NBSIR 74-571 (O

Evaluation of Currency and

Stamp Papers

E. L. Graminski and E. E. Toth

Paper Evaluation Section

Institute for Materials Research

September 6. 1974

Progress report covering the period

January 1 ~ June 30, 1974

Prepared for Bureau of Engraving and Printing

U. S. Department of the Treasury

Washington, D. C. 20401

NBSIR 74-571

EVALUATION OF CURRENCY AND

STAMP PAPERS

E. L. Graminski and E. E. Toth

Paper Evaluation Section

Institute for Materials Research

September 6, 1974

Progress report covering the period

January 1 - June 30, 1974

NOTE,

This document has been prepared for the use of the Bureau of Engarving and Printing. Responsibility

for its further use rests with that agency.

Prepared for Bureau of Engraving and Printing

U. S. Department of the Treasury

Washington, D. C. 20401

U. S. DEPARTMENT OF COMMERCE. Frederick B. Dent. Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

•"•f.u o» "
'I
CONTENTS

Page

1 . SUmARY . . . ,

'. . . 1

2. EVALUATION OF CANDIDATE PAPERS FOR PRINTING

CURRENCY .. . ., ,3

2 . 1 Background 3

2 . 2 Experimental 4

2.3 Results and Discussion 5

2.3.1 Present-Day Currency 5

2.3.2 Experimental Currency A . 7

2.3.3 Paper SDP 8

3. MODIFICATION OF HANDSHEETS WITH ACRYLIC PJISINS

AND MELAMINE VJET STRENGTH RESIN 9

3.1 Background 9

3.2 Experimental ..... 10

3.3 Results and Discussion 12

4. WORK IN PROGRESS 13

5. BIBLIOGRAPHY 14

1 . SUMMARY

Evp.luation of Experimental Papers

As part of a continuing study for the Bureau of Engraving

and Printing of the U.S. Department of the Treasury, two v;ood

pulp papers (Paper A and Paper SDP) were evaluated for possible

use in printing currency.

As technology progresses, the possibility exists that

wood pulp papers may be as, or nearly as, durable as the

present-day currency paper. A substantial savings in cost

might result without compromising the circulation life of

currency. As new papers which appear to have the characteristics essential to currency paper are developed, evaluations

will be made to determine whether they are suitable for

currency

.

In the absence of a good means for evaluating experimental currency in circulation, laboratory methods must be relied

upon. The flexing test, developed at the National Bureau of

Standards, appears satisfactory for this purpose. It appears

to rank papers in order of their probable durability. Those

currencies exhibiting significant improvements in retention

of projierties over present-day currency in the flexing test

would be expected to have a longer circulation life. However,

no precise estimate could be given for the extent of increase

in circulption life.

The performance of experimental currency printed on Paper

A was comparable to present-day currency when flexed in the

cross direction (CD) of the paper, but its performance was

decidedly poorer when flexed in the machine direction (MD)

.

A significant decrease in the MD folding endurance, as a result of MD flexing, suggests potential tensile failure and

hole formation in currency during circulation. Thus, currency

might be removed from circulation even though it had an

acceptable level of stiffness, resulting in a corresponding

decrease in circulation life. Further investigations must be

conducted before a firm recommendation can be made on the use

of Paper A for currency.

Paper SDP is an experimental paper and was not printed

as large sheets were not available. Paper SDP was evaluated

in order to assess the feasibility of producing the experimental paper on a larger scale for a full evaluation as currency paper.
2

The retention of properties with flexing of Paper SDP

was not extraordinary, but it was recognized that this paper

might be substantially improved by saturation with acrylic

latexes. Preliminary results indicate that this is correct.

Additional paper has been obtained from the manufacturer and

further modifications and evaluations will be made during the

next reporting period

»

Resin Treatments of Handsheets

An investigation was conducted to determine the feasibility of improving stiffness retention by modifying paper

with a combination of acrylic resin and a wet strength resin.

