Objective
The primary objective of this thesis is to increase the strength properties of currency paper by:
(1) Varying the ratio of first cut cotton linters to flax fibers in a currency furnish. Wet and dry strength additives were included in the furnishes developed.
(2) Addition of spruce fibers to the base currency furnish of 75% cotton linters, 25% flax, a wet strength additive, and a dry strength additive.
This project was an attempt to improve the strength of a base currency furnish, developed similar to the base currency furnish used by the U.S. Bureau of Printing and Engraving

Schultz, Michael D.

English

ScholarWorks at WMU

Western Michigan University ScholarWorks at WMU Paper Engineering Senior Theses Chemical and Paper Engineering 1994 Improvement of Strength Properties for Currency Paper Michael D. Schultz Western Michigan University Follow this and additional works at: https://scholarworks.wmich.edu/engineer-senior-theses  Part of the Wood Science and Pulp, Paper Technology Commons Recommended Citation Schultz, Michael D., "Improvement of Strength Properties for Currency Paper" (1994). Paper Engineering Senior Theses. 469. https://scholarworks.wmich.edu/engineer-senior-theses/469 This Dissertation/Thesis is brought to you for free and open access by the Chemical and Paper Engineering at ScholarWorks at WMU. It has been accepted for inclusion in Paper Engineering Senior Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact maira.bundza@wmich.edu. IMPROVEMENT OF STRENGTH PROPERTIES FOR CURRENCY PAPER by Michael D. Schultz Advisor: Dr. Ellsworth Shriver A thesis submitted in partial fulfillment of the course requirements for the Bachelor of Science in Engineering Degree Department of Paper and Printing Science and Engineering • Western Michigan University Kalamazoo, Michigan Table of Contents I. AcknowledgementsII. ObjectiveIII. Background InformationIV. Raw MaterialsV. Experimental ProcedureA. Phase 1B. Phase 2C. Phase 3VI. Data / ResultsVII. Discussion of ResultsVIII. ConclusionsIX. Recommendations.X. ReferencesXI. AppendicesAcknowledgements I would like to thank Dr. Ellsworth Shriver, first for helping me find a topic which interests me and secondly, for his guidance as I approached each step in my thesis development process. I would also like to thank Alpha Cellulose Corporation, P.H. Glatfelter - Ecusta Division, and Hercules Incorporated for donating materials to my thesis, as well as informing me of the characteristics and use of their products. Objective The primary objective of this thesis is to increase the strength properties of currency paper by: (1) Varying the ratio of first cut cotton !inters to flaxfibers in a currency furnish. Wet and dry strengthadditives were included in the furnishes developed.(2) Addition of spruce fibers to the base currency furnish of75% cotton !inters, 25% flax, a wet strength additive, and adry strength additive.This project was an attempt to improve the strength of a base currency furnish, developed similar to the base currency furnish used by the U.S. Bureau of Printing and Engraving. Background Information This thesis is a continuation of a Barbara A. Ness' thesis, entitled Use of Manila Hemp Fibers in Currency Paper. Ms. Ness is a 1993 Paper Science graduate of Western Michigan University. Her thesis showed that as hemp fiber was added to a base furnish of 75% cotton and 25% flax, strength properties improved. In 1988, the average life of a dollar bill in circulation, was estimated to be eighteen months. At the present time, this estimate has been decreased to only nine months1 •Financial institutions occasionally receive torn, mutilated paper currency. This currency is turned over to the U.S. Government to be destroyed, usually by shredding. The removal of these bills from circulation causes a decrease in the overall supply. In order to keep the supply constant, the U.S. Government must have new currency created. This new currency is expensive to due its specific ingredients as well as its requirements to inhibit counterfeiting. If an improved, stronger paper currency can be developed, it may be possible to extend the life of a bill, thus, reducing the need for creating new bills each year. In this project, three types of fibers were used: first-cut cotton linters, flax and spruce. Cotton linters have an average length of 5 to 7 millimeters. cotton linters are the fine hairs that remain on the cotton seed after the staple cotton has been removed. First-cut linters are linters shaved off with the first pass of a circular saw. Flax is the longest fibers used in the experiments. It averages 28 to 39 millimeters in length. These fibers are used primarily for their strength characteristics in relation to fold2 • A bill may be folded hundreds of thousands of times in its life. A greater fold strength will allow the bill to withstand a greater folding abuse. Spruce fibers are softwood fibers having an average length of 3. 