Specifications for Polyester
Poly(ethylene-terephthalate) Three Sides Sealed Enclosures:
Long Side Open
Specification Number 500-531-8/26/02
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.
I. General Specifications - II.
Product Requirements - III. Inspection
A. Composition
-
Content:
Must be a clear, colorless, [biaxially oriented/stressed/drawn]
poly(ethylene-terephthalate) film such as DuPont Melinex® 516
or the equivalent.
- Impurities:
The clear and colorless polyester film must not contain any plasticizer,
surface coatings, UV inhibitors, or adsorbents and be guaranteed to
be non-yellowing with natural aging. As received, the film must not
contain any coloring agents.
B. Identification
There should be no identification marks on the film.
C. Packaging
- Inner Wrapper:
The polyester sheets must be carefully and securely packaged in 100
units or less per package.
I.D.: Each package must be identified by thickness,
size and number of items within.
- Outer Wrapper:
The items must be packed in standard commercial containers which are
constructed to ensure that they arrive at the Library of Congress
in dry, undamaged condition.
I.D.: The outside of the carton which contains the
packages should be labeled with thickness, size and number of items
in the carton, and Purchase Order or Contract number.
D. Testing
- Responsibility:
The supplier is responsible for
meeting all the requirements specified herein. 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.
- Sampling:
To sample for testing, shipments will be sampled according to MIL-STD-105E
at inspection level S-2 with an acceptance quality level of 2.5 percent
defective from each lot offered. Copies of MIL-STD-105E are available
from Naval Publications and Forms Center, Standardization Document
Order Department, Building 4, Section D, 700 Robbins Avenue, Philadelphia,
PA 19111-5094.
E. Quality Assurance Inspection
To evaluate non-tested requirements, shipments will be sampled according
to MIL-STD-105E at inspection level S-2 with an acceptable quality level
of 4.0 percent defective from each lot offered.
A. Construction, illustrated below
- Two sheets of poly(ethylene-terephthalate) of the same size should
be sealed along one long side and two short sides.
B. Seals
- Seals will be done by edge welding unless otherwise specified on
the order. Other methods will be considered if samples are sent for
evaluation.
- All seals should be complete, clear and continuous.
- All seals should not be mottled, crystallized, bubbled, brittle
or burned.
- Sealed edges should withstand moderate handling. This will be evaluated
by three methods:
- By pulling the seal between two fingernails at a 45° angle. If
the seal cracks, it is unacceptable.
- By running a finger along the inside of the seal.
- By pulling slightly at the beginning of the cut end of a sealed
edge.
- Each item must be free of planar distortions or capillary marks
("caterpillar tracks") or other indications of poor seals on all edges.
C. Workmanship
- Edges should be straight and meet exactly.
- Corners should be 90 degrees.
- Each item must be free of dents, dings, fingerprints, scratches,
abrasions, inclusions or other evidence of handling which would be
detrimental to performance.
D. Thickness
- Unless otherwise specified on the Purchase Order or Section B of
the Contract, the thickness will be:
- 3 mil for sizes 20 x 24" or smaller
- 4 mil for sizes 22 x 28" or smaller
- 5 mil for larger sizes
E. Dimensions
- Specific dimensions will be given in the Purchase Order or Section
B of the Contract.
- Tolerance must not exceed ±1/16" for total height and width
unless otherwise specified.
An examination will be made to determine whether the items comply with
the Requirements Sections. The qualities and characteristics which will
be examined include the following.
Testing Inspection
- Materials must pass all composition and performance specifications
stated in "I. General Specifications"
Visual Inspection
- Construction
- Two sheets of poly(ethylene-terephthalate) of the same size should
be sealed along one long side and two short sides.
- Seals
- Seals will be done by edge welding unless otherwise specified
on the order. Other methods will be considered if samples are sent
for evaluation.
- All seals should be complete, clear and continuous.
- All seals should not be mottled, crystallized, bubbled, brittle
or burned.
- Sealed edges should withstand moderate handling. This will be
evaluated by three methods:
- By pulling the seal between two fingernails at a 45° angle.
If the seal cracks, it is unacceptable.
- By running a finger along the inside of the seal.
- By pulling slightly at the beginning of the cut end of a sealed
edge.
- Each item must be free of planar distortions or capillary marks
("caterpillar tracks") or other indications of poor seals on all
edges.
- Workmanship
- Edges should be straight and meet exactly.
- Corners should be 90 degrees.
- Each item must be free of dents, dings, fingerprints, scratches,
abrasions, inclusions or other evidence of handling which would
be detrimental to performance.
- Thickness
- Unless otherwise specified on the Purchase Order or Section B
of the Contract, the thickness will be:
- 3 mil for sizes 20 x 24" or smaller
- 4 mil for sizes 22 x 28" or smaller
- 5 mil for larger sizes
- Tolerance
- Tolerance must not exceed ± 1/16" for total height and
width unless otherwise specified.
FAILURE TO MEET ANY OF THE SPECIFICATIONS WILL BE CAUSE FOR REJECTION.