Loctite Threadlocker Guide: Blue, Red, Green and Purple — Which Grade Do You Need?

Choose the wrong Loctite threadlocker grade and you'll either strip a fastener trying to remove it, or find it's backed out six months later. The colour system is a shortcut, not a guarantee — purple, blue, red and green each span multiple grades with meaningfully different properties, and picking between them comes down to four variables: fastener size, service temperature, whether the joint ever needs to come apart, and whether the surface is clean.

This guide covers every Loctite threadlocker grade AIMS stocks — liquid and stick formats — with real selection criteria for maintenance, engineering and workshop applications across Australian industry.

What Is a Loctite Threadlocker?

Loctite threadlockers are anaerobic adhesives — they cure in the absence of oxygen when confined between metal surfaces. Applied to a thread, they fill the microscopic gaps between male and female threads, creating both a locking force and a seal against fluid ingress.

They're not a substitute for correct torque. A threadlocker used on an under-torqued fastener will still fail. The purpose is to resist vibration-induced loosening on correctly torqued joints, and to prevent galling and corrosion in the thread interface.

The Colour System Explained

Loctite uses colour to signal strength level. This is a starting point, not a complete specification.

The detail that catches people out: green threadlocker is a wicking grade, not a strength grade — it's defined by how it's applied (after assembly, by capillary action), not how strong the cured bond is. AIMS stocks Loctite 290, a medium-strength wicking grade; there is no high-strength wicking grade (Loctite 270) in the current AIMS range.

Loctite Threadlocker Grade Comparison Chart

⚠️ Verify before use: The specifications below are drawn from Loctite published data and AIMS's own product data sheets. Always confirm against the current Technical Data Sheet (TDS) for the specific product before applying to critical joints.

Purple Threadlocker — Loctite 222

Loctite 222 is the right choice for small fasteners that need to be removed during routine servicing. At M10 and below, red or blue threadlockers can make removal impossible without stripping the fastener or applying heat — 222 eliminates that problem.

Use 222 for:

• Grub screws and set screws (the most common use case in maintenance)
• Instrument and sensor fasteners
• Precision adjustment screws on calibrated equipment
• Any M6 or smaller fastener in a vibration environment where hand-tool removal is required

Breakaway torque on M10 (steel, 22°C): approximately 3–6 Nm — removable without heat or impact tools.

What 222 won't do: It won't lock fasteners against heavy shock or high vibration loads reliably. On M10+ fasteners, move to 243.

Shop Loctite 222 — see also the dedicated Loctite 222 guide for a deeper look at small-fastener locking.

Blue Threadlocker — Loctite 243 (and 242)

Loctite 243 is the most widely used threadlocker in Australian industry. Medium strength, suitable for M6–M20, removable with hand tools after service life, and — critically — oil-tolerant. That last property matters: 242, the predecessor to 243, required a perfectly clean, dry surface. 243 cures reliably on surfaces with minor oil contamination from handling or machining.

If you have 242 in stock, it still works fine on clean surfaces. 243 is simply the better formulation, and Loctite has made it the recommended choice for all medium-strength applications.

Use 243 for:

• General fastening in machinery, plant and equipment maintenance
• Automotive and transport applications (wheel fasteners, engine ancillaries)
• Pumps, compressors, gearboxes — where fasteners will be accessed during servicing
• Pipe fittings where a threadlocker (not thread sealant) is specified
• Any M6–M20 fastener in a vibration environment where future disassembly is expected

Breakaway torque on M10 (steel, 22°C): approximately 15–20 Nm — removable with standard spanners. On M20, hand tools still work but you may need a breaker bar.

What 243 won't do: It won't resist sustained high temperatures above 150°C. It won't hold against heavy shock on large M24+ fasteners. And it won't cure reliably on passive metals (stainless, aluminium, titanium) without Loctite 7649 Activator N.

💡 Passive metals note: Stainless steel fasteners are the most common cause of threadlocker failure in workshops. The natural oxide layer on stainless prevents anaerobic cure without an activator. Apply Loctite 7649 Primer N to both parts, allow 5 minutes to flash off, then apply 243 as normal. This is not optional.

Shop Loctite 243 | Shop Loctite 242 — see also the dedicated Loctite 243 guide.