5 millimeters. This fiber was chosen for its flexibility, coarseness (18 mg/lOOm), as well as its high tensile index (60 kNm/kg). Since spruce is quite flexible, it should be able to take the abuse caused by excessive folding, thus, achieving higher strength values3 • The following literature was obtained for analysis of experimental results: o U.S. Government paper currency specifications from theU.S. Treasury Department, Bureau of Engraving and Printinglocated in Washington, D.C.o Thesis entitled Use of Manila Hemp Fibers in Currency Paperby Barbara A. Ness (April 1993).Base Currency Furnish At the present time, currency paper is made by the Bureau of Engraving and Printing from a furnish consisting of the following: o cotton fiberso flax fiberso wet strength resino surface sizingThe Base Currency Furnish used in the experiments consisted of the following: o 75% First Cut Cotton Linterso 25% Flax Fiberso Wet Strength Additive (Kymene 450)o Dry Strength Additive (Carboxymethylcellulose; CMC)Experimental values from this thesis were compared to the standards used by the U. S. Government as wel 1 as the results obtained by Barbara A. Ness thesis involving hemp fibers. Guidelines of the experiments followed a similar pattern to Ms. Ness' thesis in order to further compare experimental values obtained. Raw Materials The following materials were incorporated into the various experiments, all of which have been donated by their respective manufacturer: Fibers o First-cut Cotton Linter (Alpha Cellulose Corporation)o Flax fiber (P.H. Glatfelter)o Spruce (James River)Chemical Additives o Wet Strength Additive (Kymene 450, Hercules Incorporated);added 0.5% dry basiso Dry Strength Additive (Sodium Carboxymethylcellulose, CMC -Hercules Incorporated); added 1% dry basisExperimental Procedure Phase 1 : Preliminary Experiments Phase I involved performing preliminary experiments prior to the main experiments to determine the optimum refining time for each of the three fibers. Individual beater runs were conducted for each fiber using the Valley beater. Samples were taken from the beater at various time intervals. Handsheets of each sample were made using the British Handsheet machine. After conditioning, the samples were tested for grammage, wet tensile strength, and fold strength according to TAPPI Standards (See Appendix 1). Using the data obtained, beater curves were constructed to determine the optimum beating time for the individual fibers. This optimum beating time indicated the time at which the individual fibers had the highest strength values. Phase 2: Cotton / Flax Experiment Phase two involved the development of three furnishes consisting of cotton, flax, wet strength and dry strength additives. The cotton and flax fibers were separately refined with the Valley Beater to their optimum refining time determined in Phase 1. The fibers were combined, in addition to wet and dry strength additives, to form the base experimental furnish as well as furnishes consisting of different combinations of cotton and flax fiber content. Wet strength additive (Kymene 450) was added at O. 5% dry basis, while the dry strength additive (Carboxymethylcellulose -CMC) was added at 1% dry basis.The three furnishes consisted of the following ratios ofcotton and flax fibers. Furnish A made up the experimental base furnish, while Furnishes B and C included changes in the amount of each of the fibers present. Furnish A 75% Cotton 25% Flax Furnish B 50% Cotton 50% Flax Furnish C 25% Cotton 75% Flax Handsheets were made using each furnish. As specified by the Bureau of Engraving and Printing, the basis weight of the handsheets was to fall within 84.2 - 93.0 g/m2 • All handsheets formed fell within this range, often lying in the upper half of the range specified. Testing of the handsheets took place after two days of conditioning in the testing lab at standardized conditions. Tests included grammage, wet tensile, fold endurance, burst strength, and tear strength (See Data/Results). standard deviations werecalculated for each strength tests value. Phase 3: Spruce Experiment Phase three involved the development of three furnishes consisting of cotton, flax, and spruce fibers. Wet and dry strength additives were also used at their respective amounts. Each of the three fibers were refined separately with the Valley Beater to their optimum refining time determined in Phase 1. The fibers were then combined, in addition to the wet and dry strength additives, to form three furnishes. Each furnish was composed of the Base Furnish (75% cotton and 25% flax). Added to this were various amounts of spruce fibers. The three furnishes were created using the following percentages. Furnish D 90 % Base Furnish 10% Spruce Furnish E 80 % Base Furnish 