When paper is modified with acrylic resins by beater addition,

a very porous sheet frequently results. Apparently, the

fibrils and debris formed during beating redeposits on the

fibers. This results in a marked decrease in the formation

of the film-like portion of paper which is so essential to

the retention of paper stiffness when flexed. Formation of

the film-like component must be induced if the ultimate

benefit is to be achieved from the modification of paper with

acrylic resins by beater addition. As the porosity of paper

declines when treated with melamine wet strength resin, posttreatment cf pulp, modified vzith an acrylic resin by beater

addition, may give rise to a less porous sheet. This double

treatment could result in a paper with superior stiffness

retention with flexing.

The validity of the above hypothesis was assessed by

using an acrylic resin in beater addition which produces a very porous handsheet. The results indicate clearly that

post-treatment with the wet strength resin induces formation

of the film-like material resulting in a less porous sheet.

The double treatment resulted in a significant improvement

in retention of stiffness v/ith flexing. It is anticipeited

that other acrylic resins could give origin to an even

greater improvement in stiffness retention as well as retention of all other properties. Additional investigations,

using other acrylic resins, will be performed during the next

reporting period.
3

2 . EVALUATION OF CANDIDATE PAPERS FOR

PRINTING CURRENCY

2 . 1 Baclcground

Papers may be submitted to the Bureau of Engraving and

Printing (BEP) or to the National Bureau of Standards (NBS)

to be evaluated for use in currency. Only all rag papers

were considered previously, but papers containing all or

part wood pulp now are being accepted for evaluation.

A potential currency paper must (1) exhibit good printability, (2) show high retention of bending stiffness, and

(3) maintain strength and internal tear during its circulation

life.

The ideal procedure for evaluating a new paper for

currency is to determine the circulation life of the currency

during circulation. In order to do this, the currency must

be coded in some way, and this creates a numismatic rarity.

Therefore, the coded currency is removed from circulation

in large quantities making an evaluation of its circulation

life virtually impossible. Means are available to evaluate

currency in circulation without creating a numismatic rarity,

but special recognition equipment at each Federal Reserve Bank

X'zould be necessary.

In the absence of methods for successfully evaluating

the performance of currency while in circulation, laboratory

evaluations of paper durability must be relied upon. The

flexing test developed at NBS [1] appears to evaluate satisfactorily the relative durability of paper. Since the circulation life of One Dollar Federal Reserve Notes printed on

the present currency paper is approximately 18 months, a paper

performing significantly better than the present currency

paper in the flex test should have a longer circulation life,

but the magnitude of the increase could not be estimated

precisely

.

Early evaluations of durability with the flexer were

lengthy because of the large number of flexes and samples

used in the evaluation. Experience has shown that an estimate of the retention of bending stiffness with flexing can

be made after only 1,000 flexes. Furthermore, 10,000 flexes

appear to be sufficient to indicate the tenacity of the paper.

The total evaluation time is reduced to a practical level by

using only these two levels of flexing in both the cross (CD)

and machine (MD) directions of the paper.
4

A second change was also made in the flexing procedure.

Paper is anisotropic with the result the MD modulus is approximately 2.5 times greater than the CD modulus. In an effort

to flex paper at equivalent levels of internal stress, paper

was formerly flexed over 3.18 mm rollers in the CD and over

7.94 mm rollers in the MD--a ratio of 1 to 2.5. Since currency

is probably strained in both directions to the same degree,

it was decided to evaluate the durability of currency paper

using a 3.18 mm roller in both the MD and CD directions.

During this reporting period, two wood pulp papers were

evaluated for possible use in currency. The first paper,

designated Paper A, was submitted to BEP for evaluation.

The paper was printed on the currency presses and the durability evaluation was performed on the printed paper.

The second paper (Paper SDP) also was an all wood pulp

paper and was submitted to MBS for evaluation. Paper SDP is

made from 100 percent long wood pulp fiber and is treated

with an epoxy resin according to a patented process.

An estimate of stiffness retention with flexing was done

on Paper SDP with a limited number of samples submitted by

the manufacturer. The stiffness retention was not outstanding,

and it is believed that the high porosity of this paper was

partly responsible for the low retention of stiffness. Previous work has shown that saturation of paper with certain

acrylic resins results in a decrease in paper porosity and

an increase in stiffness retention with flexing [7, 8, 9].

It was therefore decided to determine the effect of saturating

Paper SPP with acrylic resins on the retention of stiffness.