Blue Threadlocker Stick — Loctite 248

248 is 243's medium-strength chemistry in a solid, wax-like stick applicator rather than a liquid. It applies by rubbing the stick directly onto the thread — no drip, no mess, no bottle to keep upright. On AIMS's own product data, 248 carries a 23.0 N·m breakaway torque on M10 steel with a 5-minute fixture time, service range –55°C to 150°C, and cures on all metals including passive substrates (stainless, aluminium, plated surfaces) without a primer.

Use 248 for:

• Field maintenance where a liquid bottle is impractical — overhead, vertical, or awkward-access fasteners
• Fast, no-drip application on production lines or in vehicles
• Situations where 243's liquid form would run or drip before the joint is assembled

What 248 won't do: The stick format limits how much product reaches deep into a long thread engagement compared with a liquid bead — for critical joints requiring maximum thread coverage, liquid 243 remains the more controllable option.

Shop Loctite 248

Red Threadlocker — Loctite 262, 263, 271, 272, 277

Red means permanent. The question is which red.

Loctite 262 — Standard high-strength, M6–M36. The default choice when a joint must not be removable under service loads. Used on structural fasteners, suspension components, critical machine fasteners, and any application where vibration failure would be consequential.

Loctite 263 — Functionally equivalent to 262 for most applications. Marginally different formulation. Many maintenance teams carry one or the other based on what they first standardised on — either is appropriate.

Loctite 271 — High strength, similar property profile to 262 but with a slightly different viscosity and fixture profile. Suitable for the same applications.

Loctite 272 — The choice when service temperature exceeds 150°C. Rated to 230°C continuous service. Used on exhaust system fasteners, high-temp industrial equipment, furnace components, and anywhere a standard red threadlocker would soften and lose its locking force.

Loctite 277 — The high-strength option for large fasteners, rated to M100 and above. Where 262/263/271 are specified for standard M6–M36 fastener ranges, 277's higher viscosity and bond strength are built for the larger thread engagement area of heavy structural and mining-scale fasteners.

Use red for:

• Structural fasteners not intended for field removal
• High-vibration environments: mining equipment, compressors, engines, generators
• Wheel studs, axle fasteners, chassis bolts
• Fasteners that cannot work loose without a safety consequence
• 272 specifically: exhaust manifold bolts, turbocharger fasteners, heat exchanger flange bolts
• 277 specifically: large structural bolting, heavy mining and fixed-plant fasteners above M36

Breaking strength on M10 (steel, 22°C): approximately 40–60 Nm depending on grade. Removal requires heating the fastener to 250°C minimum, then applying immediate impact or torque before cooling. Do not allow the fastener to cool before attempting removal — re-heating is required.

Removal procedure for red threadlockers:

1. Apply heat to the fastener — a blowtorch or heat gun to 250°C minimum, 300°C is safer
2. Apply removal torque immediately while still hot — within 30 seconds of removing heat
3. If the fastener cools before breaking free, re-heat and repeat
4. Do not use a cold chisel or impact alone — you will damage the thread

⚠️ Red on small fasteners: Never use red threadlocker on M8 and below unless you are certain the fastener will never need removal. Heat application in confined spaces is often impractical, and broken fasteners on small threads are a significant cost to extract.

Shop Loctite 262 | Shop Loctite 263 | Shop Loctite 271 | Shop Loctite 272 | Shop Loctite 277

Red Threadlocker Stick — Loctite 268

268 is a high-strength red threadlocker in the same non-drip stick format as 248. Rated –55°C to 150°C with a 5-minute fixture time, it's built for vertical and overhead fastener applications — pumps, gearboxes and presses — where a liquid bottle would run before the joint closes. AIMS's own product data lists a 10.0 N·m breakaway torque for the stick format; treat this as the sourced figure for the stick specifically rather than assuming it matches liquid 262/263's much higher breakaway values, since the stick's lower applied volume per thread naturally gives a lower recorded torque on the same test.

Use 268 for: permanent, high-strength locking where the stick's no-drip, no-mess application is the deciding factor over liquid 262/263 — particularly overhead or awkward-access joints in vibrating machinery.

Disassembly: heat to approximately 260°C, consistent with other high-strength red grades, then apply torque immediately while hot.

Shop Loctite 268

Green Threadlocker — Loctite 290

Green threadlocker is a wicking grade — it cures by capillary action after being applied to an assembled joint. This makes it the solution when you can't disassemble a fastener to apply threadlocker, or when you need to treat an already-assembled joint that's showing signs of loosening.