20% Spruce Furnish F 70 % Base Furnish 30% Spruce Handsheets were made using each furnish. The same target range used for the handsheets in Phase 2 was used for forming of the handsheets involving the Base Furnish and spruce fibers (84.2 -93.0 g/m2). Testing of these handsheet took place after two days of conditioning in the testing lab. Tests included grammage, wet tensile, fold endurance, burst strength, and tear strength (See Data/Results). Data / Results PHASE 1: Preliminary Experiment COTTON DATA WET WET FOLD TIME FREENESS CONSISTENCY TENSILE TENSILE (double (min) (%) (kN/m) INDEX folds) (Nm/g) 5 386 0.31 0.12 0.923 68 15 295 0.29 0.29 2.23 218 30 184 0.34 0.37 2.84 440 45 86 0.35 0.47 3.62 487 60 30 0.32 0.39 2.99 451 FLAX DATA WET WET FOLD TIME FREENESS CONSISTENCY TENSILE TENSILE (double (min) (%) (kN/m) INDEX folds) (Nm/g) 15 500 0.31 0.49 3.77 672 30 220 0.27 0.59 4.55 780 60 168 0.34 0.76 5.89 1056 90 121 0.36 0.74 5.71 957 120 86 0.29 0.68 5.23 882 SPRUCE DATA WET WET FOLD TIME FREENESS CONSISTENCY TENSILE TENSILE (double (min) ( % ) (kN/m) INDEX folds) (Nm/ g) 15 327 0.32 0.31 2.38 421 30 239 0.34 0.37 2.85 592 45 118 0.35 0.42 3.23 762 60 49 0.31 0.57 4.38 861 90 37 0.36 0.51 3.92 778 COTTON Time vs. Wet Tensile Index Wet Tensile Index (Nm/g) 5 15 30 45 60 Time (min) COTTON Time vs. Fold Fold (double folds) 600 500 400 200 100 5 15 30 45 60 Time (min) FLAX Time vs. Wet Tensile Index Wet Tensile Index (Nm/g) 15 30 60 90 120 Time (min) FLAX Time vs. Fold Fold (double folds) 1,200 1,000 800 600 400 200 15 30 60 90 120 Time (min) SPRUCE Time vs. Wet Tensile Index Wet Tensile Index (Nm/g) 15 30 45 60 90 Time (min) SPRUCE Time vs. Fold Fold (double folds) 1,000 800 600 400 200 15 30 45 60 90 Time (min) PHASE 2: COTTON/FLAX 75 I 25 50 I 50 25 I 75 PHASE 3: BASE FURNISH/ SPRUCE 90 I 10 80 I 20 70 I 30 Cotton/ Flax Data WET TENSILE FOLD BURST INDEX INDEX (double (kPam2/g) (Nm/ g) folds) 7.04 2250 3.97 8.98 2933 4.42 9.23 3640 5.89 Spruce Experiment WET TENSILE FOLD BURST INDEX INDEX (double (kPam2 /g) (Nm/ g) folds) 7.86 2360 3.86 9.22 2720 4.41 8.29 2486 4.27 TEAR INDEX (mNm2 / g) 4.11 4.86 5.63 TEAR INDEX (mNm2 / g) 4.21 4.88 4.13 WET TENSILE INDEX Cotton I Flax 10 8 6 2 Nm/g 75% / 25% 50% / 50% 25% / 75% Pulp Batch FOLD Cotton I Flax Double Folds 75% / 25% 50% / 50% 25% / 75% Pulp Batch BURST INDEX Cotton / Flax kPam � 2/g ::::::::r.:::::::::::::::::::: 3 \\�!�i\i\\\!\\\!!!!!\\lll111 : : : : :: :: : : : : : : : :: ::: :� ::: : : : : : i!!i!iiiiiiiiiiii�iiiiiiiiiii 75% / 25% 50% / 50% 25% / 75% Pulp Batch TEAR INDEX Cotton I Flax mNm � 2/g 75% / 25% 50% / 50% 25% / 75% Pulp Batch WET TENSILE INDEX Base Furnish / Spruce Nm/g .. ,:::::11111::lllllllliilliilll ◄o .. ,,•::::,,::,,,,,,,,,,,,"""""I )/\IIill\/\/I!U.} :::::::::::::::::::::::::::::z:::::: :::::::::::::::::::::::::::.:::::::::: :::::•:::::::::::::::::,::••:::::::•!••••,••= ::::::::::::::::::::;;.::::::::::::::: :::::::::::::::::z:::::::::::::::::: ::::::::::::::z:::::::::::::::::::=· :::::::::::z::::::::::::::::::::· a !l�l�l�llllllilllllllliiill'llll11111111\\1l11111ll\llll\i :::::::::::::::::::::::::::-::: :::::::::::::::::::::::z::::: ::::::::::::::::::::z:::::::: :::::::::::::::::;;.::::::::::: ::::::::::::::z:::::::::::::: :::::::::::;;,::::::::::::::::: :::::::::.-::::::::::::::::::::: s 1:�1�lllllllliii:i:111IIIIII 11111111111\l\\jjjjjjjjjjj\j[l ::::::::::::::::::::::::::z:: :::::::::::::::::::::::z::::: ::::::::::::::::::::;;.:::::::: :::::::::::::::::;;.::::::::::: ::::::::::::::;;.:::::::::::::: ::::::::::::.t::::::::::::::::: :::::::::.c:::::::::::::::::::: 4 1 l�l�lill:lllllillllllllllll iiiiiiiiii!iiiiiii\1\\111!\!ii :::::::::::::::::::::::::::.i:: ::::::::::::::::::::::::.i::::: :::::::::::::::::::::.i:::::::: ::::::::::::::::::.i::::::::::: :::::::::::::::.i:::::::::::::: ::::::::::::..<::::::::::::::::: :::::::::.i:::::::::::::::::::: 2 J:�:�: 1ll!lll!lllllliil:11:: 1111111111111111111:::::::::,, 90% I 10% 80% / 20% 70% / 30% Pulp Batch FOLD Base Furnish / Spruce 3,000 2,500 1,500 1,000 500 Double Folds 90% I 10% 80% / 20% 70% / 30% Pulp Batch BURST INDEX Base Furnish / Spruce kPam �2/g 90% I 10% 80% / 20% 70% / 30% Pulp Batch TEAR INDEX Base Furnish / Spruce 90% I 10% 80% / 20% 70% / 30% Pulp Batch Discussion of Results Phase 1: Preliminary Experiments Beater curves were obtained after testing handsheets of each fiber for wet tensile and fold strength. From the curves it was found that cotton achieved optimum strength after refining in the Valley beater for 45 minutes. The flax fibers, as well as the spruce fibers, achieved optimum strength after each was refined for 60 minutes. Phase 2; Cotton / Flax Experiment Once the optimum refining time for each fiber was obtained, the experimental furnishes of cotton and flax could be created. The furnishes consisted of combinations of each pulp after each was