Blog

How to Choose the Best Threadlocker Adhesive for Your Application (Low vs Medium vs High Strength)

Threadlocker adhesives are one-component anaerobic fluids applied to bolts and nuts to lock threaded assemblies securely. By hardening only where metal threads are in contact (and air is excluded), they replace mechanical locks like washers and resist vibration, while also sealing out leaks and corrosion. Threadlockers come in different strength classes – low (removable), medium, and high (permanent) – each suited to different use cases. Choosing the right one means matching its strength and properties to your fastener size, service needs, and environment.

Threadlocker Adhesive Strength Classes

Threadlockers are typically categorized as low-, medium-, or high-strength (plus specialized wicking grades). Each class offers a balance of holding power versus removability. In general:

• Low-Strength: Bonds that can be undone with hand tools. These are ideal for small screws or fasteners that require frequent disassembly. Low-strength products (often purple-colored) are used on delicate or low-torque joints (electronics, small panels, covers) where you want to prevent loosening but still remove the part later For example, a manufacturer’s guide notes that low-strength threadlockers are “ideal for fasteners that need to be removed routinely. ThreeBond’s own low-strength threadlocker (TB1342) is formulated for precisely this scenario – it locks small bolts against vibration but lets them be removed with standard tools.
• Medium-Strength: Provides a stronger hold but is still serviceable. Medium-strength (blue) compounds lock most general fasteners yet can be disassembled (usually with hand or powered tools) when needed. They are the workhorse for medium-duty bolts (e.g. machinery covers, housings, pumps, small engines) where occasional maintenance is needed. One guide describes medium threadlockers as having “reliable hold for fasteners up to  and notes that these can generally be undone with hand tools. ThreeBond 1322D and 1324 are medium-grade anaerobic adhesives: they cure between metal parts to lock threads firmly, yet still allow service if disassembly is required.
• High-Strength (Permanent): Delivers maximum locking power for critical joints. High-strength (red) formulations cure into an almost permanent bond that usually requires heat or special tools to remove. Use these when fasteners must never back out – for example, engine bolts, suspension parts, or structural assemblies where any loosening would be catastrophic. High-strength products typically double or triple the breakaway torque of medium grades (on the order of 200–300 in-lb on large bolts) and often specify disassembly with localized heat. ThreeBond’s high-strength TB1303 is a “super high-strength” threadlocker designed for permanent locking: once cured, it resists vibration and extreme conditions and generally cannot be removed without heating.
• Wicking (Penetrating) Grades: Special low-viscosity adhesives that flow into already-assembled threads. Wicking threadlockers allow post-assembly application – you apply a drop on top of the joint and it seeps into the fastener. This is useful for retrofit or hard-to-reach places. These penetrate small gaps and cure anaerobically just like other threadlockers.

In summary, low-strength = easy removal (for maintenance);

 medium-strength = general purpose (strong hold, periodic service); high-strength = permanent lock; and wicking = post-assembly fixing. Matching the right class to your needs is key to both reliability and serviceability.

Choosing the Right Threadlocker Adhesive : Key Considerations

When selecting a threadlocker adhesive, consider the following factors to guide your choice:

• Fastener Size & Torque: Larger bolts and higher-torque joints need stronger adhesives. As a rule of thumb, low-strength threadlockers suit fasteners below ~¼ inch (6 mm) in diameter, while medium-strength covers up to ~¾ inch (20 mm) screws; anything larger typically calls for a high-strength grade.Using too low a strength on a big bolt risks loosening, while using a high-strength on a small screw makes maintenance nearly impossible.
• Disassembly Requirements: Decide if the assembly will ever need to be taken apart. For components that require routine service (covers, filters, etc.), use low or medium-strength so they can be undone with tools. For one-time or sealed assemblies (e.g. engine internals, chassis bolts), high-strength locks are appropriate. Over-tightening a high-strength product on a part that should be serviced will create headaches later.
• Vibration & Shock: All threadlockers help resist vibration, but if an application is subject to extreme shock or impact, a higher-strength formula is safer. In heavy-machinery or off-road equipment, it’s better to err on the side of strength (medium or high) to prevent loosening under stress.
• Temperature & Environment: Some threadlockers have special high-temperature grades. If a joint sees elevated heat (exhaust, engines, heat exchangers), choose a heat-resistant adhesive. For instance, ThreeBond TB1360 is a high-temperature threadlocker rated to 200 °C for exhaust or engine applications. Most standard threadlockers are limited to ~150–180°C.
• Materials & Conditions: Threadlockers cure by contact with metal ions, so heavily plated or inactive surfaces may cure slowly. In such cases a primer can be used (ThreeBond offers primer products) to activate curing. Also, threadlocker is generally for metal threads; for plastic fasteners or substrates, ThreeBond makes other locking adhesives, but those are outside the scope of this guide.
• Application Method: Ensure the threads are clean and dry. For best results, wipe bolts/nuts with solvent to remove oil and dirt before applying threadlocker. As one industry tip puts it: “clean all mating surfaces (degrease if necessary)” before use. Apply a moderate bead of adhesive to the threads (usually just 1–2 drops on the bolt) and assemble the joint. The lockant will cure within 10–20 minutes and fully harden in 24 hours.

In short, choose low-strength if you need maintenance ease, medium-strength for everyday locking needs, and high-strength for permanent joints (with heat needed for removal).

