PR-1425 Class B is an aircraft windshield and canopy 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).
This material is designed for fillet sealing of properly prepared glass, polycarbonate, acrylic and other aircraft sealing applications. This product is specifically formulated not to craze substrates.
The cured sealant exhibits excellent resistance to UV and weather exposure. PR-1425 Class B is a two-part, dichromate cured polysulfide compound. The uncured material is a low sag, thixotropic paste, suitable for application by extrusion gun or spatula. This sealant has excellent adhesion to common aircraft substrates.
Surface preparation It is recommended that plastic surfaces be abraded with 220 grit or finer sandpaper; glass surfaces should be cleaned with Cerium Oxide polish.
Immediately before applying sealant to primed substrates, the surfaces should be cleaned with solvents. Contaminants such as dirt, grease, and/or processing lubricants must be removed prior to sealant application.
A progressive cleaning procedure should be employed using appropriate solvents and a new lint-free cloth conforming to AMS 3819. (Reclaimed solvents or tissue paper should not be used.) Always pour solvent on the cloth to avoid contaminating the solvent supply. Wash one small area at a time.
It is important that the surface is dried with a second clean cloth prior to the solvent evaporating to prevent the redeposition of contaminants on the substrate. Substrate composition can vary greatly. This can affect sealant adhesion.
It is recommended that adhesion characteristics to a specific substrate be determined prior to application on production parts or assemblies.