individually refined to its optimum strength. Tests were taken on the handsheets made including wet tensile, fold, burst strength, and tear strength. It was determined that as the amount of flax increased, the strength properties also increased. By decreasing the amount of cotton and increasing the amount of flax, a substantial increase in strength was found in relation to the base experimental furnish of 75% cotton and 25% flax. The ratio of 25% cotton and 75% flax fibers showed the highest strength values. These values were comparable to the Bureau of Engraving and Printing specifications. In addition, these values were compared with the optimum strength furnish created in a previous study. This furnish consisted of 80% Base Furnish (75% cotton / 25% flax) and 20% Hemp fibers. It was found that the ratio of 25% cotton and 75% flax had lower wet tensile values, however, achieved a greater fold strength. Wet tensile and fold were the only tests which could be compared due to the fact that no burst or tear strength values were available from the previous study. Phase 3: Spruce Experiment After refining the cotton, flax, and spruce to their respective optimum refining times for maximum strength of each fiber, the experimental furnishes were created. Tests were taken on the handsheets made from each of the three furnishes. These test included wet tensile, fold, burst, and tear strength. It was determined that as the amount of spruce fiber increased compared to the Base Furnish (75% cotton/ 25% flax), the strength properties also increased to a certain extent. The ratio of 80% Base Furnish and 2 0% spruce fiber showed the highest strength values. The addition of only 10% spruce showed an increase in strength compared to the base currency furnish of only cotton and flax fibers. Curves showed that as the spruce content reached 30%, strength declined for all tests taken. This could be due to the increase in smaller fibers compared to the lower addition of flax fibers which are considerably longer. The spruce addition level of 20% achieved strength properties comparable to that of the Bureau of Engraving and Printing. In addition, when compared to the previous study with an 80% base furnish and 20% hemp fiber addition, it was found that the 20% spruce level achieved lower wet tensile values and similar fold strength values. Conclusions o By increasing the flax fiber content while decreasing thecotton fiber content, the paper strength propertiesincreased.o Maximum strength properties of the cotton/flax furnishes wasachieved at 25% cotton linters and 75% flax fibers.o Addition of spruce fibers to a currency paper furnishincreased the strength properties.o Maximum strength properties were achieved after addition ofspruce fiber at a 20% level.Recommendations 1. Further work could be done to determine the exact length ofeach type of fiber, for which strength is optimum. Once the optimum lengths have been achieved, experiments could be conducted to re-create the furnishes discussed in this project to determine if greater strength values can be obtained. 2. Use of other fibers, such as eucalyptus, in replacement ofthe spruce used in Phase 3 of the Experimental section.3. Use of the distinctive red and blue fibers used by the Bureauof Engraving and Printing in the furnishes discussed.References 1. Bureau of Engraving and Printing Specifications, July 7,1987.2. Ness, Barbara A., "Use of Manila Hemp ·Fibers in CurrencyPaper", April 1993.3. Janes, R.L., "Fiber Characteristics", TAPP! Journal,originally presented at the 1988 TAPP! Stock PreparationShort Course, April 13-15.Appendix 1 • • TAPPI STANDARDS • Property TAPP! Standard Laboratory Processing of Pulp T 200 om-85 (Beater Method) Forming Handsheets For Physical T 205 om-88 Tests of Pulp Freeness of Pulp T 227 om-92 Physical Testing of Pulp T 220 om-88 Handsheets Consistency (concentration) of T 240 om-88 Pulp Suspensions Standard Conditioning and Testing T 402 om-88 Atmospheres for Paper, Board, Pulp Handsheets, and Related Products Wet Tensile Strength of Paper T 456 om-87 Folding Endurance of Paper T 511 om-88 (MIT Tester) Burst strength of Paper T 403 om-85 Internal Tearing Resistance of T 414 om-88 Paper (Elmendorf-type Method) Grammage of Paper and Paperboard T 410 om-88 

Improvement of Strength Properties for Currency Paper

Western Michigan University 
ScholarWorks at WMU 
Paper Engineering Senior Theses Chemical and Paper Engineering 
1994 
Improvement of Strength Properties for Currency Paper 
Michael D. Schultz 
Western Michigan University 
Follow this and additional works at: https://scholarworks.wmich.edu/engineer-senior-theses 
 Part of the Wood Science and Pulp, Paper Technology Commons 
Recommended Citation 
Schultz, Michael D., "Improvement of Strength Properties for Currency Paper" (1994). Paper Engineering 
Senior Theses. 469. 
