Product Name
Loctite 242 Multi-Purpose Medium Threadlocker
Brief Description
Loctite 242 is a blue, medium-strength, thixotropic, anaerobic adhesive designed for locking and sealing threaded metal fasteners. It prevents loosening from vibration and protects against leaks, rust, and corrosion. This multi-purpose threadlocker is suitable for fasteners ranging from 1/4 inch (6 mm) to 3/4 inch (19 mm) in diameter and allows for normal disassembly with standard hand tools.
Popular Applications & Uses
- Locking and sealing threaded metal fasteners (6mm to 19mm / 1/4" to 3/4" diameter).
- Preventing loosening of metal fasteners caused by vibration and shock.
- Protecting threads from leaks, rust, and corrosion.
- Automotive applications such as valve covers, water pumps, alternators, and oil pans.
- Maintenance of light machinery, light conveyors, door hardware, and tow motors.
- Home applications including lawn mowers, grills, locksets, bicycles, and furniture.
- Securing pump or motor mounting bolts, engine rocker nuts, and equipment housing screws.
- Ideal for fasteners that require normal disassembly with standard hand tools for servicing.
Industries that Commonly Use It
- Aerospace/Defense: The Loctite brand is used in demanding applications, including military-grade products.
- Automotive Service/Repair: For various engine and vehicle component fasteners.
- Construction/Building Services: For securing door hardware and other fasteners where disassembly might be needed.
- Energy: Used for pump and motor mounting bolts in energy-related equipment.
- General Manufacturing: For light machinery, conveyors, and general industrial fastening needs.
- Industrial Supply: A common product sold through industrial supply channels.
- Marine: For fasteners in marine environments where vibration and corrosion prevention are critical.
- Metal Fabrication: For locking and sealing threaded metal assemblies.
- Prosumer: For home repairs, lawn equipment, bicycles, and furniture assembly.
- Transportation/Specialty Vehicle: For bicycles and general vehicle maintenance where removable fasteners are used.
- Distributers & Resellers: As a widely distributed industrial and consumer product.
Special and Unique Features
- Medium Strength: Allows for disassembly with standard hand tools, making it ideal for parts requiring occasional servicing.
- Anaerobic Curing: Cures in the absence of air when confined between close-fitting metal surfaces.
- Thixotropic: Prevents the liquid product from migrating or dripping after application to the substrate.
- Corrosion and Rust Protection: Effectively seals threads to prevent rust and corrosion.
- Vibration and Shock Resistance: Prevents fasteners from loosening due to operational vibrations and shocks.
- Fast Fixture Time: Sets in approximately 10 minutes on active metals (like steel), with a range of 5-20 minutes depending on the substrate.
- Controlled Lubricity: Provides accurate clamp loads during assembly.
Key Properties
- Chemical Type/Base: Dimethacrylate ester / Methacrylate.
- Color: Blue.
- Strength: Medium.
- Viscosity: Medium, 800-1600 cP (mPa·s) at 25°C.
- Fixture Time: 5-20 minutes (10 minutes on active metals).
- Full Cure Time: 24 hours.
- Temperature Range (after cure): -65°F to 300°F (-50°C to 150°C).
- Specific Gravity: Approximately 1.10.
- Flash Point: >212°F (>100°C).
- VOC Content: 0.56% by weight / 6.17 g/l.
Surface Compatibility
- Recommended for: Metal fasteners, including steel, brass, stainless steel, and plated surfaces.
- Not recommended for: Plastic parts, particularly thermoplastic materials where stress cracking could result.
- Limitations: Not for use in pure oxygen and/or oxygen-rich systems, or as a sealant for chlorine or other strong oxidizing materials. Not suitable for applications requiring “food safe” locking and sealing of fasteners.
- Preparation: For best performance, surfaces should be clean and free of grease. A primer (e.g., Loctite SF 7649) may be needed for inactive metals or low temperatures to accelerate cure.
Known backups / known substitutes
- Lockfast T42 Nutlock
- LK242 (equivalent of Henkel Loctite 242)
- 3M TL42
- Bondloc B242
- Hernon 423
- Loxeal 54-03
- Permabond A115
- General medium-strength threadlockers from brands like Permatex and Threebond.
- Vibratite (as a general threadlocker alternative).
- Non-chemical alternatives (less effective for critical applications): White plumbers thread tape, nail polish, beeswax.
Comparison Note
- Loctite 243: Often considered an upgraded, more general-purpose version of Loctite 242. It offers improved oil tolerance, allowing it to cure on as-received fasteners with minor oil contamination without prior cleaning. It also provides primerless performance on both inactive and active metals and has upgraded temperature resistance (up to 360°F / 182°C). While still medium strength, it has slightly lower shear strength, potentially making disassembly easier.
- Loctite 222 (Purple): This is a low-strength threadlocker, designed for very small fasteners that require frequent adjustment or easy removal with minimal torque.
- Loctite Red (e.g., 271): Represents high-strength, permanent threadlockers. These are used for applications where fasteners should not be removed easily and typically require localized heat (around 500°F / 250°C) for disassembly.
- Loctite Green (e.g., 290): A high-strength wicking grade threadlocker, often used for preassembled fasteners like set screws. It also requires heat and/or special chemicals for disassembly.
