The Life and Science of Percy Julian
Activities and Readings
6A (Lab Activity)

Making and Sizing Paper

Introduction

Chemists are very interested in paper manufacturing because paper is treated with all kinds of chemical substances that create different effects and that give various types of papers their special properties. In this activity, you’ll learn about one of those properties (absorbency) and what role chemistry plays in creating that property.

In this activity you will learn to make and “size” paper. What does it mean to “size” paper? It’s not what it sounds like. It doesn’t mean to make paper a certain size, for example, 8.5 x 11 inches. Instead, sizing is the process of applying a chemical substance to paper while it’s being made; the substance (also called sizing) helps prevent the paper from absorbing ink into its fibers. This way, the sizing keeps the ink on the surface of the paper where it should be. Without sizing, the paper would suck up the ink and everything would be all splotchy and unreadable. Some papers are supposed to be absorbent, like blotting paper. These papers have little or no sizing.

So, to size paper means to add sizing to paper when it’s being made. And that’s what you’ll be doing in this activity. Starch is just one example of the many chemical substances that can be used for sizing paper.

Although Percy Julian was unable to work at the Institute of Paper Chemistry in Appleton, Wisconsin, because of a town law prohibiting African Americans from spending the night in Appleton, he still ended up working on paper sizing. As director of the Soya Products Division at the Glidden Company in Chicago, he created a more effective product for sizing paper—out of soybeans.

Purpose

You will learn how to make paper in the classroom and test the effect of sizing on the paper you produce. This activity was adapted from http://www.intersurf.com/~redstic/Paper/Hand.htm.

Safety

Wear safety goggles during the entire lab. Your teacher will determine if you are to operate the food blender or processor.

Procedure

If your teacher has not prepared the paper pulp for you in advance, follow the instructions given below:

Pre-lab: Pulp Preparation

  1. Tear (do not cut) paper to be recycled into pieces the size of postage stamps.
  2. Mix the paper pieces with water. Use about 30 to 40 pieces of torn paper per 4 cups of water. The mixture may be left to soak over night.
  3. Place the paper and water mixture into a blender. Turn on blender. Regular paper takes about 30 seconds; heavier paper requires about 60 seconds. Your blended mixture of paper and water is called paper pulp.
  4. Place each batch in a tub (or large covered container if the pulp is to be stored). If the pulp has been standing for some time, stir the pulp prior using it.

Lab: Making Paper

  1. Obtain the following items from your teacher:
    • Two embroidery hoops. One hoop will have screening and the other will not. The hoop that has the screening is called a mold. The other hoop is called a deckle.
    • A plastic tub
    • Several sheets of newspaper
    • Several sheets of felt
    • Paper pulp (as made by you according to the instructions above, or by your teacher)
    • Small quantity of liquid starch (only if your teacher tells you to)
  2. Fold a sheet of newspaper into eighths (i.e., fold it in half three times). Trace the outline of the deckle on the paper and cut out the eight layers of newspaper. Keep the sheets together. You will need to repeat this step for each sheet of paper you plan to make.
  3. Trace the outline of the deckle on to a felt sheet and cut out the felt circle. Dampen and place the felt circle on top of the newspaper circles from step 2. This is your couching cushion. Repeat this step for as many sheets of paper as you will make.
  4. You or your teacher should add some pulp to your plastic tub.
  5. If you are instructed to do so by your teacher, add liquid laundry starch to your pulp. Your teacher will tell you how much to add. Stir the pulp before making your paper. Later in this activity, you will learn what effect the starch has on the paper.
  6. Place the mold and deckle together so that the screening (netting) is sandwiched between them. (See diagram.)

  7. Lower the mold and deckle vertically into the plastic tub of pulp. As you slowly pull them toward you, rotate them into a horizontal position so that you evenly scoop up some pulp across the entire mold. (See diagram.) Remember to start with the mold and deckle vertical, and end with them horizontal.
  8. Raise the mold and deckle straight up, keeping them horizontal and allowing the excess water to drain back into the tub. Gently shake the mold and deckle to distribute the pulp evenly over the screening. Remove the deckle. Do this carefully so you don't mess up the wet pulp on the mold.
  9. Cover your work area with several sheets of newspaper. Place your couching cushion on the newspaper. After the excess water is allowed to drain from the mold, hold the mold with the paper facing away from you (see diagram) and gently rotate the paper down onto the couching cushion. Press down on the far side of the mold to lift the near side away from the paper. This step may take a little practice.

  10. Once the paper has been placed on the couching cushion, place another felt circle on top of the paper. You may dry several pieces of paper on this same couching cushion as long as you separate each piece with a felt circle.
  11. Place dry newspaper on top of your couching cushion and weight the stack down with several heavy books or other weights. Allow the paper to dry. Drying the paper like this is called couching.
  12. When your paper is dry, try writing on it with a ball point pen and a felt tip marker. (Be sure the marker has a medium or fine point.)

    Results

    Compare what happens when you write on your paper in step 12 with what happens to the paper of other groups. The other groups will have used different amounts of laundry starch in their paper. What effect does the sizing (the starch) have on the writing?

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