Acrylic resins AC-61 and HA-16 were chosen for this study

because good results were obtained with these resins in previous latex saturation experiments [9]

.

2 . 2 Experimental

The flexing samples (15.2 x 30.5 cm) were cut from either

32 subject sheets of printed currency or from 28 x 43 cm

sheets of Paper SDP. The samples were randomized into sets

of 10 when sufficient paper was available. Only three printed

sheets of Paper A were available so that each set consisted

of only four samples.
5

Flexing was performed on the NBS paper f lexer over 3.18

inra diameter rollers in both the MD and CD for 1,000 and 10,000

double flexes. That portion of the specimen passing over both

rollers was used for subsequent testing. The air permeability

of each sample was measured in six different locations with a commercial air permeability tester. The sample was then cut

into eight specimens as shown in Figure 1.

Cantilever stiffness was measured with the CarsonWorthington stiffness tester [12]. These specimens were then

used for the determination of internal tear according to

TAPPI T414 ts-65. A single specimen was used for each determination on an Elmendorf tear tester with a capacity of 200 g.

Folding endurance was determined according to TAPPI T511 su-69

using an MIT folding endurance tester.

Load elongation was performed on a constant rate of

loading apparatus according to TAPPI T404 ts-66, using a specimen 1.5 cm wide and a span length of 10 cm. Sonic

modulus was determined on the edge tear specimens with a commarcial apparatus according to ASTM Method F89-68 using

the two-point procedure.

Saturation of Paper SDP with acrylic resins AC-61 and

HA-16 was done with the aid of a laboratory size press using

10 percent emulsions. The paper was first weighed on an

automatic pan balance, passed through the size press at an

approximate rate of -30 cm per minute and a pressure of 6.5

kg/6.45 cra^ . The saturation sheet was dried on a drum drier

at 95°C for approximately four minutes. The dried sheet was

equilibrated 15 minutes at ambient conditions before weighing

again on the pan balance to determine weight gain.

2 . 3 Results and Discussion

2.3.1 Present-Day Currency

The only significant change occurring in any CD property

as a result of CD flexing of the present-day currency was a decline in CD cantilever stiffness. All other properties

exhibited no significant change regardless of the number of

flexes

.
6

When flexed in the MD, a significant decrease in the

initial modulus as well as in cantilever stiffness occurred

after 1,000 double flexes. After 10,000 double flexes, the

decline in modulus and cantilever stiffness increased further

and a significant change occurred in practically every MD

tensile property. These changes in MD tensile properties

after 10,000 flexes clearly indicate that this paper is more

durable in the CD than in the MD.

A cantilever stiffness of 0.9 g-cm for currency paper

flexed 1,000 times in the CD compares extremely well with

the average stiffness of redeemed currency [2, 3]. But,

while good agreement in cantilever stiffness is found Vietween

CD flexed and redeemed currency , there is no agreeuent between

any other property of laboratory flexed and redeemed currency,

at least at the levels of flexing investigated. At very high

levels of flexing there is rather good agreement between

flexed and redeemed currency [2].

One of the causes for the disparity between flexed and

redeemed currency at lower levels of flexing is the difference in the uniformity of currency flexing during circulation

and on the NBS paper f lexer. In addition to being bent or

flexed, currency in circulation is crumpled and folded

severely causing localized deterioration that has a significant effect on its tensile properties [4, 5]. Folded areas

of redeemed currency are the weakest parts of the note as

90 percent of the tensile test strips from redeemed currency

broke at one of the three principal folds found in the bills

[2]. The folds, which run perpendicular to the length of a note, are found in the center and one in each half of the

note

.

The flexing test does not duplicate the wear currency

receives in circulation, but rather it ranks papers in order

of their durability. By comparing the laboratory dui ability

of an experimental currency with that of present-day currency,

an estimate of the performance of new currency can be made.

All things being equal, currency printed on a paper having

a substantially improved stiffness retention in laboratory

flexing would be expected to have a longer circulation life

than present-day currency.

