Paper Making 102 Lab

North Carolina State University

Lab Manual:

Handsheet Preparation

Author:

Richard Venditti Associate Professor Department of Wood and Paper Science Raleigh NC 27695-8005 Email: [email protected]

D:\Docs\2017-07-04\003f0a8d0a66d8a5a8db92665baca8bf.doc Handsheet Preparation:

Objective: Be able to make a sheet of paper (handsheet) for use in further display or testing.

Background: The ability to make reproducible samples of paper manually from a handsheet mold is integral in the analysis of any type of papermaking process. Manually preparing handsheets is the most convenient method to study materials for papermaking suitability when the amount of material available or the amount of paper to be formed is less than 10 grams. Typical analysis of handsheets might include dirt count, brightness or color, strength properties, and other physical properties such as density or smoothness. To accurately interpret the papermaking furnish, the handsheets must be free from wrinkles, unintended thick or thin spots, and mechanical damage. Thus, it is critical to develop the handsheet making technique so that useful information can be extracted from the prepared handsheet. The following procedure describes in detail the use of handsheet making with the NCSU provided handsheet mold, see Figure.

Procedure:

1. Put 1000 ml of hot tap water in a blender. 2. Tear about 2.0 air dry grams of paper into 2 inch squares and place in the blender. Suggested papers to use are the following A. High quality toilet tissue as a model for bleached fibers. B. The outer liner of a corrugated box as a model for unbleached fibers. ** This material is the easiest for making handsheets. It is suggested that this material be used to practice and develop the technique. Once the user is comfortable with this material, then try the others. C. Newspaper as a model for a mechanical pulp. 4. Cover the blender and blend for 3 minutes. 5. Make sure the top and bottom parts of the handsheet mold and the papermachine wire are clean. If they are not, carefully rinse with cold water. A mild detergent can also be used to clean; however, make sure to rinse all of the detergent from the apparatus, residual detergent can affect the properties of the produced handsheets. 6. See figure below. Place the handsheet mold in a large tub in a sink and add water to the tub until the level of the water is about one inch above the screen. (see Experimental Figure below) 7. Pour the pulped sample into the top of the handsheet mold. Gently agitate pulp with fingertips for 3 seconds, not scraping the wire surface. 8. Lift the mold out of the water keeping it horizontal. Allow as much water to drain as possible. 9. Put the mold on a counter. 10. Open the latches of the mold, place 4 sheets of paper towels (or blotting paper if you have it) on top of the wet sheet and gently press the towels down on the sheet with your hands to remove as much water as possible. The goal is to remove as much water from the fiber mat as possible without disturbing the mat. 11. Remove all the towels except the one in contact with the sheet. Repeat step 10 if needed. 12. Gently and slowly attempt to peel the towel and the fiber mat off the wire together from an edge. Check to see if the fiber mat is ripping. If it is, try peeling from another edge. Be gentle with the fiber mat and towel. 13. (Note: there is no exact way to best dry your sheet. Depending on the thickness of your sheet, the type of towels you use and the temperature of your iron, adjustments to the below drying method may be needed. Practice and careful observation while drying is sometimes the best way to determine how best to dry.) 14. Place the towel backing on top of 2 other dry towel sheets on a hard, heat-safe surface. Place three sheets of towel on top of the fiber mat, see Figure.

D:\Docs\2017-07-04\003f0a8d0a66d8a5a8db92665baca8bf.doc 15. SAFETY: Always use caution with a laundry iron. Do not leave a hot iron where it could be incidentally contacted or dropped off a table. Make sure the electric cord is not in a position to be snagged accidentally. Make sure to turn off the iron when finished using. Place a pre-heated laundry iron (at the highest heat setting) onto the towel-paper sheet-towel sandwich. Change the position of the iron as needed to dry all areas of the sheet. 16. After about 3 minutes remove the outer towels. Try very gently to peel the top inner towel off the handsheet. The handsheet should appear to be like paper, although probably not fully dried. Try another edge of the handsheet if it seems like it is stuck. Sometimes it helps to try to pick at some of the fibers at the edges until the handsheet starts to release from the towel. Peel off the bottom towel in contact with the handsheet in a similar way. 17. Finish drying the handsheet by gently lifting and pressing the iron directly on different parts of the handsheet. This will densify and smooth the handsheet. Do not rub the handsheet surface with the iron in a horizontal motion because this may rub off fibers. Drying the handsheet should take about 3 more minutes. Check to make sure the handsheet is not burning and turning brown. 18. Labeling the handsheet on the very edge is a good practice to use. Weigh the handsheet on a scale if needed. 19. Rinse the handsheet mold, making sure the papermachine wire is especially clear of any debris. 20. Congratulations, the experiment is complete!

Schematic of the Handsheet Mold:

Large tub

Handsheet mold water level About 1-inch Wire

Schematic of the Towel-Handsheet for Drying TOP Dry Towels

Handsheet attached to tissue From handsheet mold

Dry Towels

Hard, Heat-safe Counter or Table Top

Further Experiments

D:\Docs\2017-07-04\003f0a8d0a66d8a5a8db92665baca8bf.doc 1. The freeness of a papermaking fiber furnish is a measurement that describes how rapidly the fibers release water on the papermachine. Higher freeness indicates faster water drainage. Obviously, a fiber furnish that drains water rapidly will allow the papermachine to be sped up, thereby increasing production and profitability. A simple method to determine the relative freeness of fibers is to time how long it takes water to drain from a handsheet mold with a given type of fibers. This can be done by always using the same amount of fiber, the same amount of water and using a stop watch to determine the time for the water level to drop to the papermachine screen. Try experiments in which: a. You compare toilet tissue, newsprint, copy paper, old corrugated container, etc. b. You use one type of fiber source and in separate experiments pulp for 1, 3, 6, 12, and 20 minutes. c. Combine the different types of fiber sources at different ratios and determine if the freeness versus content line is a linear relationship. For example, try copy paper and OCC at 100/0, 75/25, 50/50, 25/75, 0/100 blends.

2. Pulp different sources of recovered paper, make handsheets and test them for strength properties.

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