp Markets." Marketing (November 22,1999).

Nickson, Carole. "All-purpose Hemp a Retail Find." Home Textiles Today (November 15, 1999).

Sturgeon, Jeff. "Hemp-Gooods Shop Capitalizes on Plant's Versatility." The Roanoke Times (August 8, 1999).

von Roekel, Jr., Gertjan. "Hemp Pulp and Paper Production." ATO-DLO Agrotechnology (1994).

von Steinberg, Bob. "In Canada, hemp hasn't lived up to the hype." Star Tribune (October 16, 1999).

Ward, Joe. "Hemp Advocates Assail U.S. Report."Courier-Journal (January 26, 2000).

Other

Geofrey G. Kime, President, Hempline Inc. 11157 Longwoods Rd., Delaware, Ontario, Canada, NOL lEO. (519) 652-0440. http://www.hempline.com . info@hempline.com.

North American Industrial Hemp Council, P.O. Box 259329, Madison, WI 53725-9329. (608) 258-0243. http://www.naihc.org . info@naihc.org.

Peter Dragla. A Maritime Industrial Hemp Product Marketing Study. Canadian Department of Agriculture and Marketing, 1999. http://agri.gov.ns.ca/pt/agron/hemp/hemp-masaf.htm (January 2001).

— Laurel M. Sheppard