paper

NOTE: The powerpoint for the wood and paper parts of the lab is here. Note that it has some embedded animations and movies that will only work in the "show" or "slideshow" mode. For the flash animations, you may need to update your browser and/or download the shockwave plug-in

INTRODUCTION

Until recently with the dawn of common computer usage, paper has been the primary means of written communication for the developed world. In many nations, this is still the case. Annually, each American uses about 144 pounds of paper! This is an enormous amount, very little of which is recycled and most of which ends up in landfills. This lab will answer the questions: What is paper? What properties does it have? How is it made? What is it made of?

Objectives for this part of the lab are to:
□ outline the steps in the papermaking process
□ learn about the properties of various types of paper
□ learn about other paper-type products such as cellophane
□ study the plants used to make paper–trees, flax, hemp, kenaf, etc.
□ discuss the properties and merits of recycled paper
□ make some recycled paper

Safety concerns:
□ Papermaking is wet and messy. Wipe up any water that spills on the floor.
□ The blender is electric; we are using lots of water. Be careful mixing the two.

WHAT IS PAPER?

Not every writing surface is paper. Egyptian papyrus (Cyperus papyrus, Cyperaceae) is not paper. Neither is the "rice paper" (Fatsia papyrifera, Araliaceae) of the Orient or the "mulberry paper" (Broussonetia papyrifera, Moraceae) of the Mayans and Polynesians. Papyrus is a material formed by many strips of papyrus leaves being pressed together. The other two forms of "paper" were made by pounding various parts of the plants together, also not truly paper.

Paper is separated plant fibers that have been matted together to form a sheet. As stated by Dard Hunter (old grand master of paper making), "To be classed as true paper, the thin sheets must be made from fiber that has been macerated until each individual filament is a separate unit; the fibers are then intermixed with water, and, by the use of a sieve like screen, are lifted from the water in the form of a thin stratum, the water draining through the small openings of the screen leaving a sheet of matted fiber upon the screen's surface. This thin layer of intertwined fiber is paper." (Hand Papermaking, Inc., 1998)

THE HISTORY OF PAPER

It is generally agreed that the first paper was made in China around 100 A.D. It was made of mulberry fibers and mixed with other fibers, like hemp and flax. The key difference between this first true paper and its predecessors was that the fibers had been separated from each other prior to forming a sheet. The technique spread through the orient, to Samarkand then into the Arab and Egyptian regions by 1000 AD. By 1100 AD, the technique had reached Europe, first in Spain and then spreading to Italy then the rest of now modern Europe. Prior to the introduction of paper, parchment (prepared animal skins) had been the surface of choice for writing, but as demand for written materials increased, the supply of goat and sheep skins could not keep up. Thus, paper won the technology war.

Early on, plant fibers were separated by soaking and beating. This was a time consuming and often labor intensive process. In 1851, the first chemical methods were developed to separate fibers, especially wood fibers. This method used caustic alkali to boil wood chips in until nothing was left but a pot of fiber. In 1857 in Paris, the second chemical method was developed using sulfates. One of these two methods for separating wood fibers is used is usually used today. (The above referenced from Hand Papermaking, Inc.)

WHAT PLANT PARTS ARE USED TO MAKE PAPER?

The part needed is fiber–basically, fiber is cellulose. Plants make cellulose as a part of their cell walls and it is used for structural support. Since plants don't have bones for structural support, they secrete various compounds to form an "exoskeleton" around each cell membrane. This is known as the cell wall. The cell wall varies according to the tissue and the amount of support needed by it. Some cells have only a primary cell wall, which is thin structure, anywhere from 1 to 4 micrometers and is composed roughly of 9-25% cellulose, microfibrils, hemicelluloses (20-50%), pectin-like substances (10-35%), and proteins (10%). Primary cell walls have a high tensile strength and are porous. They are "stuck" together by the middle lamella. The middle lamella is made of pectin-like substances which are secreted by the cell between adjacent primary cell walls to "glue" them together.

If a plant cell is to function as a structural support cell or xylem tissue, a secondary cell wall is secreted. Secondary cell walls are made of about 45% cellulose, 30% hemicellulose, and 22-28% lignin. They are usually much thicker than the primary cell wall, and the combination of the different components result in wood being one of the strongest materials on earth. However, lignin doesn't exist only in the secondary cell wall. In cells with a secondary cell wall, lignin is deposited first in the middle lamella, then the primary cell wall, and finally the secondary cell wall, uniting all the factors of the cell wall complex. (Salisbury and Ross, 1992)

Lignin is much harder and more brittle than cellulose and is not a good primary component of paper. It is also very difficult to remove from cellulose. Do we want lignin or pectin in paper? The presence of these substances causes the paper to yellow and crumble as the pectin and lignin degrade. Thus, for any kind of quality paper to be made, the lignin and pectin must not be present at all or must be removed first. Herbaceous plants don't have much lignin, thus making the separation of the cellulose fibers much easier than in woody plant tissue.

