Specialty Sealants
Specialized Formulations
Specialty Sealants
Specialty sealants cover chemistries built for demanding sealing applications that fall outside general-purpose epoxy, silicone, and polyurethane systems. This category currently centers on polysulfide sealants, high-performance elastomeric polymers used across aerospace, transportation, marine, and industrial environments, and will expand to include additional specialty chemistries over time.
Polysulfide sealants cure into durable, flexible rubber-like materials. Unlike rigid structural adhesives that transfer mechanical loads, they're designed to accommodate joint movement while maintaining long-term resistance to aviation fuels, hydraulic fluids, chemicals, moisture, UV exposure, and weathering. Their molecular backbone delivers durability without sacrificing elasticity, making them well suited to applications subject to vibration, thermal expansion, and pressure cycling.
From aircraft fuel tank sealing and fuselage assembly to structural glazing, expansion joints, and marine structures, polysulfide sealants provide environmental protection where long service life and chemical resistance are critical. Available in pourable, brushable, and non-sag formulations, they offer strong adhesion to metals, glass, composites, concrete, and many engineering substrates while maintaining a watertight, chemically resistant seal.
While polysulfide sealants provide strong adhesion and long-term environmental sealing, they are primarily designed to seal joints rather than carry structural loads. For high-strength permanent bonding of metals, composites, and engineering plastics, explore the dedicated Structural Epoxy Adhesives category.
Product Selector Guide
How to select the right polysulfide sealant?
For aerospace sealing applications, select polysulfide sealants based on application method, cure speed, and environmental requirements:
- Class A: Low-viscosity brush-grade sealants for coating and surface sealing.
- Class B: Extrusion-grade sealants for fillet sealing and gap filling applications.
- Class C: Roller-grade sealants designed for large-area fuel tank sealing.
- Rapid Cure: Selected when reduced processing time is required.
- Non-Chromate: Preferred where environmental compliance requirements apply.
| Product | RTU Type | Application Area | Grade / Class | Application Method | Curing Mechanism | Color | Product Features | Specifications |
| WS-8010 | Two-Part (2K) | Aircraft access doors, fillet sealing | Class B | Extrusion / Fillet | Chemical Cure at room temperature | Black / White | General purpose aerospace sealant with excellent adhesion and flexibility | AMS3284 Type 1 MIL-S-8784 |
| WS-8020RC | Two-Part (2K) | Fuel tank sealing, general aerospace sealing | Class A | Brush Application | Rapid Chemical Cure at room temperature | Black | Rapid cure, high temperature resistance, fuel resistant | AMS8802 Type 2 AMS3276 Cessna CPN021 Type 1 |
| WS-8020RC | Two-Part (2K) | Fuel tank sealing, structural sealing, high temperature applications | Class B | Extrusion / Gun Grade | Rapid Chemical Cure at room temperature | Black | Rapid curing fuel tank sealant with excellent environmental resistance | AMS3276 AMS8802 Type 2 Boeing BMS5-104 Type IV Boeing BMS3-32 Grade 2 |
| WS-8030 | Two-Part (2K) | Lightweight fuel tank sealing | Class B | Extrusion | Chemical cure at room temperature | White / Gray | Lightweight formulation with high temperature resistance | AMS3281 Type 1 |
| WS-8031 | Two-Part (2K) | Lightweight aircraft fuel tank sealing | Class B | Extrusion | Chemical Cure at room temperature | White | Lightweight sealant designed for aerospace fuel systems | AMS3281 Type 3 |
| WS-8032 | Two-Part (2K) | Fuel tank sealing and aerospace structures | Class B | Extrusion | Chemical Cure at room temperature | White | Lightweight fuel tank sealant with aerospace qualification | AMS3281 Type 2 Korea Aerospace Industries A84MS0022 |
| WS-8032 | Two-Part (2K) | Fuel tank sealing, roller application | Class C | Roller Grade | Chemical Cure at room temperature | White | Low viscosity roller grade sealant for large surface application | AMS3281 Type 2 Korea Aerospace Industries A84MS0022 |
| WS-8032S | Two-Part (2K) | Fuel tank sealing, non-chromate applications | Class B | Extrusion | Rapid Chemical Cure at room temperature | White | Lightweight, rapid cure, environmentally friendly non-chromate formulation | Bombardier BAMS552-009 Airbus A2MS552-008 |
| WS-8032S | Two-Part (2K) | Fuel tank and environmental sealing | Class C | Roller Grade | Chemical Cure at room temperature | White | Non-chromate roller grade sealant for aerospace applications | Bombardier BAMS552-009 Airbus A2MS552-008 |
| WS-8033 | Two-Part (2K) | Lightweight fuel tank sealing | Class B | Extrusion | Chemical Cure at room temperature | White | Lightweight aerospace fuel tank sealant | Embraer MEP09-084 Grade B Type 1 |
| WS-8035 | Two-Part (2K) | Fuel tank sealing | Class A | Brush Grade | Rapid Chemical Cure at room temperature | Black | Fast curing brushable fuel tank sealant | Boeing BMS5-184 |
| WS-8035 | Two-Part (2K) | Fuel tank sealing and general aerospace sealing | Class B | Extrusion | Rapid Chemical Cure at room temperature | Black | Rapid cure, general purpose aerospace sealant | Boeing BMS5-184 |
| WS-8070 | Two-Part (2K) | Corrosion protection sealing | Class B | Extrusion | Chemical Cure at room temperature | Gray | Corrosion-inhibitive aerospace sealant | MIL-PRF-81733 Class 1 Grade A Type II Cessna CPN007 Type X |
| WS-8072 | Two-Part (2K) | Corrosion protection and environmental sealing | Class B | Extrusion | Rapid Chemical Cure at room temperature | Gray | Non-chromate, lightweight corrosion inhibitive sealant | MIL-PRF-81733 Class 1 Grade B Type II AMS3265 |
Frequently Asked Questions
Frequently Asked Questions about Polysulfide Sealants
What is polysulfide sealant used for?
