MIL-PRF-32568
5
3.2.4 Innerspring core. The innerspring core (see 6.3.2) shall be constructed from 14.5-gauge all-wire carbon
steel to ensure that the firmness and durability requirements are met. The coils shall be assembled and fixed into
individual rows to suit the length and width of the mattress size specified. The core shall be designed to extend to
the full length and width of the finished mattress (see table III). The tolerance for the core when inside a finished
mattress shall not recede more than ½ inch in the length direction on each side and no more than ¼ inch in the width
direction on each side when measured from the mattress stitch line. The coils shall be permanently secured to
provide long-term structural stability. The coils shall be assembled into a spring core unit by helically linking the
individual coils.
3.2.5 Quilting foam. The quilting foam shall consist of flame resistant cushioning upholstery (see 6.3.11) foam
that is integral with a fabric scrim backing.
3.2.5.1 Quilting foam density. The density of quilting foam shall be 6.0±1.0 pounds per cubic foot (lb/ft³)
when tested in accordance with 4.5.1.b.
3.2.5.2 Quilting foam compression set. The compression set of the quilting foam shall be 12 percent maximum
at a 50 percent deflection when tested in accordance with 4.5.1.d.
3.2.5.3 Quilting foam tensile strength. The tensile strength of the quilting foam shall be 5.0 pounds per square
inch (lb/in
2
) minimum when tested in accordance with 4.5.1.e.
3.2.5.4 Quilting foam flammability. The quilting foam flammability shall be in accordance with the
requirements in table I when tested in accordance with table IV.
3.2.6 Insulator fabric. The insulator fabric shall be 100 percent cotton, plain weave to ensure a durable layer is
provided to protect the foam cushioning pad from spring coils and to ensure fabric will not melt or drip when
exposed to elevated temperatures. The weight shall be 3.6±0.3 ounces per square yard (oz/yd
2
), and have a
minimum thread count of 30 in the warp direction and 25 in the fill direction. The fire performance shall be as
required by table I when tested in accordance with table IV.
3.2.7 Cushioning pad (topper). The cushioning pad (see 6.3.3) shall be flame resistant synthetic foam.
3.2.7.1 Cushioning pad thickness. The thickness of the cushioning pad shall be no less than ½±
1
⁄
16
inch thick
and shall be determined in accordance with 4.5.1.a.
3.2.7.2 Cushioning pad density. The density of the cushioning pad shall be 7.2±0.7 lb/ft³ when tested in
accordance with 4.5.1.b.
3.2.7.3 Cushioning foam indentation force deflection (IFD). The cushioning foam shall have an IFD of
47±7 pounds at 25 percent deflection at a 2-inch thickness when tested in accordance with 4.5.1.c.
3.2.7.4 Cushioning pad compression set. The compression set of the cushioning pad shall be 10 percent
maximum for a 50 percent deflection when tested in accordance with 4.5.1.d.
3.2.7.5 Cushioning pad tensile strength. The tensile strength of the cushioning pad shall be 12 lb/in² minimum
when tested in accordance with 4.5.1.e.
3.2.7.6 Cushioning pad tear strength. The tear strength of the cushioning pad shall be 2.5 lb/in minimum when
tested in accordance with 4.5.1.f.
3.2.7.7 Cushioning pad resiliency. The resiliency of the cushioning pad shall be 30 percent minimum when
tested in accordance with 4.5.1.g.
3.2.7.8 Cushioning pad dry heat aging. The change in IFD after dry heat aging shall be 20 percent maximum
when tested in accordance with 4.5.1.h.
3.2.7.9 Cushioning pad foam flammability. The cushioning pad foam flammability shall be in accordance with
the requirements in table I when tested in accordance with table IV.
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