Bonding, Retaining & Sealing

About Bonding, Retaining & Sealing

Bonding, retaining and sealing products are essential chemical solutions that form the backbone of professional maintenance, repair and assembly work across countless industries. This comprehensive category encompasses specialised adhesives, sealants and locking compounds designed to bond components, retain parts under stress, seal against leaks and prevent loosening under vibration. Whether you're working in automotive repair, industrial maintenance, manufacturing or general engineering, these products deliver permanent, semi-permanent or temporary solutions for joining, sealing and securing metal, plastic, rubber and composite materials.

The category includes threadlocking compounds that prevent nuts and bolts from loosening, retaining compounds for cylindrical assemblies like bearings and bushings, gasket makers and flange sealants for leak-proof seals, and high-strength structural adhesives for bonding dissimilar materials. Surface treatments prepare components for optimal bonding and provide corrosion protection, whilst specialised formulations address specific challenges like high-temperature applications, chemical resistance or fast curing times.

Modern bonding, retaining and sealing solutions have largely replaced traditional mechanical fastening methods and cork or paper gaskets in many applications. They offer superior performance, eliminate the need for torque specifications in some assemblies, fill gaps and surface irregularities, and can be applied to components that would be difficult or impossible to join by welding or mechanical means. From maintaining hydraulic systems on construction sites to assembling precision machinery in workshops, these chemical products are indispensable for professional tradespeople and maintenance engineers.

Jargon Buster

• Anaerobic Adhesive: A type of adhesive that cures in the absence of air when confined between metal surfaces. Commonly used for threadlocking and retaining compounds, these remain liquid until assembled, then harden to create strong, vibration-resistant bonds.
• Threadlocking: The process of applying a liquid compound to threaded fasteners that cures to prevent loosening from vibration and shock. Available in different strengths from low (removable) to high (permanent) depending on application requirements.
• Retaining Compound: A high-strength adhesive designed specifically for bonding cylindrical assemblies such as bearings onto shafts, bushings into housings, or keyways. Creates a solid assembly that can withstand significant loads and thermal cycling.
• Gasketing: Formed-in-place sealants that replace traditional cut gaskets on flanges, covers and mating surfaces. These liquid or paste gaskets conform to surface irregularities and maintain a seal even when surfaces are slightly damaged or uneven.
• Wicking: The ability of low-viscosity adhesives to penetrate into pre-assembled parts through capillary action. Wicking grades are applied after assembly and flow into gaps to lock or seal components already in place.
• Shear Strength: A measurement of the maximum load a bonded joint can withstand when force is applied parallel to the adhesive layer. Critical specification when selecting products for load-bearing assemblies and structural applications.

Who Uses Bonding, Retaining & Sealing?

These specialised products are essential for a wide range of trades and industries:

• Automotive Technicians: For engine rebuilds, gearbox assembly, brake system repairs and preventing fastener loosening throughout vehicle maintenance
• Industrial Maintenance Engineers: Maintaining pumps, motors, gearboxes and production machinery with reliable sealing and component retention solutions
• Plant Fitters and Millwrights: Installing and maintaining heavy industrial equipment, securing bearings and creating leak-proof hydraulic and pneumatic connections
• Agricultural Mechanics: Repairing and maintaining farm machinery, tractors and implements exposed to vibration, weather and demanding operating conditions
• General Engineers: Manufacturing, prototyping and assembling mechanical components across diverse engineering applications
• HVAC Installers: Sealing ductwork, pipe connections and creating gas-tight joints in heating and ventilation systems
• Marine Engineers: Bonding and sealing in boat building and repair where water resistance and corrosion protection are paramount
• Plumbers and Heating Engineers: Thread sealing on gas and water fittings, and gasketing for flanged connections in heating systems

How to Choose the Right Bonding, Retaining & Sealing

Selecting the appropriate product requires careful consideration of your specific application:

Application Type: Identify whether you need threadlocking (for nuts, bolts and screws), retaining (for cylindrical assemblies), gasketing (for flange sealing), or general bonding. Each application has dedicated formulations optimised for that purpose.

Strength Requirements: Products are available in low, medium and high strength variants. Low strength allows disassembly with hand tools, medium strength requires standard tools, whilst high strength creates essentially permanent bonds requiring heat for removal. Consider future maintenance requirements when selecting strength grades.

Substrate Materials: Ensure compatibility with the materials you're bonding - metal-to-metal, metal-to-plastic, or other combinations. Some products require primers for inactive surfaces like stainless steel, aluminium or plated components.