https://scholarworks.wmich.edu/engineer-senior-theses/469 
This Dissertation/Thesis is brought to you for free and 
open access by the Chemical and Paper Engineering at 
ScholarWorks at WMU. It has been accepted for inclusion 
in Paper Engineering Senior Theses by an authorized 
administrator of ScholarWorks at WMU. For more 
information, please contact wmu-
scholarworks@wmich.edu. 
IMPROVEMENT OF STRENGTH 
PROPERTIES FOR CURRENCY PAPER 
by 
Michael D. Schultz 
Advisor: Dr. Ellsworth Shriver 
A thesis submitted in partial fulfillment 
of the course requirements for the 
Bachelor of Science in Engineering Degree 
Department of Paper and Printing 
Science and Engineering • 
Western Michigan University 
Kalamazoo, Michigan 
Table of Contents 
I. Acknowledgements
II. Objective
III. Background Information
IV. Raw Materials
V. Experimental Procedure
A. Phase 1
B. Phase 2
C. Phase 3
VI. Data / Results
VII. Discussion of Results
VIII. Conclusions
IX. Recommendations.
X. References
XI. Appendices
Acknowledgements 
I would like to thank Dr. Ellsworth Shriver, first for helping 
me find a topic which interests me and secondly, for his guidance 
as I approached each step in my thesis development process. 
I would also like to thank Alpha Cellulose Corporation, P.H. 
Glatfelter - Ecusta Division, and Hercules Incorporated for 
donating materials to my thesis, as well as informing me of the 
characteristics and use of their products. 
Objective 
The primary objective of this thesis is to increase the 
strength properties of currency paper by: 
(1) Varying the ratio of first cut cotton !inters to flax
fibers in a currency furnish. Wet and dry strength
additives were included in the furnishes developed.
(2) Addition of spruce fibers to the base currency furnish of
75% cotton !inters, 25% flax, a wet strength additive, and a
dry strength additive.
This project was an attempt to improve the strength of a base 
currency furnish, developed similar to the base currency furnish 
used by the U.S. Bureau of Printing and Engraving. 
Background Information 
This thesis is a continuation of a Barbara A. Ness' thesis, 
entitled Use of Manila Hemp Fibers in Currency Paper. Ms. Ness is 
a 1993 Paper Science graduate of Western Michigan University. 
Her thesis showed that as hemp fiber was added to a base furnish of 
75% cotton and 25% flax, strength properties improved. 
In 1988, the average life of a dollar bill in circulation, was 
estimated to be eighteen months. At the present time, this 
estimate has been decreased to only nine months1 •
Financial institutions occasionally receive torn, mutilated 
paper currency. This currency is turned over to the U.S. 
Government to be destroyed, usually by shredding. The removal of 
these bills from circulation causes a decrease in the overall 
supply. In order to keep the supply constant, the U.S. Government 
must have new currency created. This new currency is expensive to 
due its specific ingredients as well as its requirements to inhibit 
counterfeiting. If an improved, stronger paper currency can be 
developed, it may be possible to extend the life of a bill, thus, 
reducing the need for creating new bills each year. 
In this project, three types of fibers were used: first-cut 
cotton linters, flax and spruce. Cotton linters have an average 
length of 5 to 7 millimeters. cotton linters are the fine hairs 
that remain on the cotton seed after the staple cotton has been 
removed. First-cut linters are linters shaved off with the first 
pass of a circular saw. 
Flax is the longest fibers used in the experiments. It 
averages 28 to 39 millimeters in length. These fibers are used 
primarily for their strength characteristics in relation to fold2 • 
A bill may be folded hundreds of thousands of times in its life. 
A greater fold strength will allow the bill to withstand a greater 
folding abuse. 
