ALL MATERIALS INCLUDE A LAYER OF FOIL

(Formerly Mil-B-131)

 WE CARRY THE FOLLOWING MIL-PRF-131K (FORMERLY MIL-B-131) MATERIALS
Material Name Brand/MFG Mil Spec DataSheet
Protect 470 MS 470 MIL-PRF-131 Class 1

PDF of Barrier Material Data Sheet

Buy Rolls of Material Online
Protect 2175 FR 2175 MIL-PRF-131 Class 1

PDF of Barrier Material Data Sheet

Protect N Cad Pak N MIL-PRF-131 Class 1

PDF of Barrier Material Data Sheet

Protect P Cad Pak P MIL-PRF-131 Class 1

PDF of Barrier Material Data Sheet

Protect PL Cad Pak PL MIL-PRF-131 Class 1

PDF of Barrier Material Data Sheet

Protect 360 MS 360 MIL-PRF-131 Class 1

PDF of Barrier Material Data Sheet

Protect 100 HD 100 MIL-PRF-131 Class 1

Protect 200 HD 200 MIL-PRF-131 Class 1

Protect 585 Tyvek 585 MIL-PRF-131 Class 1

Buy Rolls of Material Online
Protect KF Kraft Foil 1312 MIL-PRF-131 Class 2

Buy Rolls of Material Online
Protect SCRIM-B MS 1311 MIL-PRF-131 Class 3

PDF of Barrier Material Data Sheet

Buy Rolls of Material Online
Protect SCRIM-C Cad Pak S MIL-PRF-131 Class 3

PDF of Barrier Material Data Sheet

Materials are available as rolls, sheets, tubing and bags.  We make bags of all sizes!  No bag is too big.  Call us for custom quotes. 1-800-644-4032.

MILITARY PERFORMANCE SPECIFICATIONS

(THIS IS AN EXCERPT OF MIL-PRF-131K PERFROMANCE SPECIFICATIONS AS PROVIDED BY THE  US GOVERNMENT.  FOR THE  COMPLETE AND CURRENT DOCUMENT, VISIT  THE US DEPARTMENT OF DEFENSE ASSIST.DLA.MIL)

NOT MEASUREMENT
SENSITIVE
MIL-PRF-131K
18 August 2005
SUPERSEDING
MIL-PRF-131J
26 August 1998

(Formerly MIL-B-131H)

PERFORMANCE SPECIFICATION

BARRIER MATERIALS, WATERVAPORPROOF, GREASEPROOF, FLEXIBLE, HEAT-SEALABLE

This specification is approved for use by all Departments and Agencies of the Department of Defense.

1. SCOPE

Scope. This specification covers the requirements for heat-sealable, greaseproof, flexible barrier materials having low water vapor transmission characteristics for use in military packaging.

2. REQUIREMENTS

Qualification – The barrier materials furnished under this specification shall be products that are authorized by the qualifying activity for listing on the applicable qualified products list before contract award.

Material – Barrier materials shall be made from such materials and by such processes as to ensure compliance with the performance requirements of this specification.

Construction – Barrier materials shall be constructed of one or more plies in any manner which ensures compliance with the performance requirements of this specification. Butting of component materials or the finished product shall not be permitted except in the direction perpendicular to the rolling direction. When a butt weld is made on the finished product or any ply thereof, the areas shall be externally flagged with colored markers to prevent use of that portion of the roll.

Splices – A roll shall not contain more than 3 splices (4 pieces) and each piece shall be not less than 45 yards in length. Splices within rolls shall be even the entire width of the roll material and shall not come apart during unwinding of the roll. Rolls containing splices shall be flagged at both ends of each splice with colored markers to indicate splices within the roll. Barrier material in flat cut sheets shall not contain splices.

Form – The barrier material shall be furnished in rolls or flat cut sheets as specified in
the contract or order.

Rolls – Unless otherwise specified, the width of roll material shall be 36 inches, with a tolerance of plus ¼ inch or minus 1/8 inch. The average length of roll material shall be not less than 200 yards. The length of any individual roll shall be not less than 195 yards. The roll material shall be uniformly wound on nonreturnable cores. The core’s inside diameter shall be not less than 3 inches, with a tolerance of plus 1/8 inch. The length of the core shall be equal to the width of the roll material, with a tolerance of plus 1/8 inch. The core shall be rigid to prevent distortion of the roll during use and shipment conditions. Each roll shall be restrained to prevent unwinding.

Sheets – When flat cut sheets are specified, the length and width shall be as specified by the procuring activity. If the length and width tolerances for cut sheets are not specified the tolerance for each shall be plus ¼ inch or minus 1/8 inch.  Flat cut sheets shall be uniformly stacked.

Sealing – Barrier materials shall be heat-sealed under conditions recommended by the manufacturer. These sealing conditions shall be such as are considered reasonable for production line sealing operations with respect to commonly available sealing equipment and commercially practical fabrication time. The material shall exhibit no delamination at the heat-sealed area when sealed under the manufacturer’s recommended conditions. Each roll or package (flat cuts) of barrier material shall include a tag secured to the core of rolls, or sheet inserted in the package of sheets with the sealing instructions for heat-sealing on rotary, band, and jaw-type sealing equipment. The tag or sheet shall be visible upon opening the unit package.