Polysulfide sealants are used in applications requiring strong chemical resistance, fuel resistance, flexibility, and long-term sealing reliability. They are commonly used for aircraft fuel tank sealing, aerospace structures, marine applications, insulating glass units, expansion joints, automotive sealing, and industrial assemblies exposed to oils, solvents, and harsh environmental conditions.
Is polysulfide better than silicone?
Neither technology is universally better; the right choice depends on the application requirements. Polysulfide sealants generally offer stronger resistance to fuels, oils, solvents, and gases, making them a common choice for aerospace and chemical-exposure applications. Silicone sealants generally offer better UV resistance, wider temperature capability, and stronger long-term weathering performance, making them a common choice for outdoor glazing and high-temperature sealing.
How long does polysulfide sealant last?
A properly selected and applied polysulfide sealant can provide an extended service life, supported by strong resistance to moisture, chemicals, fuel exposure, and temperature cycling that helps it maintain flexibility and sealing performance over time. Actual service life depends on the formulation, substrate compatibility, joint design, environmental exposure, and application conditions, so specific service life expectations should be confirmed against product-specific data.
Can polysulfide withstand aviation fuel?
Yes. Polysulfide sealants are widely recognized for their resistance to aviation fuels, including jet fuel and other hydrocarbon-based fluids. This fuel-resistant property makes polysulfide one of the preferred sealing technologies for aircraft fuel tanks, fuel system components, and aerospace structures where long-term resistance to aggressive chemicals is required.
How does polysulfide sealant cure?
Polysulfide sealants cure through a chemical crosslinking reaction, where the liquid polysulfide polymer reacts with a curing agent to form a flexible, three-dimensional elastomer network. Two-component systems begin curing immediately after mixing, while one-component formulations cure through exposure to environmental conditions, depending on the specific chemistry.
What is the difference between gun grade and pourable polysulfide sealants?
Gun grade polysulfide sealants are higher-viscosity, non-sag formulations designed for vertical, overhead, and controlled bead applications using dispensing equipment. Pourable polysulfide sealants have lower viscosity and are self-leveling, making them suited to horizontal joints, expansion gaps, and large-area sealing applications where complete cavity filling is required.
Are polysulfide sealants waterproof?
Yes. Once fully cured, polysulfide sealants offer strong resistance against water penetration and moisture exposure. Their low permeability and flexible, rubber-like structure help them maintain a reliable seal through weathering, thermal cycling, and prolonged outdoor exposure.
Learn More
Understanding Polysulfide Sealants
Sealant technology engineered for strong chemical resistance, fuel resistance, and long-term environmental durability
What Are Polysulfide Sealants?
Polysulfide sealants are elastomeric sealing materials based on a liquid polysulfide polymer backbone. They are engineered for applications requiring strong resistance against fuels, solvents, chemicals, moisture, and harsh environmental exposure.
Unlike silicone or polyurethane sealants, which rely on siloxane or urethane chemistry, polysulfides contain repeating sulfur-containing polymer chains that provide low gas permeability and strong resistance to hydrocarbon-based fluids.
During cure, reactive terminal groups crosslink the liquid polymer into a flexible three-dimensional elastomer network, forming a durable seal.
Strong resistance to aviation fuels, oils, solvents, hydraulic fluids, and aggressive chemicals.
The sulfur-based polymer structure provides strong barrier properties against water vapor and gases.
Maintains elasticity under temperature cycling, vibration, and continuous mechanical movement.
Types of Polysulfide Sealants
Different formulations provide different processing methods, cure profiles, and application performance
Polysulfide Curing Mechanism
The transformation from liquid polymer chains into a durable elastomeric sealing network
Liquid Polymer Before Cure
The polysulfide polymer exists as a flexible liquid chain containing reactive terminal groups. At this stage, the material remains flowable and can wet the substrate surface.
Crosslinking Reaction
The curing agent reacts with terminal functional groups, connecting individual polymer chains into a growing three-dimensional network.
Fully Cured Elastomer
The completed crosslinked rubber structure provides flexibility, chemical resistance, low permeability, and long-term sealing performance.
Key Performance Benefits
Why polysulfide sealants are a common choice for demanding sealing environments
Core Industrial Applications
Polysulfide sealants are selected where long-term sealing reliability and chemical resistance are critical
| Industry | Application |
|---|---|
| Aerospace & Aviation | Aircraft fuel tank sealing, fuselage joints, access panels, and aerospace structures requiring resistance to aviation fuels and hydraulic fluids. |
| Automotive & Transportation | Fuel system sealing, vehicle body joints, industrial equipment sealing, and applications exposed to oils and chemicals. |
| Marine & Shipbuilding | Deck joints, marine structures, underwater sealing, and applications requiring saltwater and weather resistance. |
| Construction | Expansion joints, concrete sealing, building facades, and structural gaps exposed to movement. |
| Insulating Glass | Secondary seal applications requiring low moisture and gas permeability. |
Polysulfide vs Other Sealant Technologies
General positioning across three common sealant chemistries. Actual performance varies by specific formulation and test conditions, so product-specific data should be checked before final selection.
| Property | Polysulfide | Silicone | Polyurethane |
|---|---|---|---|
| Fuel Resistance | Strong | Limited | Moderate |
| UV Resistance | Good | Strong | Good |
| Gas Permeability | Strong barrier | Moderate | Moderate |