Permatex Form-A-Gasket No. 3 Aviation Gasket Sealant, 16 oz Brown — Brush-Top Non-Hardening Fuel-Resistant

Permatex Aviation Form-A-Gasket No. 3 is a slow-drying, non-hardening brush-top sealant engineered for aviation and automotive sealing where a conformable, fuel- and oil-resistant gasketant is needed.

This brush-top gasket sealant provides a reliable, pliable bond for assembled parts that require some movement or frequent disassembly. Formulated to resist gasoline, oil and grease and to operate across a wide temperature span, it is suitable for close-fitting machined surfaces, hose sealing and forming solid gaskets where pre-cut or chemical gaskets are impractical.

How does this sealant perform in aircraft and automotive environments?

Form-A-Gasket No. 3 is approved for aviation use and was created to meet the demands of both aircraft and vehicle systems. Its non-hardening nature keeps flanges and fittings serviceable while offering long-term resistance to common fuels and lubricants.

• Brush-top applicator for controlled placement on mating surfaces
• Non-hardening formula preserves gasket pliability and reusability
• Resists gasoline, oil and grease for durable sealing under service fluids

What temperature range and materials is it compatible with?

This brown sealant remains effective from very low to high service temperatures, maintaining seal integrity where thermal cycling occurs. It bonds well to metals and other materials commonly used in engine compartments and aircraft fittings.

• Service range: -65°F to 400°F (-54°C to 204°C)
• Suitable for aluminum, steel and many machined surfaces
• Works on assemblies that require a resilient, conforming seal

When should I use Form-A-Gasket No. 3 instead of a pre-cut gasket?

Use this sealant when precise, close-fitting surfaces are assembled, or when a standard gasket cannot be used because of shape, access, or performance needs. It is also ideal for component repairs where a removable, non-permanent seal is preferable.

• Sealing close-fitting machined surfaces where an instant custom gasket is needed
• Forming gaskets around irregular ports and housings
• Sealing hoses and fittings that may require periodic disassembly

Packaging and application notes: The product comes in a 16 oz brush-top container for convenient, precise spreading. Because it is slow-drying and does not harden, allow adequate cure time according to assembly instructions and avoid exposing uncured sealant to fluids or extreme stress.

Who is this product for? This Permatex Form-A-Gasket No. 3 is tailored to professional mechanics, aircraft maintenance technicians, restorers and serious DIYers who need a dependable, non-hardening gasketant for fuel- and oil-exposed systems. If you require a flexible, serviceable seal for close-tolerance metal joins, hose fittings or situations where a manufactured gasket won’t fit, this sealant offers an approved, long-temperature-range solution.