Present-day currency paper has very good durability as

indicated by a substantial circulation life of currency and

by the difficulties experienced in attempting to destruct

redeemed currency. Certainly, one approach to producing an

improved currency paper is by modifying the present-day

currency paper to bring about a significant improvement in

stiffness retention.
7

2.3.2 Experimental Currency A

The retention of properties of currency printed on

experimental currency paper A after being flexed in the CD

v^as comparable to the retention of properties of flexed

regular currency (Tables 3 and 4). Notable exceptions were

retention of CD breaking strength and energy to break after

10,000 flexes (Figure 2).

Even though retention of cantilever stiffness for both

currencies were comparable when flexed in the CD, a longer

circulation life might be expected for the experimental

currency. The initial cantilever stiffness of the experimental currency is substantially higher than regular currency,

and its stiffness is greater than regular currency after

each interval of flexing. This implies that the experimental

currency should be in an acceptable condition at the point

in time where regular currency is being redeemed for limpness.

It is assumed that the integrity and appearance of the experimental notes would be at an acceptable level.

Retention of physical properties for the experimental

currency in the MD following flexing in the MD was not

comparable to regular currency (Figure 3) . Significant

decreases in initial modulus, breaking strength, and energy

to break occurred after only 1,000 flexes. Furthermore, a significant decrease in MD folding endurance occurred after

10,000 flexes which could be of paramount importance. Twodimensional folding of a note, in the length and width

directions, gives rise to the formation of a hole in regular

currency at the point where the two folds intersect [6]

.

Because of the marked decrease in MD folding endurance with

MD flexing, the incidence of hole formation in the experimental currency might occur at a rate high enough to cause

its circulation life to be substantially lower than regular

currency despite an acceptable level of stiffness retention.

Furthermore, a greater incidence of tensile failure may occur

vrith the experimental currency as a result of flexing and

folding during circulation. These points must be examined

thoroughly before any consideration can be given to using

Paper A for currency.

Future evaluations of printed experimental currency

paper should be made on no less than 10, and preferably 20,

sheets of 32 subject currency. Too few samples may lead to

erroneous conclusions on the significance of differences in

properties. Furthermore, a method of sampling for obtaining

the 10 or 20 sheet samples should be developed.
8

As a result of the above evaluation, it dees not appear

that Paper A should be used for currency. The only advantage

in using this paper may be a lower price. As the paper

accounts only for approximately 15 percent of the total cost

o"F new currency to the Federal Reserve Banks, cne cost benefit

realized in using a less expensive currency paper may be

liquidated by the increased costs incurred in redemption and

verification. A cost benefit analysis for the overall system

is necessary in order to determine the feasibility of changing

variables such as paper in printing currency.

2.3.3 Paper SDP

Additional paper was received from the ro.anuf acturer for

the saturation investigation, l.^ut it was not idenrical to

the first paper used in the preliminary evaluation. The

porosity of the second paper was considerably lov/er than the

first and this was not detected until the sacurations and

flexing were completed. The lower porosity of the paper made

it difficult to o';tain the desired weight gain of acrylic

resin with saturation. The target v/as a 10 percent weight

gain but only a 6.4 percent weight gain V7as attained with

HA-16 and 8.7 percent with AC-61. Furthermore, saturation

was very irreuular due to a very uneven wetting of the paper.

Although T_he desired level of latex saturation was not

achieved, it was decided to proceed with tne evaluation

since an estimate of the effect of saturation on stiffness

retention was possible. The results are found in Tables 5

and 6 and the standard deviation of the results are given in

Tables 7 and 8

.

Saturation with either AC-61 or HA-16 resulted in

improved stiffness retention with flexing. Although the

weight gain of HA-16 was lower than with. AC~61, the improvement in stiffness retention was greatest with. Paper SDP

saturated with HA-16. The results indicate Paper SDP may

be suitable for currency providing it is modified with acrylic

resins

.

The above investigation will be repeated with additional

paper which has the same porosity as the paper used in the

preliminary evaluation.
9

3. MODIFICATION OF HANDSHEETS WITH ACRYLIC

RESINS AND MELAMINE WET STRENGTH RESIN

3 . 1 Background

Scanning electron photomicrographs of currency paper

indicate the presence of a film-like material or matrix

in addition to the fibers [10] . The matrix is composed of

fibrils and cell wall debris formed during the beating of

pulp. The matrix spans the areas between the fibers causing

a shortening of the effective fiber segment length and

decreases the fibers ability to move laterally or to twist

when strained. The shortening of the fiber segmental length

leads to an increase in bending stiffness, as the apparent

fiber stiffness increases with decreasing fiber length. The

constraint of fiber twisting and lateral movement makes it

more difficult to deform paper, and as a result, the modulus

of paper will be greater than in a situation where the fibers

are free to twist and move laterally.