THE PAPER MAKING PROCESS

Papermaking in the contemporary sense, is a science. The paper mill employs chemical engineers and many other scientists to run the facility and it is a highly regulated process. For paper made from wood, the process includes breaking the wood into small pieces, digesting away the lignin and pectin, washing and bleaching the fibers, separating them, suspending them in a slurry, floating them into a mold, then forming, pressing, and drying the paper. The Powerpoint presentation for this lab and some of the websites linked from the online lab page will give you a good idea of the process.

WHAT PLANTS CAN BE USED TO MAKE PAPER?

The answer is, any and all. All plants contain cell walls, thus all plants have cellulose. Herbaceous plants in general have fewer secondary cell walls (and so less lignin) than do woody plants. Prior to the invention of chemical processing techniques, most paper was made of hemp, linen and cotton rags-- all herbaceous plants. In modern times, wood pulp, specifically of conifer trees, is used for paper making due to its high availability. However, with the push for environmental responsibility, other options should be sought, ones that do not contribute to deforestation. The chemical processes used to make paper from trees also result in high levels of pollution (largely as a result of removing lignin and pectin), especially water pollution. If herbaceous plants were used on a large scale in modern paper manufacturing, deforestation solely for paper would no longer be a problem, the chemical output would be reduced, and an important agricultural crop would be introduced to the farmers of this country. It is true that trees are a renewable resource. However, they are renewable on a long term scale, often several decades, not the annual renewability of herbaceous plants.

One of the plants that is good for papermaking is the hemp plant (Cannabis sativa). It’s the same species as marijuana, but it is a variety with very low THC levels. Because it’s indistinguishable from “pot” hemp, it is illegal to grow in this country. However, the processed fibers are imported from Europe for making cloth and paper, and many paper hobbyists use hemp pulp. It not only is a long, strong fiber, it is also easy to grow and actually improves the soil in the farmlands.

Kenaf (Hibiscus cannabinus) is also gaining a lot of attention. This relative of okra and cotton has two types of usable fibers in its stems and can go from seed to harvest in as little as 100 to 200 days. It’s a doubly useful plant because the seeds yield an edible oil with a healthy fatty acid make-up.

RECYCLED PAPER FACTS

- more than 500,000 trees per week are used to produce the two-thirds of newspapers that are never recycled.

- every ton of paper that is recycled saves 17 trees, 7,000 gallons of water, and 4,100 kilowatts of electricity.

- producing paper from recycled fibers reduces air pollutants by as much as 74% and water pollutants by as much as 35%.

- every ton of paper recycled leaves 3.3 cubic yards of free space in landfills.

Of course, as any economist will tell you, without demand, there is no need for supply. Recycling paper and other products is a great thing, but without buying products made from recycled materials, there is no need for recycling. So do your part: recycle and buy recycled products.

ACTIVITY: Making Recycled Paper

We will make paper in lab this week. We will need:

shredded paper from on campus blender plastic tub for holding slurry pitcher sponges mold and deckle blotters muslin squares	corrugated cardboard wood boards plant press plant dryer glitter (optional) lots and lots of water stirring spoon

Soak the shredded paper for at least 24 hours. Tear the wet paper into smaller bits. Working in small batches, blend the paper with plenty of water. The longer you blend, the finer the paper will

In a large vat, place water and blended fibers. The amount will depend on the size of your vat and how thick you want your paper. A deckle is the frame with metal screening attached This is the part that the paper sheet is formed on. The mold is the frame that gives the paper sheet its shape. The mold is always on top of the deckle with the metal screen between the two. To form a sheet of paper, put the mold and deckle together, submerge them in the tub of stirred water and fiber, and lift. Once the deckle is above the water level, gently shake side to side and front to back to interlock the fibers and to ensure an even sheet of paper. Invert this on a muslin square and remove the water from the back of the deckle with a sponge. The paper will now release from the deckle. Transfer the muslin and wet paper to the plant press stacked with blotters and corrugates. Cover with another muslin (or fold a large muslin over), a blotter, and another corrugate. Tuck in a little piece of paper with your name. Repeat. Place the plant press in the drying oven in room 004 when you are finished.

QUESTIONS FOR THOUGHT, REVIEW, AND STUDY: Refer to lecture, Powerpoint, textbook, and lab and field trip notes, as well as to what you learned during the laboratory activity.

1. What can we make paper out of?

2. Describe the steps in the paper production process.

3. What is a watermark? How is it made?

4. What are lignin and pectin? How do they affect the papermaking process and the resulting paper?

5. Describe the steps for making recycled paper on a small scale.

6. What should we be working on in the field of paper production?

7. How do the herbals you saw at the Cushing library reflect the changes through time in the process of book and paper production?