Loctite 290 — Medium-strength wicking grade. Apply around the head of an assembled fastener or at the thread engagement zone. Capillary action draws the product into the thread interface and cures in position.

Use 290 for:

• Fasteners discovered to be loose after assembly
• High-volume production where post-assembly locking is more efficient than disassembly
• Worm gears, setscrews, and adjustment screws where re-application after service is standard
• Retrofitting locking to existing equipment without full disassembly

Important: 290 does not provide reliable locking on heavily contaminated threads or joints with significant clearance. If the thread gap is too large, the wicking action won't fully penetrate and cure strength will be inconsistent. For these situations, disassemble and apply 243 conventionally. AIMS does not currently stock a high-strength wicking grade (Loctite 270) — for permanent locking on an already-assembled joint where 290's medium strength isn't enough, disassembly and a liquid red grade is the correct fallback.

Shop Loctite 290

Choosing the Right Grade: A Decision Framework

Step 1: What size is the fastener?

• M10 or smaller and needs to be removable → 222 (purple)
• M10 or smaller and permanent → 263 (red), apply carefully
• M11–M20 and needs to be removable → 243 (blue), or 248 stick for no-drip application
• M20–M36 → 262, 263 or 271 (red) for high-strength, or 243 with caution for removable joints
• Above M36 → 277 (red, large fastener grade)

Step 2: Does it ever need to come apart?

• Yes, with normal tools → 222 or 243
• Yes, but very rarely and heat is acceptable → 262, 263 or 271
• No, ever → 262, 263, 271, 277, or 272 for high-temp

Step 3: What is the service temperature?

• Up to 150°C → Any grade
• 150–230°C → 272 (red high-temp) only
• Above 230°C → No anaerobic threadlocker is rated for this; use anti-seize instead

Step 4: Is the fastener already assembled?

• No → Choose from above based on strength
• Yes and you can't disassemble it → 290 (green wicking)

Step 5: Is the surface stainless, aluminium, or titanium?

• Yes → Apply Loctite 7649 Primer N first regardless of which grade you're using

Step 6: Does the application need a no-drip stick rather than a liquid?

• Medium strength, removable → 248 (blue stick)
• High strength, permanent → 268 (red stick)

How to Apply Loctite Threadlocker

Getting application right matters. Threadlocker failures are more often application errors than product failures.

What you need:

• Loctite 7063 Cleaner/Degreaser (or equivalent solvent)
• Loctite 7649 Activator N (for stainless, aluminium, titanium only)
• Your chosen threadlocker grade
• Clean, lint-free rags

Procedure:

1. Clean both surfaces. Apply Loctite 7063 to both the male and female threads. Allow to fully evaporate — surface must be dry, not just wiped.
2. Apply activator if required. For passive metals (stainless, aluminium, titanium, zinc-plated, or cadmium-plated fasteners), apply 7649 Activator to both surfaces. Allow 5–10 minutes to flash off completely. The surface will feel slightly tacky.
3. Apply threadlocker to the thread. For liquid grades, apply a bead along the first few threads of the male fastener. For stick grades (248, 268), rub the stick directly onto the thread until a visible film transfers. The product distributes as the joint is assembled.
4. Assemble immediately. Do not allow the applied product to skin over. Assemble within 5 minutes of application.
5. Torque to specification. Apply your standard torque value. The threadlocker does not change the required torque.
6. Allow cure before loading. Handling strength (light loading) is reached in 5–30 minutes at 22°C depending on grade. Full strength requires 24 hours. At temperatures below 10°C, allow 48–72 hours for full cure.

Common mistakes:

• Applying to both surfaces when one is enough. A bead on the male thread is sufficient — applying to both is wasteful and can cause squeeze-out that blocks other functions.
• Assembling too slowly. If more than 5–10 minutes passes between application and assembly, the exposed threadlocker begins curing in air. Remove and re-apply.
• Skipping the activator on stainless. This is the single most common reason threadlockers fail on stainless fasteners.
• Using threadlocker on plated or coated fasteners without checking compatibility. Zinc-plated fasteners are typically fine with activator; nickel-plated or PTFE-coated threads require checking product compatibility.
• Applying to hot surfaces. Allow equipment to cool to under 50°C before applying anaerobic products.

How to Remove Loctite Threadlocker

Blue (222, 243, 248): Standard hand tools. On stubborn fasteners, a sharp impact from an impact driver breaks the adhesive bond cleanly. If still stuck, apply heat to 120°C — much lower than red requires.