Spruce fibers are softwood fibers having an average length of 
3. 5 millimeters. This fiber was chosen for its flexibility, 
coarseness (18 mg/lOOm), as well as its high tensile index (60 
kNm/kg). Since spruce is quite flexible, it should be able to take 
the abuse caused by excessive folding, thus, achieving higher 
strength values3 • 
The following literature was obtained for analysis of 
experimental results: 
o U.S. Government paper currency specifications from the
U.S. Treasury Department, Bureau of Engraving and Printing
located in Washington, D.C.
o Thesis entitled Use of Manila Hemp Fibers in Currency Paper
by Barbara A. Ness (April 1993).
Base Currency Furnish 
At the present time, currency paper is made by the Bureau of 
Engraving and Printing from a furnish consisting of the following: 
o cotton fibers
o flax fibers
o wet strength resin
o surface sizing
The Base Currency Furnish used in the experiments consisted of the 
following: 
o 75% First Cut Cotton Linters
o 25% Flax Fibers
o Wet Strength Additive (Kymene 450)
o Dry Strength Additive (Carboxymethylcellulose; CMC)
Experimental values from this thesis were compared to the 
standards used by the U. S. Government as wel 1 as the results 
obtained by Barbara A. Ness thesis involving hemp fibers. 
Guidelines of the experiments followed a similar pattern to Ms. 
Ness' thesis in order to further compare experimental values 
obtained. 
Raw Materials 
The following materials were incorporated into the various 
experiments, all of which have been donated by their respective 
manufacturer: 
Fibers 
o First-cut Cotton Linter (Alpha Cellulose Corporation)
o Flax fiber (P.H. Glatfelter)
o Spruce (James River)
Chemical Additives 
o Wet Strength Additive (Kymene 450, Hercules Incorporated);
added 0.5% dry basis
o Dry Strength Additive (Sodium Carboxymethylcellulose, CMC -
Hercules Incorporated); added 1% dry basis
Experimental Procedure 
Phase 1 : Preliminary Experiments 
Phase I involved performing preliminary experiments prior to 
the main experiments to determine the optimum refining time for 
each of the three fibers. 
Individual beater runs were conducted for each fiber using the 
Valley beater. Samples were taken from the beater at various time 
intervals. Handsheets of each sample were made using the British 
Handsheet machine. After conditioning, the samples were tested for 
grammage, wet tensile strength, and fold strength according to 
TAPPI Standards (See Appendix 1). 
Using the data obtained, beater curves were constructed to 
determine the optimum beating time for the individual fibers. This 
optimum beating time indicated the time at which the individual 
fibers had the highest strength values. 
Phase 2: Cotton / Flax Experiment 
Phase two involved the development of three furnishes 
consisting of cotton, flax, wet strength and dry strength 
additives. 
The cotton and flax fibers were separately refined with the 
Valley Beater to their optimum refining time determined in Phase 1. 
The fibers were combined, in addition to wet and dry strength 
additives, to form the base experimental furnish as well as 
furnishes consisting of different combinations of cotton and flax 
fiber content. 
Wet strength additive (Kymene 450) was added at O. 5% dry 
basis, while the dry strength additive (Carboxymethylcellulose -
CMC) was added at 1% dry basis.
The three furnishes consisted of the following ratios of
cotton and flax fibers. Furnish A made up the experimental base 
furnish, while Furnishes B and C included changes in the amount 
of each of the fibers present. 
Furnish A 
75% Cotton 
25% Flax 
Furnish B 
50% Cotton 
50% Flax 
Furnish C 
25% Cotton 
75% Flax 
Handsheets were made using each furnish. As specified by the 
Bureau of Engraving and Printing, the basis weight of the 
handsheets was to fall within 84.2 - 93.0 g/m2 • All handsheets 
formed fell within this range, often lying in the upper half of the 
range specified. 
Testing of the handsheets took place after two days of 
conditioning in the testing lab at standardized conditions. Tests 
included grammage, wet tensile, fold endurance, burst strength, and 
tear strength (See Data/Results). standard deviations were
calculated for each strength tests value. 
Phase 3: Spruce Experiment 
Phase three involved the development of three furnishes 
consisting of cotton, flax, and spruce fibers. Wet and dry 
strength additives were also used at their respective amounts. 
Each of the three fibers were refined separately with the 
Valley Beater to their optimum refining time determined in Phase 1. 
The fibers were then combined, in addition to the wet and dry 
strength additives, to form three furnishes. Each furnish was 
composed of the Base Furnish (75% cotton and 25% flax). Added to 
this were various amounts of spruce fibers. The three furnishes 
were created using the following percentages. 
Furnish D 
90 % Base Furnish 
10% Spruce 
Furnish E 
80 % Base Furnish 
20% Spruce 
Furnish F 
70 % Base Furnish 
30% Spruce 
Handsheets were made using each furnish. The same target 
range used for the handsheets in Phase 2 was used for forming of 
the handsheets involving the Base Furnish and spruce fibers (84.2 -
93.0 g/m2). Testing of these handsheet took place after two days 
of conditioning in the testing lab. Tests included grammage, wet 
tensile, fold endurance, burst strength, and tear strength (See 
Data/Results). 