V?hen currency paper is flexed, cracks form in the matrix

resulting in decreases in modulus and cantilever stiffness

[10] . Similar cracking has been observed in redeemed currency

[11]. The magnitude of the decline depends upon the extent

of matrix deterioration. Increasing the cracking resistance

of the ratrix would result in an improved stiffness retention

of paper v/ith flexing. As the main cause for currency redemption is loss of stiffness, an improvement in the retention

of stiffness of currency paper would result in an increased

circulation life. An apparent means of achieving an improved

stiffness retention is to improve the resistance to deterioration of the matrix in flexing.

Previous studies show that the m.elamine wet strength

resin in dry-print currency paper probably accounts for the

increased circulation life of currency printed on that paper

[8] . The addition of melamine resin to currency beater stock

also results in a substantial decrease in paper porosity.

Apparently, melamine resin induces the fibrils and debris

to form matrix to a greater degree. The increase in matrix

formation, along with the interaction of the wet strength

resin with the fibrous components of paper, probably account

for the improvement in durability of dry-print currency paper.
10

One method for improving the tenacity of the matrix is

by encapsulating the matrix components, prior to paper formation, with a suitable synthetic polymer. In effect, modification of paper with acrylic resins by beater addition

involves just such an encapsulation of the fibers. However,

beater addition with acrylic resins causes paper to become

more porous. Scanning electron photomicrographs of handsheets modified with acrylic resins by beater addition indicate a marked decline in matrix formation [9]. Apparently,

the matrix components redeposit on the fibers preventing

matrix formation. Before an encapsulation process can

produce the desired changes in the mechanical properties

of the matrix, a means must be devised to induce matrix

formation of the encapsulated matrix material.

Conceivably, enhancement of matrix formation could be

accomplished by treating the encapsulated pulp suspension

with melamine wet strength resin. Since this resin apparently

induces matrix formation in conventional papermaking, it may

also serve the same purpose with the latex treated pulp.

Latex E-631 was chosen for this investigation because

prior studies showed very porous sheets resulted when used

in beater addition experiments [7, 9]. Latex E-631 would

probably never be considered in a modification of a currency

type paper to achieve the properties sought. It was selected

merely to test the feasibility of the above hypothesis.

3 . 2 Experimental

A bleached kraft wood pulp was beaten in a PFI laboratory mill at 10 percent consistency with no clearance between

bedplate and roll for 10,000 revolutions at 3.4 kilograms

force and a relative velocity of roll to bedplate of 6 m/sec.

Forty grams of pulp were beaten for each of the variables

investigated- Six aliquots were taken from each beater run

sufficient to make a 12 x 12 inch handsheet of 70 g/m^ . An

aliquot of beater stock v;as diluted with 600 cm-' distilled

water and disintegrated for 7,500 revolutions in a British

disintegrator. The pH was adjusted to 9 using 1 N NaOH.

A retention aid was added to the pulp slurry in the amount

of 2 percent based on latex solids to be deposited on the

fibers. The retention aid was added from a sufficient

quantity of a 1 percent solution diluted with 30 cm^ distilled

water. Only two thirds of the retention aid was added at the

start. The mixture of pulp suspension and retention aid was

stirred 5 minutes prior to latex addition to exhaust the

retention aid from solution. The pH of the mixture was then

decreased to 4.0 with 0.5 N HnSO^, .
11

The acrylic emulsion was diluted with approximately

50 cm3 distilled water and added to the pulp suspension in

three equal portions with moderate stirring. Five minutes

was allowed between each addition to exhaust the acrylic

latex. Only moderate stirring was used in order not to

remove any adsorbed polymer by shearing. After all of the

latex was added, the remainder of the retention aid was

added and the mixture was stirred for an additional 5 minutes.

Handsheets v;ere then prepared if no further treatment was

necessary

.

