Library of Congress Preservation Directorate

Specification Number 700-714 – 16

Specifications for Pressure Sensitive Adhesive Labels
For Application to Single Paper Sheets and Text Pages of Bound Books
For Use in Thermal Transfer Printers
This specification is provided as a public service by the Preservation Directorate of the Library of
Congress. Any commercial reproduction that implies endorsement of a product, service, or
materials, in any publication, is strictly prohibited by law. This Specification is written for L.C.
purchasing purposes and is subject to change when necessary. If you are reading a paper copy of
this specification please check our website for the most up-to-date version.

Scope
Labels that meet the requirements set forth in this specification are intended for use on paper used
for printed or written documents or the text pages of bound books designated as General Collections
materials only. These labels are not intended for use on rare or highly valuable materials, or application to
photographic materials.

1. Composition and Chemical Requirements

1.1 Face Stock

The type of face stock will be specified on the purchase order, selected by the user for the intended
application, from the following list of options. The selected material must meet the composition
requirements as stated.

1.1.1 Polyester
The polyester must be a white opaque film, 1 – 2 mil thick. The polyester must be biaxially
oriented, non-recycled film, with no plasticizers added.

1.1.2 Polypropylene
The polypropylene must be a white opaque film, 1 – 2 mil thick. Biaxial orientation is
preferred.

1.2 Adhesive
The pressure-sensitive adhesive layer must possess high permanence characteristics such that
labels, once applied, remain attached permanently and can be removed only with difficulty. The
adhesive must be clearly identifiable as an acrylic polymer or copolymer by its infra-red spectrum.

Library of Congress Preservation Directorate Specification 700-714 – 16 1

2. Physical and Performance Requirements

2.1 Color – Brightness

The color of the face stock should be white, off-white, or as specified on the purchase order. White
pigmented face stocks must have a minimum brightness of 82% as measured by directional
reflectance at 457 nm, as described in TAPPI T 452. Colored labels: samples of the desired color
will be provided to the vendor when available.

2.2 Color – Brightness Retention

The brightness of the face stock must not change more than 10 points when subjected to 28 days of
dark aging at 90°C and 50% RH. The change in brightness will be measured according to TAPPI T
452. Colored labels: acceptable levels of discoloration will be determined between the vendor and
the user.

2.3 Color Bleeding and Water Resistance

The color must show no bleeding when soaked in distilled water for 48 hours while held under
suitable weight in contact with white bond paper. The label will be applied to a white bond paper
support for this test. The label must remain adhered to the paper support during the immersion
period.

2.4 Bond Strength

The adhesive must demonstrate sufficient initial bond strength for the label to support a test
weight of 200 grams for 10 minutes.

2.4.1 Test Method

This procedure is a 90 degree peel test, modified from ASTM D 2860. The bonding strength
of the adhesive to two different substrates is assessed. Test Panels used in this test are LC
Standard Test Panels PP-1 and PP-2, and consist of two different papers applied to 3 x 6
inch sections of 40 pt. board stock meeting LC Specification 300-300. The materials used for
these LC Standard Test Panels have been selected to represent the surface characteristics of
coated and un-coated papers, such as those that might be used for text pages in General
Collection books. Information on the composition of LC Standard Test Panels can be
obtained from the Library of Congress Preservation Research and Testing Division.

2.4.1.1 Application and Curing

A set of three labels, size 1 x 2 1/2 inches is applied to each of the two Test Panels
over a Mylar window that permits only a one inch square area of the adhesive side
of the label to be in contact with the substrate, as illustrated in ASTM D 2860,
procedure B. The labels are set in place by applying firm pressure with the edge of
a 3M plastic applicator, model no. P.A.-1., to the labels in four downward strokes.
The test samples are then allowed to cure for 7 days in an environmental chamber
conditioned to 23°C and 50% RH.

Library of Congress Preservation Directorate Specification 700-714 – 16 2

 2.4.1.2 Test and Evaluation
At the end of this dwell time a 200 gram weight is suspended from the free end of
the label and timed for 10 minutes. At the end of this test period, labels must not
have peeled away from the substrate by more than 10 millimeters. Failure of this
test with either of the test panels will disqualify the stock and no further testing
need be performed.