Gap Filling: Different viscosities suit different gap sizes. Wicking grades penetrate gaps under 0.15mm, medium-viscosity products fill gaps up to 0.25mm, and high-viscosity or paste formulations handle larger clearances up to 0.5mm.

Environmental Conditions: Consider operating temperature ranges (some products withstand -55°C to +200°C or higher), chemical exposure (oils, fuels, hydraulic fluids), and whether the assembly will experience static loads or dynamic vibration.

Cure Time: Standard anaerobic products cure in 24 hours, but fast-cure variants set in minutes for production environments. Some applications benefit from accelerators to speed curing on inactive metals or in low-temperature conditions.

Compliance and Approvals: For specific industries, check for relevant certifications such as gas safety approvals, potable water standards (WRAS), or NSF ratings for food industry applications.

Popular Accessories

• Surface Primers and Activators: Prepare difficult surfaces and accelerate cure times on inactive metals, ensuring optimal bonding performance
• Applicator Bottles and Dispensers: Precision application tools for controlled product placement and reduced waste
• Surface Preparation Products: Degreasers and cleaners to remove oils, dust and contaminants before applying bonding or sealing compounds
• Aerosol Activators: Speed up curing processes, particularly useful for large gap applications or ambient temperatures below 15°C
• Thread Taps and Dies: Clean and restore threads before applying threadlocking compounds for maximum effectiveness
• Heat Guns: For applications requiring accelerated curing or when removing high-strength compounds during disassembly
• Protective Gloves: Chemical-resistant gloves suitable for handling adhesives and sealants safely

Safety Information

When working with bonding, retaining and sealing products, observe proper safety precautions to protect yourself and others. Always work in well-ventilated areas as many products release fumes during application and curing. Wear appropriate PPE including nitrile or chemical-resistant gloves to prevent skin contact, and safety glasses to protect against splashes, particularly when working overhead.

Consult the product's COSHH safety data sheet before use to understand specific hazards and control measures. Many anaerobic adhesives and sealants contain methacrylate esters which may cause skin sensitisation with repeated exposure. Avoid contact with eyes and skin, and never ingest these products. Keep containers tightly sealed when not in use and store according to manufacturer specifications, typically in cool, dry conditions away from direct sunlight.

In accordance with HSE guidelines, ensure adequate ventilation when using products in confined spaces or applying large quantities. Some sealants and surface treatments are flammable, so keep away from ignition sources, hot surfaces and naked flames. Dispose of empty containers and waste material responsibly according to local authority regulations - these products should not enter drains or watercourses.

Frequently Asked Questions

What's the difference between threadlocking and thread sealing?

Threadlocking prevents fasteners from loosening due to vibration by locking the threads together with an anaerobic adhesive. Thread sealing (using PTFE tape or liquid sealants) prevents leaks in pipe threads carrying liquids or gases. Threadlockers are used on dry assemblies like bolts and screws, whilst thread sealants are specifically for plumbing and hydraulic connections.

Can I use retaining compound on plastics?

Standard retaining compounds are formulated for metal-to-metal assemblies and may not bond effectively to plastics. Some manufacturers offer specific grades for bonding metal to plastic or plastic to plastic, but you should always verify compatibility. Cyanoacrylate or two-part epoxy adhesives are often better choices for plastic bonding applications.

How long before I can put a sealed assembly into service?

Handling strength typically develops within 10-30 minutes for most anaerobic products, allowing careful movement of parts. However, full cure and maximum strength usually requires 24 hours at room temperature. Fast-cure formulations may achieve full strength in as little as 3-6 hours. For critical applications, always wait for complete cure before applying full loads or operating pressure.

Will threadlocker work on stainless steel fasteners?

Yes, but stainless steel is an inactive metal that may require a primer or activator for optimal performance. The passive oxide layer on stainless steel can slow or prevent proper curing of anaerobic threadlockers. Using a primer ensures reliable curing and full strength development, particularly important for high-strength applications or larger diameter fasteners.

Are formed-in-place gaskets better than traditional cut gaskets?

Formed-in-place gasket makers offer several advantages: they conform perfectly to surface irregularities, don't require storage of multiple gasket sizes, resist blowout better than paper gaskets, and can seal slightly damaged flanges. However, traditional cut gaskets may still be preferred for very high-temperature applications or where specific material properties (like compressibility) are required. The best choice depends on your specific application requirements.