Data / Results 
PHASE 1: Preliminary Experiment 
COTTON DATA 
WET WET FOLD 
TIME FREENESS CONSISTENCY TENSILE TENSILE (double 
(min) (%) (kN/m) INDEX folds) 
(Nm/g) 
5 386 0.31 0.12 0.923 68 
15 295 0.29 0.29 2.23 218 
30 184 0.34 0.37 2.84 440 
45 86 0.35 0.47 3.62 487 
60 30 0.32 0.39 2.99 451 
FLAX DATA 
WET WET FOLD 
TIME FREENESS CONSISTENCY TENSILE TENSILE (double 
(min) (%) (kN/m) INDEX folds) 
(Nm/g) 
15 500 0.31 0.49 3.77 672 
30 220 0.27 0.59 4.55 780 
60 168 0.34 0.76 5.89 1056 
90 121 0.36 0.74 5.71 957 
120 86 0.29 0.68 5.23 882 
SPRUCE DATA 
WET WET FOLD 
TIME FREENESS CONSISTENCY TENSILE TENSILE (double 
(min) ( % ) (kN/m) INDEX folds) 
(Nm/ g) 
15 327 0.32 0.31 2.38 421 
30 239 0.34 0.37 2.85 592 
45 118 0.35 0.42 3.23 762 
60 49 0.31 0.57 4.38 861 
90 37 0.36 0.51 3.92 778 
COTTON 
Time vs. Wet Tensile Index 
Wet Tensile Index (Nm/g) 
5 15 30 45 60 
Time (min) 
COTTON 
Time vs. Fold 
Fold (double folds) 
600 
500 
400 
200 
100 
5 15 30 45 60 
Time (min) 
FLAX 
Time vs. Wet Tensile Index 
Wet Tensile Index (Nm/g) 
15 30 60 90 120 
Time (min) 
FLAX 
Time vs. Fold 
Fold (double folds) 
1,200 
1,000 
800 
600 
400 
200 
15 30 60 90 120 
Time (min) 
SPRUCE 
Time vs. Wet Tensile Index 
Wet Tensile Index (Nm/g) 
15 30 45 60 90 
Time (min) 
SPRUCE 
Time vs. Fold 
Fold (double folds) 
1,000 
800 
600 
400 
200 
15 30 45 60 90 
Time (min) 
PHASE 2: 
COTTON/FLAX 
75 I 25 
50 I 50 
25 I 75 
PHASE 3: 
BASE 
FURNISH/ 
SPRUCE 
90 I 10 
80 I 20 
70 I 30 
Cotton/ Flax Data 
WET TENSILE FOLD BURST INDEX 
INDEX (double (kPam2/g) 
(Nm/ g) folds) 
7.04 2250 3.97 
8.98 2933 4.42 
9.23 3640 5.89 
Spruce Experiment 
WET TENSILE FOLD BURST INDEX 
INDEX (double (kPam2 /g) 
(Nm/ g) folds) 
7.86 2360 3.86 
9.22 2720 4.41 
8.29 2486 4.27 
TEAR 
INDEX 
(mNm2 / g) 
4.11 
4.86 
5.63 
TEAR 
INDEX 
(mNm2 / g) 
4.21 
4.88 
4.13 
WET TENSILE INDEX 
Cotton I Flax 
10 
8 
6 
2 
Nm/g 
75% / 25% 50% / 50% 25% / 75% 
Pulp Batch 
FOLD 
Cotton I Flax 
Double Folds 
75% / 25% 50% / 50% 25% / 75% 
Pulp Batch 
BURST INDEX 
Cotton / Flax 
kPam � 2/g 
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Pulp Batch 
TEAR INDEX 
Cotton I Flax 
mNm � 2/g 
75% / 25% 50% / 50% 25% / 75% 
Pulp Batch 
WET TENSILE INDEX 
Base Furnish / Spruce 
Nm/g 
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90% I 10% 80% / 20% 70% / 30% 
Pulp Batch 
FOLD 
Base Furnish / Spruce 
3,000 
2,500 
1,500 
1,000 
500 
Double Folds 
90% I 10% 80% / 20% 70% / 30% 
Pulp Batch 
BURST INDEX 
Base Furnish / Spruce 
kPam �2/g 
90% I 10% 80% / 20% 70% / 30% 
Pulp Batch 
TEAR INDEX 
Base Furnish / Spruce 
90% I 10% 80% / 20% 70% / 30% 
Pulp Batch 
Discussion of Results 
Phase 1: Preliminary Experiments 
Beater curves were obtained after testing handsheets of each 
fiber for wet tensile and fold strength. From the curves it was 
found that cotton achieved optimum strength after refining in the 
Valley beater for 45 minutes. The flax fibers, as well as the 
spruce fibers, achieved optimum strength after each was refined for 
60 minutes. 