Identification of material – The specification number, class, manufacturer’s name, manufacturer’s designation, month and year of manufacture, lot number, and heat sealing conditions (temperature, pressure, and dwell time) shall be clearly and legibly marked using water-resistant ink on the backing surface of the material. The color of the markings shall be lusterless red. The complete markings shall be continuous lengthwise and the distance between groups of markings shall be not greater than 2 inches. A complete group of markings shall appear once in each 18 inches of width of the roll. The letters and figures shall be not less than 1/8 inch high.

Performance requirements – The performance of the barrier materials shall conform to the requirements specified in table I.

Workmanship – Barrier material surfaces shall be free from any foreign matter. The barrier material edges shall be cut and trimmed of any selvage. Barrier material shall be free from holes, tears, cuts, sharp creases, wrinkles, or other imperfections.

TABLE I. Performance requirements.

Characteristics Class I Requirements Class II Requirements Class III Requirements
Seam Strength
1. As received material sealed & tested:
a. At room temperature (separation-inches)
b. At 100°F and at 160°F (separation-inches)
2. Sealed before aging at 160°F for 12 days and tested:
a. At room temperature (separation-inches)
b. At 100°F and at 160°F (separation-inches)
3. Sealed after aging at 160°F for 12 days and tested:
a. At room temperature (separation-inches)
b. At 100°F and at 160°F (separation-inches)
No separation
¼ (Max)
No separation
¼ (Max)No separation
¼ (Max)
No separation
¼ (Max)No separation
¼ (Max)No separation
¼ (Max)
No separation
¼ (Max)No separation
¼ (Max)No separation
¼ (Max)
 Seam Fabriacation No leakage at double seam junction Not required No leakage at double seam junction
 Water vapor transmission Rate (WVTR)
1. After room temperature flexing:
a. As received (gms/100 sq. in./24 hrs.)
b. Aged (gms/100 sq. in./24 hrs.)
2. WVTR after low temperature flexing:
As received (gms/100 sq. in./24 hrs.)
0.02 (max)
0.02 (max)0.03 (max)
0.02 (max)
0.02 (max)Not required
0.02 (max)
0.02 (max)0.03 (max)
Breaking strength (Grab Method)
a. As received (weakest direction) (lb/inch)
b. After aging (weakest direction) (lb/inch)
50 min
50 min
25 min
25 min
65 min
65 min
Water vapor transmission rate (WVTR) (Modulated Infrared Sensor)As received (gms/100 sq. in./24 hrs.) .0005 (max) .0005 (max) .0005 (max)
Puncture Resistance (lbs)  15 min  6 min 22 min
Tear Strength (lbs) Not Required Not Required 17 min
Backing Peel Strength (oz/in) Not Required Not Required 7.0 (min)
Aging Resistance No delamination as specified in 4.6.3.1
Blocking Resistance No blocking, delamination, or rupture
Resistance to curl No curl in excess of 5% or curl back upon itself
Contact Corrosivity No corrosion, etching, or pitting
Oil Resistanc (Delamination) No leakage, swelling, delamination, or embrittlement
Water Resistance No delamination
Water Resistance of Marking Markings on back of sheet shall be clear and legible

3. NOTES

(This section contains information of a general or explanatory nature that may be helpful,
but is not mandatory.)

Intended use – The barrier materials covered by this specification are intended for use in specialized military methods of preservation. The combination of all performance characteristics of MIL-PRF-131; seam strength and fabrication; water vapor transmission rate; breaking strength; puncture, blocking and curl resistance; contact corrosivity; delamination; and water resistance of markings provide the necessary requirements for protection from exposure to the extremes of the navy/naval aviation environment. Navy/naval aviation items are exposed to high moisture, high salt concentration, transfer at sea, rough handling, and minimal storage conditions. There are no commercial equivalents that meet the physical, mechanical, and corrosion requirements necessary to protect materiel that is exposed to the operational naval aviation environment. Specifically, Methods 41, 42, 43, 51, 52, and 53 of MIL-STD-2073-1 use MIL-PRF-131 as the premier source of barrier materials that provide watervaporproof (and watervaporproof with desiccant) protection for applicable items encountering the above conditions.

MIL-PRF-131K Class 1 (general use). Class 1 material with plastic non-woven backing is intended to
be used in all packaging applications where heat-sealable, flexible, watervaporproof, greaseproof,
barrier materials are required.

MIL-PRF-131K Class 2 (limited use). Class 2 material with kraft backing is used for packages where the combined weight inside the barrier does not exceed 10 pounds. Class 2 material should be limited to use in bags whose inside length plus width does not exceed 42 inches. Class 2 materials should not be used in floating bag applications, in packaging operations under low temperature conditions, below 32 °F where fabrication or manipulation of the material is required, or where a double seam junction is fabricated. To prevent cracking and pin holing, packages fabricated from this material should not be handled at temperatures below 32 °F.

MIL-PRF-131K Class 3 (specialized use). Class 3 is similar to Class 1 but is used for those
applications where a higher strength heat-sealable, flexible, watervaporproof, greaseproof barrier material is required.


As noted previously, this military specification has gone through multiple revisions and the version nomenclature is updated with each change.  This specification has been known as:

  • MIL-B-131
  • MIL-B-131H
  • MIL-PRF-131
  • MIL-PRF-131J
  • MIL-PRF-131K (This is the current standard adopted in August of 2015.)