Treatment with wet strength resin was as follows. To

the aliquot, which contained beaten fiber only, or beaten

fibers treated with acrylic latex, was added sufficient 12

percent solution of melamine resin to contain 3 percent resin

based on the weight of the fiber. The pH of the mixture was

3.4 whether the stock contained acrylic resin or not and was

stirred frequently during a 30 minute interval. At the end

of that time, one drop of 0.5 N H2SO4 v/as added and stirred

for about 1 minute.

The mixture was then transferred to the deckle box of

the handsiieet machine and a sheet was formed. The wire

containing the formed sheet was placed on a blotter, covered

with a felt, and consolidated by pressing the sheet with a 30 cm long roller weighing 22.5 kg. The sheet was removed

from the wire, placed between felts, and passed through the

roll press of the handsheet machine at the minimum pressure

possible. The pressed sheet was dried on a drum drier at

95°C for approximately 4 minutes.

One half of each sheet was used to flex 1,000 times

over 3.18 mm roller and constrained by a 700 g free hanging

weight on the NBS paper f lexer. The other half served as a control. The results are given in Tables 9 and 10 and the

standard deviation of the results are given in Tables 11 and

12.
12

3 . 3 Results and Discussion

Handsheets modified with acrylic resin E-631 by beater

adr'ition followed by treatment with melamine wet strength

resin results in a handsheet with a significantly lower air

permeability than when treated with E-631 alone. In fact,

the porosity of the acrylic-melamine resin handsheets is

significantly lower than the handsheets treated with only

melamine resin. Apparently, the lower porosity is due to

enhanced matrix formation.

The double treatment resulted in an increase in cantilever

stiffness, breaking strength, and energy to break. The effect

of the double treatment on modulus is uncertain since there

is a significant increase in the modulus of the specimens

obtained in the width direction of flex samples but not in

the length direction. A larger number of handsheets will be

necessary to test for the significance in changes in modulus.

Acrylic resin E-631 is a very soft resin so that any

increase in modulus, strength, and cantilever stiffness

would be marginal. Nevertheless, it still produced significant improvements in retention of stiffness with flexing

which indicates even better improvements are possible v/ith

other acrylic resins. This investigation will be continued

during the next reporting period using other acrylic resins.
13

4. WORK IN PROGRESS

Considerable time was devoted to determining the effect

of wet pressing on the structure and properties of handsheets

during this reporting period. Previous work showed that wet

pressing has a significant effect on the structure of paper

[9] . Since the results of investigations on handsheets will

be affected by their structure every effort must be made to

determine the variables that can affect the structure in handsheet preparation. Sufficient information must be obtained

to enable differentiation between effects produced by chemical

modification and those produced by structural changes in handsheet preparation. This information is necessary in order to

conduct meaningful mill trials to verify laboratory results.

Since the investigation on wet pressing has not been

completed, reporting will be delayed until the next reporting

period. The results will then be contained in a single

report

.

5. BIBLIOGRAPHY

1. Graminski, E. L., Forshee, B. W. , and Carter, T. J.,

Evaluation of Currency and Stamp Papers, NBS Report

8634 (February 15, 1965).

2. Graminski, E. L. and Forshee, B. W. , Evaluation of

Currency and Stamp Papers, NBS Report 9597 (July 31,

1967)

.

3. Stokesberry, D. P., Philmon, I., and Graminski, E. L.,

Evaluation of Methods for Autom.atically Determining

the Fitness of Currency, NBS Report 10 699 (February 1,

1972) .

4. Graminski, E. L., Toth, E. E., and Smith, M. A., Evaluation of Currency and Stamp Papers, NBS Report 10 8 02

(February 15 , 1972)

.

5. Graminski, E. L. and Toth, E. E., Evaluation of Currency

and Stamp Papers, NBS Report 10 912 (October 2, 1972).

6. Chaudet, J. H. and Oglesby, S. I., Folding Characteristics

of New and Redeemed Currency, BEP Report No. 004,

(November 1 , 19 71)

.

7. Graminski, E. L. and Toth, E. E., Evaluation of Currency

and Stamp Papers, NBSIR 73-124 (January 30, 1973).

8. Graminski, E. L. and Toth, E. E., Evaluation of Currency

and Stamp Papers, NBSIR 73-274 (August 15, 1973).