Phase 2; Cotton / Flax Experiment 
Once the optimum refining time for each fiber was obtained, 
the experimental furnishes of cotton and flax could be created. 
The furnishes consisted of combinations of each pulp after each was 
individually refined to its optimum strength. Tests were taken on 
the handsheets made including wet tensile, fold, burst strength, 
and tear strength. 
It was determined that as the amount of flax increased, the 
strength properties also increased. By decreasing the amount of 
cotton and increasing the amount of flax, a substantial increase in 
strength was found in relation to the base experimental furnish of 
75% cotton and 25% flax. 
The ratio of 25% cotton and 75% flax fibers showed the highest 
strength values. These values were comparable to the Bureau of 
Engraving and Printing specifications. In addition, these values 
were compared with the optimum strength furnish created in a 
previous study. This furnish consisted of 80% Base Furnish (75% 
cotton / 25% flax) and 20% Hemp fibers. It was found that the 
ratio of 25% cotton and 75% flax had lower wet tensile values, 
however, achieved a greater fold strength. Wet tensile and fold 
were the only tests which could be compared due to the fact that no 
burst or tear strength values were available from the previous 
study. 
Phase 3: Spruce Experiment 
After refining the cotton, flax, and spruce to their 
respective optimum refining times for maximum strength of each 
fiber, the experimental furnishes were created. Tests were taken 
on the handsheets made from each of the three furnishes. These 
test included wet tensile, fold, burst, and tear strength. 
It was determined that as the amount of spruce fiber increased 
compared to the Base Furnish (75% cotton/ 25% flax), the strength 
properties also increased to a certain extent. The ratio of 80% 
Base Furnish and 2 0% spruce fiber showed the highest strength 
values. The addition of only 10% spruce showed an increase in 
strength compared to the base currency furnish of only cotton and 
flax fibers. Curves showed that as the spruce content reached 30%, 
strength declined for all tests taken. This could be due to the 
increase in smaller fibers compared to the lower addition of flax 
fibers which are considerably longer. 
The spruce addition level of 20% achieved strength properties 
comparable to that of the Bureau of Engraving and Printing. In 
addition, when compared to the previous study with an 80% base 
furnish and 20% hemp fiber addition, it was found that the 20% 
spruce level achieved lower wet tensile values and similar fold 
strength values. 
Conclusions 
o By increasing the flax fiber content while decreasing the
cotton fiber content, the paper strength properties
increased.
o Maximum strength properties of the cotton/flax furnishes was
achieved at 25% cotton linters and 75% flax fibers.
o Addition of spruce fibers to a currency paper furnish
increased the strength properties.
o Maximum strength properties were achieved after addition of
spruce fiber at a 20% level.
Recommendations 
1. Further work could be done to determine the exact length of
each type of fiber, for which strength is optimum. Once the 
optimum lengths have been achieved, experiments could be 
conducted to re-create the furnishes discussed in this 
project to determine if greater strength values can be 
obtained. 
2. Use of other fibers, such as eucalyptus, in replacement of
the spruce used in Phase 3 of the Experimental section.
3. Use of the distinctive red and blue fibers used by the Bureau
of Engraving and Printing in the furnishes discussed.
References 
1. Bureau of Engraving and Printing Specifications, July 7,
1987.
2. Ness, Barbara A., "Use of Manila Hemp ·Fibers in Currency
Paper", April 1993.
3. Janes, R.L., "Fiber Characteristics", TAPP! Journal,
originally presented at the 1988 TAPP! Stock Preparation
Short Course, April 13-15.
Appendix 1 
• 
• TAPPI STANDARDS 
• 
Property TAPP! Standard 
Laboratory Processing of Pulp T 200 om-85 
(Beater Method) 
Forming Handsheets For Physical T 205 om-88 
Tests of Pulp 
Freeness of Pulp T 227 om-92 
Physical Testing of Pulp T 220 om-88 
Handsheets 
Consistency (concentration) of T 240 om-88 
Pulp Suspensions 
Standard Conditioning and Testing T 402 om-88 
Atmospheres for Paper, Board, Pulp 
Handsheets, and Related Products 
Wet Tensile Strength of Paper T 456 om-87 
Folding Endurance of Paper T 511 om-88 
(MIT Tester) 
Burst strength of Paper T 403 om-85 
Internal Tearing Resistance of T 414 om-88 
Paper (Elmendorf-type Method) 
Grammage of Paper and Paperboard T 410 om-88 


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Improvement of Strength Properties for Currency Paper

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