BOSS 326 Hi-Temp Silicone

BOSS 326 Hi-Temp Silicone is a one-part, non-slumping red silicone sealant designed for sealing, bonding, potting, encapsulating, and protective coating applications that must perform under high heat. It cures at room temperature when exposed to moisture in the air, forming a tough, rubber-like seal that helps you handle demanding industrial, appliance, and gasketing jobs with confidence.

Built for temperatures from -40°F to 500°F, BOSS 326 is ready to use straight from the container and applies easily with a cartridge, tube, or other package format. Its paste-like consistency allows for easy tooling, while its fast skin-over time supports efficient application.

Product Overview

• Type: One-part high-temperature red silicone sealant
• Consistency: Non-slumping paste
• Cure system: Moisture cure; cures on exposure to air
• Color: Red
• Use: Sealing, bonding, gasketing, potting, encapsulating, and protective coating
• Application temperature range: -35°F to 140°F
• Service temperature range: -40°F to 500°F

Key Features & Benefits

• High-temperature performance for demanding environments and heat-exposed assemblies
• Non-sag formula helps keep the material in place during vertical or overhead applications
• Fast surface cure with a skin-over time of about 6 minutes and tack-free time of about 15 minutes
• Flexible, durable seal with 500% elongation and good adhesion to many common substrates
• Ready to use with no mixing required
• Toolable consistency for cleaner joints and easier finishing

Specifications

• Flow/Slump: Nil
• Extrusion Rate: 400 g/min (1/8" orifice, 90 psi)
• Skin-over Time: 6 minutes
• Tack-free Time: 15 minutes
• Cure Time: 24 hours at 1/8" thickness
• Durometer: Shore A 25 points
• Tensile Strength: 350 psi
• Elongation: 500%
• Unprimed Adhesion: Good on most substrates
• Optimum Adhesion: Typically achieved in 7 to 10 days
• Reactive VOC: 23 g/L (<3% wt.)

Applications

BOSS 326 is made for high-heat sealing and bonding jobs where long-term flexibility and temperature resistance matter. Typical applications include:

• Sealing and encapsulating heating elements in appliances
• Aerospace gasketing
• Moving oven belts
• Industrial ovens
• Bag filters on smokestacks
• Critical bonding, sealing, potting, encapsulating, and protective coating applications exposed to elevated temperatures

Usage Instructions

Bonding

1. Clean and degrease metal and plastic surfaces thoroughly. Rinse all surfaces except plastic with acetone. Roughen rubber surfaces with sandpaper, then wipe with acetone. Follow all solvent label precautions.
2. Apply BOSS 326 in a uniform thickness. Best adhesion is typically obtained with a 15 to 30 mil glue line.
3. Join surfaces using enough pressure to remove trapped air without forcing out the adhesive.
4. Allow the assembly to stand undisturbed at room temperature while curing.

Sealing

1. Prepare the surface as needed and prime if required.
2. Force the sealant into the joint or seam to ensure full contact with both surfaces.
3. Tool the bead promptly for a smooth finish.

Cure and Performance Notes

• Cure progresses inward from the exposed surface.
• Sections up to 1/8" thick cure in about 24 hours at 77°F and 50% relative humidity.
• Thicker sections require more time; a 1/2" cross-section may need 3 to 4 days for complete solidification.
• Confined applications can slow cure significantly and may prevent full cure in some cases.
• Metal-to-metal bonds should not overlap more than 1 inch in confined applications.
• All confined-use applications should be thoroughly tested before commercial use.

Packaging

• 10.1 oz. Cartridge
• 8 oz. Pressurized Aerosol Can
• 3 oz. Blistercard
• 3 oz. Tube

Storage & Shelf Life

• Shelf life: 12 months from date of shipment when stored unopened at or below 90°F (32°C)
• Store in a covered, well-ventilated warehouse
• Avoid excessive heat and humidity
• Store cartons upright with nozzle tip pointed upward
• Do not stack cartons on their side
• Do not stack cartons more than 8 high
• Do not store within 4 feet of the warehouse or building roofline

Compliance & Specifications

• NSF Standard 51
• UL Recognized
• TT-S-001543A
• TT-S-00230C
• ASTM C920, Type S, Grade NS, Class 25, Use G, A, M, O
• Meets FDA/USDA requirements for use in establishments operating under the Federal Meat and Poultry Inspection Program when cured and washed

Safety Information

• Uncured sealant irritates eyes and may irritate skin.
• Overexposure to vapor may irritate eyes, nose, and throat.
• Use only outdoors or in a well-ventilated area.
• Avoid eye and skin contact.
• Do not handle contact lenses with sealant on your hands.
• In case of eye contact, flush with water for 15 minutes and seek medical attention.
• In case of skin contact, remove material from skin and flush with water.
• During cure, the product releases acetic acid and may have a vinegar-like odor.
• Keep out of reach of children.
• For safe handling information, consult the Safety Data Sheet (SDS).

BOSS 326 Hi-Temp Silicone is a practical choice for professionals who need a ready-to-use, high-temperature silicone sealant that delivers flexible performance, solid adhesion, and dependable results in demanding environments.