9. Graminski, E. L. and Toth, E. E., Evaluation of Currency

and Stamp Papers, NBSIR 74-431 (January 2, 1974).

10. Graminski, E. L. and Toth, E. E., Evaluation of Currency

and StaT"_j Papers, NBS Report 10 336 (September 17, 1970).

11. Graminski, E. L. and Toth, E. E., Evaluation of Currency

and Stamp Papers, NBS Report 10 465 (August 19, 1971).

12. Carson, F. T. and Worthington, V., Tappi 36 (1), 36-42

(1953)

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FIG 1. SPECIMEN LAYOUT FOR FLEX SAMPLES
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NbS-l MA It [. V. V.7JI

U.:.. L.t r. o. ccw. 1. 1M.:hi.K:a | lux e)K UhHOK l NO. BIBLIOGRAPHIC DATA

SHtHT NBSIR 74-571

2. Gov't Accession

No.

3. i<(,( q-jient's Accc.-^sion No.

4. Ti l LH AND SUB 1 1 1 LL

Evalu.ition of Currency and

Stamp Papers

5 . Publication Date Sept. 6, 1974

6. i'crformin^ Or^aniz.t. ion CoJr

7. Ab'TKOKc-)

E. J., Grainlnski and E. E. Toth

8. l-'crforming Or^an. lU-port No. MBSIR 7'1-^.7T '

9. I'iiUI'OilMlNO ORGANiZA'I iO-N' NAME AND ADDRLSS

NATIOHAL BliHEAU OH ST/MOARDS

DEPARTMcHT OF CO-V./.ERCE

WASHIHGTOr;. D.C. 20234

lU. 1- ro|ect/ 1 asv/ ork Unit .No. 3000443

11. Conci act/ Grant .No. \

12. Sponsor mr; G;g .ui izat i on Name and Complete Address (Street, City, State, ZIP)

Bureau of Engraving and Printing

U.S. Df.-:partinant of the Treasury

Washington, D.C. 2 04 01

13. Type of Report Period Covered P rOT^- p =5 <^ 1/1 - 6/3 0/74

14. Sponsoring A^^e.-iCy Code

j

1 "15. SUPPL1-:.MHNTARY NOTES '

I

I

16. ABSTRACT (A 2C0-word or /o.ss (actual su.Tir.iary o( most si(^tiiicant information. II document inclu(ies a si^inificsnt ; bibliography or literature survey, mention it here.) "

j As part of a continuing study for the Bureau of Engraving and ' Printing of the U.S. Department of the Treasury, two wood pulp papers j (Paper A and Paper SDP) vo.re evaluated for possible use in printing j currency and. an investigation was conducted to determine the feasibility

of improving stiffness retention by modifying paper with a com.bination

of acrylic resins and a wet strength resin i Currency printed on

Paper A was comparable to present-day currency when flexed in the cross

direction of the paper, but its performance v;as decidedly poorer v/hen

flexed in the machine direction. Further study is necessary before a

firm recomr.iendation can be made on the use of Paper A for currency.

Paper SDP showed poor retention of stiffness v/hen flexed in

either direction, but there are indications that, v;hen treated with

certain acrylic resins by the saturation technique, it might be

suitable for currency paper. The significant decrease in paper density

resulting from modifying pulp with acrylic resins by beater addition

can be inverted by a second treatm.ent with a melamine wet strength

resin prior to paper formation. Preliminary data indicate that the

double treatment can produce a paper having superior stiffness retention

with flexina.

17. KEY iORDS ('six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) » Acrylic resins; experimental currency paper; paper durability; paper

structure; stiffness retention; wet strength resins.

18. AVAILABILITY |

' Unlimited

1 x' ^ '^^ Official Distribution. Do Not Release to NTIS

1

' Order From Sup. of Doc, I'.S. Government Printing Office

Vlashin,",ton. D.C. 20 i02. SO Cat. No. CM

[

' Order t torn N'atiorial Technical Infortnaiion Service (NTIS)

S p : i n 1 1 c ! d , V i r j; i r. i a 2 2 151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

21. NO. OF PAGES

29

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

USCCMM.OC 2)04; ?-"-