Red (262, 263, 268, 271, 272, 277): Heat to 250°C minimum (260°C for the 268 stick). Use a gas torch or industrial heat gun. Apply removal torque immediately while hot. Do not allow to cool before breaking. If the fastener doesn't release, re-heat.

For all grades: Once removed, clean threads with Loctite 7063 before re-assembly. Old threadlocker does not prevent the new application from working, but clean threads ensure consistent results.

Threadlocker for Specific Industries

Mining and heavy equipment: Red (262/271/277 for larger fasteners) on all structural and safety-critical fasteners. Blue (243) on inspection covers, guards, and service-access fasteners. 272 on exhaust and high-heat zones.

Pumps and compressors: Blue (243) on pump casing fasteners, inspection covers, mechanical seal housing bolts. Red (263) on motor mounting bolts and structural frame fasteners. 248 stick for awkward-access covers where a liquid bottle isn't practical.

Automotive and transport: 243 for general fastening. 272 on exhaust manifold and turbocharger fasteners. 222 on grub screws and adjustment screws.

Food and beverage / pharmaceutical: Check the product's food-contact compliance status. Loctite 243 and 263 have general industrial approval; food-grade applications may require specific NSF-listed products — confirm with AIMS before specifying.

Marine: Red on any structural fastener. Additional corrosion protection is needed in conjunction — threadlocker provides locking force, not long-term corrosion protection in saltwater environments.

Frequently Asked Questions

What is the difference between red and blue Loctite?

Blue Loctite (242, 243) is medium strength, designed to be removed with standard hand tools during routine servicing. Red Loctite (262, 263, 271, 272, 277) is high strength, intended to be permanent, and typically requires heat to 250°C or above to break the bond for removal. Choose blue for anything you expect to service again; choose red only when the fastener should never come loose and rarely, if ever, needs to come apart.

What is Loctite threadlocker used for?

Loctite threadlocker is an anaerobic adhesive applied to a fastener's threads before assembly. It cures in the absence of air once the joint is closed, filling the microscopic gaps between male and female threads to resist vibration-induced loosening and to seal the thread against corrosion and fluid ingress. It is not a substitute for correct torque — it supplements a properly torqued joint rather than replacing the need for one.

Which Loctite is stronger, blue or green?

Neither is automatically stronger — they solve different problems. Blue (243) is a medium-strength grade applied before assembly. Green (290) is also medium strength, but it's a wicking grade applied after assembly by capillary action. Green isn't a strength tier above or below blue; it's defined by when and how it's applied, not by bond strength.

Which is better, Loctite 242 or 243?

243 is the updated formulation of 242. The key improvement is oil tolerance: 243 cures reliably on surfaces with minor oil contamination from handling or machining; 242 requires completely clean, dry surfaces. Both are medium-strength blue threadlockers with the same application profile. 243 is the current recommended product. If you have 242 in stock, it works fine on clean steel surfaces.

Can Loctite threadlocker be used on aluminium?

Yes, but aluminium is a passive metal that inhibits anaerobic cure. You must apply Loctite 7649 Primer N (Activator N) to both surfaces and allow it to flash off before applying the threadlocker. Without the activator, you'll get partial or no cure on aluminium.

How long does Loctite threadlocker take to cure fully?

All grades reach handling strength in 5–30 minutes at 22°C depending on the grade (stick grades 248/268 fixture in 5 minutes; most liquid grades in 20–30 minutes). Full strength is achieved at 24 hours. Below 10°C, extend to 48–72 hours. Above 22°C, cure is faster — but never assume full strength before 2 hours regardless of temperature.

What temperature does Loctite blue threadlocker withstand?

Loctite 243 is rated to 150°C continuous service. Above this temperature, the adhesive softens and locking force reduces significantly. For applications above 150°C, use Loctite 272 (rated to 230°C) — the only threadlocker grade AIMS stocks rated above 150°C.

What is the strongest Loctite threadlocker?

Among the grades AIMS stocks, 262, 263, 271 and 277 all sit in the high-strength red tier, with 277 formulated specifically for large fasteners above M36. 272 matches that strength profile while adding high-temperature resistance to 230°C. There isn't a single "strongest" grade across the whole range — the right choice depends on fastener size and service temperature as much as raw bond strength.