2.5 Bond Strength after Accelerated Aging

The adhesive, once set after the initial 7-day dwell time, must remain permanently affixed to both
the face-stock and the substrate with no loss of adhesive strength for the life of the object to which
it is applied, under conditions of normal use.

2.5.1 Test Method

This procedure is a 90 degree peel test, modified from ASTM D 2860. Test Panels for this
test will be the same as that used to test initial bond strength.

2.5.1.1 Application and Exposure

A set of three labels is applied to each of the two Test Panels in the same manner as
described in section 2.4.1.1. The labels are then subjected to accelerated aging at
80°C and 50% RH for 28 days. At the end of the aging period the test samples are
placed in an environmental chamber conditioned to 23°C and 50% RH for 24 hours.

2.5.1.2 Test and Evaluation

At the end of the conditioning period the peel test is performed as in section 2.4.1.2.
At the end of this test period, labels must not have peeled away from the substrate
by more than 10 millimeters.

2.6 Curling, Lifting, Ooze

The labels must not show any sign of curling, lifting, buckling, or puckering, nor any evidence of
the adhesive oozing beyond the label edges.

2.6.1 Test Method

A set of three labels, size 1 x 1 inch, is applied to the each of the Test Panels selected for use
in section 2.3 so that the entire adhesive side of the label is in contact with the substrate.
The labels are set in place by applying firm pressure with the edge of a 3M plastic
applicator, model no. P.A.-1, to the labels in four downward strokes. The labels are then
subjected to accelerated aging at 80°C and 50% RH for 28 days. At the end of the aging
period, the labels are examined visually.

2.7 Print Fastness

The label stock must be able to accept and retain a clean, legible image from a thermal transfer
printer.

Library of Congress Preservation Directorate Specification 700-714 – 16 3

 2.7.1 Test Method
The label stock will be printed with a test pattern consisting of a sample phrase or barcode
centered on each label using the thermal transfer ribbon recommended by the vendor as
compatible with the label stock. The printer model to be used in this test will be noted on
the purchase order.

2.7.1.1 Printing Samples

Inability to print the stock on the selected printer, to obtain a clear, crisp and
complete image, or read the bar-code with a scanner will constitute a failure. Any
failure of the label stock during the printing process will disqualify the stock and no
further testing will be performed.

2.7.1.2 Test and Evaluation

A strip of 3M Tape #230 is applied over the printed test pattern on the label by
rubbing down the tape using three fingers in six firm strokes. The tape is then
peeled back at a 180 degree angle. Legible characters visible on the test tape, and/or
degradation of the printed image on the face-stock, constitute a failure. (This
method is described in Archival Copies of Thermofax, Verifax and Other Unstable
Records, Technical Information Paper No. 5, Washington, D.C., National Archives
and Records Administration, 1990).

2.8 Off-setting of Ink to Adjacent Papers

The printed image on the label must not rub off, transfer, or otherwise disfigure the paper facing
the label.

2.8.1 Test Method

This procedure follows GPO Test Method P-11, Rub Resistance of the Printed Image. This
method is described in GPO Publication 310.1, Government Printing Office Contract Terms
Quality Assurance Through Attributes Program for Printing and Binding. This test uses LC
Standard Test Papers P-1, P-2 and P-3. Information on the composition of LC Standard Test
Papers can be obtained from the Library of Congress Preservation Research and Testing
Division.

2.8.1.1 Test and Evaluation

Labels will be printed as described in section 2.7. Printed labels are attached to one
piece each of the two LC Standard Test Papers described in section 2.8.1 that have
been cut to fit the base of the Sutherland Rub Tester. The test specimen is placed on
the rubber pad on the base of the Sutherland Rub Tester, and then rubbed with that
same Test Paper, as described in GPO Test Method P-11. Density changes of 0.04 or
above, recorded on the receptor stocks, constitute a failure.

Library of Congress Preservation Directorate Specification 700-714 – 16 4

2.9 Suitability for Cold Storage
The label stock must be able to remain adhered to its substrate without lifting, curling, flagging, or
peeling during long-term exposure in the Library of Congress cold temperature storage vaults,
down to minimum conditions of -4°C and 30% RH.

