PR-1428 Class B is a low adhesion sealant. It has a service temperature range from -65°F (-54°C) to 250°F (121°C), with intermittent excursions up to 275°F (135°C). The material is designed for use as an access door sealant or in the fabrication of form-in- place (FIP) gaskets. It can also be used to protect electrical wires, terminals and equipment against fuel, moisture, dirt and short circuits.

PR-1428 Class B is a two-part, manganese dioxide cured, polysulfide compound. The uncured material is a low sag, thixotropic paste suitable for application by extrusion gun or spatula. It cures at room temper- ature to form a removable seal to common aircraft substrates.

The following tests are in accordance with MIL-S- 8784 Class B and other OEM specification test meth- ods.