Can I use Loctite threadlocker on plastic fasteners?

Most Loctite threadlockers are not compatible with polycarbonate, polystyrene, or other plastic fasteners — the solvents in the product can cause stress cracking. Check the product TDS for plastic compatibility before use. Loctite 243 has limited compatibility with some engineering plastics; for plastic threads, alternative products or mechanical locking methods are typically more appropriate.

Is Loctite threadlocker the same as Permatex threadlocker?

They are competing brands with equivalent grades. Loctite 242/243 ≈ Permatex 24200/24206, Loctite 271 ≈ Permatex 27100. Performance is comparable between equivalent grades. AIMS stocks Loctite exclusively.

Can Loctite threadlocker be used on galvanised fasteners?

Galvanised (zinc-coated) fasteners inhibit anaerobic cure. Apply Loctite 7649 Activator N to both surfaces before using any threadlocker on galvanised fasteners. Without activator, expect significantly reduced cure strength.

What happens if I get Loctite threadlocker on the wrong surface?

Uncured product wipes off easily with Loctite 7063 Cleaner or acetone. Cured product in unwanted locations can be removed by soaking in Loctite 7200 Gasket Remover or acetone, then scraping — this takes time and patience. Prevention is far easier than removal.

Can I use threadlocker and anti-seize on the same fastener?

No. They serve opposite purposes. Anti-seize reduces friction to allow full torque with reduced force; threadlocker creates the locking force that prevents rotation. They chemically interfere with each other and should not be mixed. For fasteners that are difficult to remove due to corrosion rather than vibration loosening, anti-seize alone is the correct solution.

How much Loctite do I need per fastener?

A thin bead along 3–4 threads of the male fastener is sufficient for liquid grades — for stick grades (248, 268), a single pass rubbed onto the thread until a visible film transfers is enough. Excess product is squeezed out on assembly and does not improve performance. For M10 liquid application, you're looking at approximately 0.05 mL per application — a 10 mL bottle does roughly 200 M10 fasteners.

How do I use Loctite threadlocker stick versus the liquid bottle?

Rub the stick's tip directly onto the clean, dry thread until a visible film of product transfers — no drops, no runs. Assemble within 5 minutes, same as the liquid grades. Sticks (248, 268) are chosen over liquid for vertical, overhead or awkward-access joints where a bottle would drip before the fastener closes; for maximum control over how deep the product reaches into a long thread engagement, liquid remains the more precise option.

What dissolves cured Loctite threadlocker?

Cured anaerobic threadlocker resists most solvents at room temperature — that's the point of the product. Heat is the practical removal method: 120°C for blue grades, 250°C+ for red grades, applied while attempting removal torque. Acetone or a dedicated gasket/adhesive remover can soften squeeze-out on surfaces outside the thread, but won't break a fully cured joint on its own.

People Also Ask — Loctite Threadlocker

Q: What does Loctite threadlocker do?

It locks a threaded fastener against vibration-induced loosening and seals the thread against corrosion, by curing into a solid anaerobic bond once confined between the male and female threads.

Q: How to open a Loctite threadlocker bottle that's stuck?

Cured product around the cap thread is the usual cause. Warm the cap gently (a cloth soaked in warm water works) to soften any cured residue, then use pliers with a cloth for grip rather than forcing the cap — the bottle thread can shear if forced cold.

Q: Where to buy Loctite threadlocker in Australia?

AIMS Industrial stocks the full Loctite threadlocker range — 222, 242, 243, 248, 262, 263, 268, 271, 272, 277 and 290 — with same-day dispatch across Australia.

Q: How does Loctite threadlocker work?

It's an anaerobic adhesive: it stays liquid while exposed to air, then cures when confined between metal surfaces with no oxygen present. Metal ions on the thread surface trigger the cure reaction, which is why passive metals like stainless steel need an activator to cure reliably.

Related Guides

• The Complete Loctite Application Guide — full overview of all Loctite product families
• Loctite 243 Guide — deep dive on the most widely used threadlocker
• Loctite 222 Guide — small fastener and precision locking
• Loctite Retaining Compound Guide — bearing installation and cylindrical assembly
• Loctite Thread Sealant Guide — pipe and hydraulic sealing

All technical specifications should be verified against the current Loctite Technical Data Sheet for the specific product grade before use in safety-critical or regulated applications. Contact the AIMS Industrial team if you need help specifying the right product for your application.