2.10 Photographic Activity Test

If specified on the purchase order for use with collections of photographic materials, the labels
must pass the Photographic Activity Test (P.A.T.), meeting the criteria stipulated in sections 5.3,
6.3, and 7.2 of ISO 18916. Both the face stock and adhesive side of the label will be tested. Vendors
may wish to confirm that their products pass the P.A.T. before submitting them to the Library of
Congress for evaluation. The vendor may wish to send samples to the Image Permanence Institute
(Rochester Institute of Technology/IPI, 70 Lomb Memorial Drive, Rochester, NY 14623-5604; Tel:
585-475-5199), or other testing laboratory, to determine conformance prior to submission.

2.11 Migration and Staining

The label adhesive must not migrate into and discolor the substrate and/or cause staining of the
substrate after aging.

2.11.1 Test Method

This test measures the color (brightness) change of a paper substrate that may occur over
time when an adhesive label has been applied to it. The change in brightness will be
measured according to TAPPI T 452. This test uses LC Standard Test Papers P-1, P-2, P-3,
P-4, P-5, P-6, and P-7. Information on the composition of LC Standard Test Papers can be
obtained from the Library of Congress Preservation Research and Testing Division.

2.11.1.1 Application and Exposure

One label, size 1 x 1 inch, is applied to each of 3 separate strips of the LC Standard
Test Papers so that the entire adhesive side of the label is in contact with the
substrate. The labels are set in place by applying firm pressure with the edge of a
3M plastic applicator, model no. P.A.-1, to the labels in four downward strokes. The
labels are then subjected to accelerated aging at 80°C and 50% RH for 28 days. At
the end of the aging period the test samples are placed in an environmental
chamber conditioned to 23°C and 50% RH for 24 hours.

2.11.1.2 Measurement and Evaluation

At the end of the conditioning period a fresh label is placed on the test paper
alongside, but not touching, the aged label. The side of the test paper behind the
labels is measured for brightness. The area behind the aged label must not show
any visual evidence of discoloration of the test paper as compared to the paper
behind the fresh label. Visual evidence of discoloration, confirmed by a brightness
change of more than 3 points, constitutes a failure. This brightness change must be
clearly attributable to discoloration of the paper substrate, rather than to
discoloration of the label face-stock or yellowing of the adhesive.

Library of Congress Preservation Directorate Specification 700-714 – 16 5

2.12 Damage to Adjacent Pages
Neither the face-stock nor the adhesive must cause discoloration, stick to, or otherwise cause
damage to adjacent pages.

2.12.1 Test Method

This test is intended to simulate the effect that placing an adhesive label on a sheet of paper
in a stack of other paper sheets, or between the text pages of a closed book, may have on
adjacent pages over time. Changes in color (brightness) of the test papers are measured
according to TAPPI T 452. This test uses LC Standard Test Papers P-1, P-2, P-3 and P-4.
Information on the composition of LC Standard Test Papers can be obtained from the
Library of Congress Preservation Research and Testing Division.

2.12.1.1 Application and Exposure

One label is applied to each of three strips of the four LC Standard Test Papers, each
measuring 22 mm x 120 mm. Each of these labeled Test Papers is faced with one
strip of the same paper, backed up with 4 more strips of the same paper, so that the
face-stock is facing the first strip and is in contact with that strip. Each stack of
samples of each of the two Test Papers is placed, together, in a stainless steel test jig
to hold the papers in the stack. Each stack of paper is separated by a strip of
polyester. The stack of samples will be topped with a glass slat of the same size as
the strips. Enough stainless steel slats measuring 22 mm x 120 mm are placed on
top of the glass slat to come to a total weight (glass and metal) of 200 grams. The
samples are then subjected to accelerated aging at 90°C and 50% RH for 28 days.

2.12.1.2 Measurement and Evaluation

At the end of the aging period the labeled test strips must separate cleanly and
easily from the facing paper strips. First degree blocking, as defined by ASTM D
1146, is acceptable. However, if either the face stock, or edge-ooze of the adhesive,
has caused second degree blocking, the label will fail the test. The brightness of the
facing paper strips is measured in two separate areas. The first measurement is
taken of the area of the facing paper strip that was in contact with the face-stock on
the opposite paper strip. The second measurement is taken on an area that was not
exposed to the face-stock on the opposite strip. The two brightness measurements
must not differ by more than 3 points.