ThreeBond Threadlocker Adhesive Products and Applications

ThreeBond offers a complete line of threadlocking adhesives across all strength levels. Key products include:

• ThreeBond 1342 (Low Strength): A removable threadlocker for small screws and bolts. TB1342 prevents loosening from vibration yet allows easy removal with hand tools. It is ideal for fasteners that require routine maintenance – such as panel screws, covers, engine reservoirs, and electronics. Its low cure strength means components can be serviced without damage (removal typically needs only ~10–20% more torque than assembly).
• ThreeBond 1344 (Fine-Thread Low Strength): An anaerobic adhesive for fine or precision threads, designed for frequent disassembly. TB1344 is color-coded blue and recommended for hydraulic/pneumatic systems, brass or aluminum parts, and precision screws. After curing it maintains sufficient holding torque to prevent rust and loosening, but “low resistance after curing” means it can be cracked loose by hand tools when needed.
• ThreeBond 1322D (Medium Strength): A general-purpose, medium-strength anaerobic threadlocker. It fills the gap between bolts and nuts, then cures to lock and seal the joint. TB1322D (free of certain phthalates) provides a reliable hold for everyday industrial fasteners but can still be undone for maintenance. Typical uses include machine frames, pump housings, gearboxes – anywhere a solid lock is needed but removal isn’t unusually difficult.
• ThreeBond 1324 (Medium Strength): Another medium-grade threadlocker with rapid cure. It offers high fixing strength once set, yet allows removal if required. This makes it suitable for bolts and studs on engines, transmissions, or industrial equipment where occasional servicing is expected. Like 1322D, TB1324 locks threads and seals against leaks, but its formulation emphasizes a fast gel-time at room temperature.
• ThreeBond 1303 (High Strength, Permanent): A super high-strength anaerobic threadlocker for permanent joints. TB1303 is engineered to “permanently secure bolts, screws, and threaded joints. Once cured it withstands heavy vibration and harsh conditions – ideal for critical fasteners that must never come loose (e.g. suspension bolts, engine cylinder heads, driveshaft bolts). Disassembly of a TB1303-lock joint requires heat or special tools, so it’s not for parts needing regular service.
• ThreeBond 1305 (High Strength, Permanent): A fast-setting anaerobic adhesive with very high locking power. TB1305 cures quickly and locks threads with a permanent bond. It has excellent chemical resistance and works on tightly-fitted metal parts. Typical applications include heavy machinery, industrial engines, or any high-load assembly where bolt backing out would cause failure. (Note: since it is permanent, TB1305 should only be used on bolts not intended for disassembly.)
• ThreeBond 1360 (High Temp Threadlocker): A medium-to-high strength threadlock adhesive formulated for high-temperature use. TB1360 penetrates fine gaps and cures to a strong bond, and it withstands continuous temperatures up to 200 °C. This makes it perfect for exhaust studs, engine blocks, turbochargers, and other hot-section fasteners. It combines good locking strength with heat resistance that ordinary threadlockers lack.
• ThreeBond TB1301B (High-Strength Threadlocker) — A low-viscosity, high-strength anaerobic threadlocker formulated for application before assembly. Apply TB1301B to the male threads and assemble the joint; it cures only in the absence of air between closely fitting metal surfaces to form a durable, permanent bond that prevents fastener loosening, leakage and corrosion. Fast-acting even on plated or inactive metals, TB1301B is ideal for heavy-duty machinery, automotive powertrain fasteners and electrical equipment where long-term, vibration-resistant locking is required.

(Other ThreeBond products: There are additional specialized anaerobic adhesives in the 1300/1400 series for niche uses like welding fittings or sensor sealants. But for bolt locking, the above products cover the full range of strength and service needs.)

FAQs

Q: What is the difference between low, medium and high strength threadlockers?
A: In simple terms: Low-strength threadlockers cure to a soft bond that you can undo with hand tools – they’re for small fasteners or parts needing maintenance. Medium-strength cures to a firm hold but can still be disassembled (often with tools like wrenches) – ideal for general industrial bolts. High-strength cures to a permanent lock: you normally have to heat the joint to remove the fastener. (See sources for a more detailed comparison.)

Q: How do I know which strength to use?
A: Match it to your application. If the screw will be removed frequently or is small (electronics, covers, maintenance panels), choose low-strength. For typical machinery where bolts stay tight but might be removed occasionally, use medium-strength. For heavy-duty or safety-critical bolts that should never loosen, use high-strength. Also factor in serviceability – if in doubt, medium-strength is a safe default for most bolts.

Q: How should I prepare parts before applying threadlocker?
A: Cleanliness is crucial. Wipe or solvent-clean both the bolt and nut threads to remove oil, grease, or dirt. As one assembly guide emphasizes: “Clean all mating surfaces (degrease if necessary)” before using threadlocker. After cleaning, dry the parts and apply the adhesive to the bolt threads (usually one or two drops), then assemble and tighten to spec. This ensures proper adhesion and full strength after curing.

Q: What’s the best way to remove a high-strength threadlocked fastener?
A: High-strength threadlockers cure very hard, so normal wrenches often aren’t enough. The standard method is heat: heat the fastener (with a heat gun or torch) to around 150–200 °C. This breaks down the adhesive’s bond (it’s anaerobic, so it softens when oxygen is reintroduced by heating). Once hot, you can unbolt the joint. (As noted in technical tips, “for red (high strength), disassembly often requires heat (typically up to 300°F/150°C)”.) Take care to heat safely and equally, and use appropriate tools.