3. Product Requirements

3.1 Construction
The label stock must be provided in roll form on a hard core, with a release liner that will allow for
easy and complete peeling of the face-stock without shearing of the adhesive layer.

3.2 Workmanship
All edges of the release liner and the label stock must be cut square and clean, and sizes accurate.

Library of Congress Preservation Directorate Specification 700-714 – 16 6

3.3 Dimensions
Dimensions of the label stock, roll, and the core will be specified on the purchase order.

3.4 Odors
The label stock must not emit odors deemed objectionable or hazardous to the work environment
by the Library of Congress, when evaluated as described in TAPPI T 483.

3.5 Shelf-Life
The adhesive must have a minimum one year usable shelf-life such that the initial adhesion
strength will be the same for labels applied up to one year after the original delivery date under
ambient storage conditions. The labels must also maintain their capacity to be printed upon.

3.6 Thermal Transfer Ribbon Compatibility

The label stock must be compatible with hard-resin thermal transfer ink ribbons. Wax ribbons or
wax-resin ribbons are not acceptable. The vendor must recommend compatible printing ribbons
for the label stock, provide specification sheets (and/or performance data), a sample ribbon to be
used for testing, and purchasing information for each ribbon recommended.

4. Packaging and Identification

4.1 Inner Packages

Each package must plainly identify the type, size and number of items within, the name of the
supplier or manufacturer, year of manufacture, and manufacturing run or batch number.

4.2 Outer Package

The items must be packed in standard commercial containers that are constructed to ensure that
they arrive at the Library of Congress in dry, undamaged condition. The outside of each container
must be identified by type, size and number of items within; manufacturing run or batch number;
LC Purchase Order / Contract number and line number.

5. Compliance with Specification

5.1 Quality Assurance Testing

The Library of Congress has the right to perform any of the tests set forth in the specification
where such tests are deemed necessary to ensure that supplies conform to prescribed
requirements.

5.2 Sampling
To sample for testing, shipments will be sampled according to ANSI/ASQ Z1.4, inspection level S-
2, AQL 2.5%.

Library of Congress Preservation Directorate Specification 700-714 – 16 7

5.3 Methods
Tests will be conducted in accordance with specified test methods of the American National
Standards Institute (ANSI), the American Society for Testing and Materials (ASTM), the Technical
Association of the Pulp and Paper Industry (TAPPI), and the International Organization for
Standardization (ISO). Publications describing these tests may be ordered directly from the
technical associations, their websites, or other on-line standards vendors.

5.4 Acceptance
Materials will be accepted when the Library of Congress has ascertained that the products comply
with all parts of the specification. A partial list of the physical and chemical requirements and test
methods used to ascertain compliance is provided in a quick reference table in section 5.5.

FAILURE TO MEET ANY PART OF THE SPECIFICATION WILL BE CAUSE FOR REJECTION

5.5 Table of Physical and Chemical Requirements and Test Methods

Property Requirement Test Method

Adhesive Composition Acrylic FTIR
Color - Brightness, initial ≥ 82% TAPPI T 452
Color – Brightness Retention,
≤ 10 pts change TAPPI T 452
after dark aging
Color Bleeding No bleed / lift in 48 hours See section 2.3
Bond Strength, 7 day dwell 200g, ≤ 10 mm peel ASTM D 2860 (modified)
Bond Strength, aged 200g, ≤ 10 mm peel ASTM D 2860 (modified)
Curling/Lifting/Ooze None Visual, after aging
Print Fastness No image degradation NARA T.I.P. No. 5
Off-setting of Ink ≤ 0.04 pts density change GPO Test Method P-11
Migration/Staining, after aging ≤ 3 pts TAPPI T 452
Damage to Adjacent Pages No blocking, discoloration TAPPI T 452
Photographic Activity Test Pass ISO 18916

Library of Congress Preservation Directorate Specification 700-714 – 16 8

Configuration Management

Date Revision History

22-Oct-2002 Initial release of document on website, html format.
14-Dec-2009 Revised and reformatted for release as PDF document.
30-Sept-2016 Revised sections 2.1, 2.2, 2.3, 5.5. Editorial update to footer.

Library of Congress Preservation Directorate Specification 700-714 – 16 9