Loctite 401 is an industrial instant adhesive used across manufacturing, maintenance, and assembly work to bond metals, plastics, rubber, ceramics, and porous materials — fast. If you’ve ever reached for a bottle of super glue and wondered whether this is the same thing, the short answer is: same chemistry, different product. Here’s everything you need to select, apply, and store it correctly.
What Is Loctite 401?
Loctite 401 is an ethyl cyanoacrylate (ECA) instant adhesive, part of Henkel’s industrial Prism range. Like all cyanoacrylates, it cures on contact with surface moisture — no mixing, no heat, no UV light required. What sets 401 apart from consumer super glues is its surface-insensitive formulation: it performs reliably on acidic or chemically treated surfaces such as chromated metals and galvanised steel, where standard cyanoacrylates often fail to achieve full strength.
The “Prism” designation refers to Henkel’s industrial-grade instant adhesive line, which includes 401, 406, 408, 454, 480, and 495 among others — each optimised for specific substrate and application requirements. Loctite 401 is the general-purpose product in that range.
Loctite 401 is not a threadlocker. If you need to secure a bolt or fitting against loosening, see our Loctite Threadlocker Guide for the right product. Threadlockers (Loctite 222, 243, 270, and others) are a completely different product class — anaerobic adhesives that cure in the absence of oxygen, not cyanoacrylates.
Loctite 401 Technical Specifications
The table below summarises the key performance properties from the Henkel technical data sheet. These values apply at 22°C unless otherwise stated.
| Property | Value |
|---|---|
| Chemistry | Ethyl cyanoacrylate (ECA) |
| Appearance | Clear, colourless liquid |
| Viscosity (Brookfield) | 100–120 mPa·s (medium viscosity) |
| Specific gravity | 1.1 at 25°C |
| Fixture time | 3–10 seconds (substrate dependent) |
| Full cure | 24 hours at 22°C |
| Operating temperature | –55°C to +80°C |
| Shear strength — steel | ~14 N/mm² |
| Shear strength — aluminium | ~12 N/mm² |
| Shear strength — NBR rubber | ~9 N/mm² |
| Maximum bond gap | <0.1 mm |
| Shelf life (unopened, 2–8°C) | 12 months |
| After opening | Use within 30 days |
| Available sizes | 3 g, 25 ml, 100 ml |
What Can Loctite 401 Bond?
Loctite 401 bonds a wide range of substrates. The table below lists typical fixture times by surface type at 22°C and 50% relative humidity. Fixture time is the point at which the assembly can be handled without disturbing the bond — full strength requires 24 hours.
| Substrate | Typical Fixture Time | Notes |
|---|---|---|
| Steel (degreased) | 3–5 seconds | Excellent adhesion |
| Aluminium | 5–10 seconds | Excellent adhesion |
| Galvanised steel | 5–10 seconds | Surface-insensitive formula performs where standard CA adhesives may not |
| Chromated / zinc-plated metal | 5–10 seconds | Surface-insensitive advantage |
| Stainless steel | 10–30 seconds | Passive surface — use activator SF 7457 if speed required |
| ABS plastic | 5–15 seconds | Good adhesion |
| Acrylic (PMMA) | 5–15 seconds | Good adhesion; avoid solvent-sensitive grades |
| Polycarbonate | 10–20 seconds | Adequate; use 406 for better results on large PC surfaces |
| Nylon / PA | 10–20 seconds | Adequate adhesion |
| NBR (nitrile rubber) | 5–10 seconds | Good adhesion, ~9 N/mm² |
| EPDM rubber | 5–15 seconds | Good adhesion; use 406 for best results |
| Natural rubber | 5–10 seconds | Good adhesion |
| Ceramic | 10–20 seconds | Good adhesion on clean, dry surfaces |
| Wood / cardboard | 5–15 seconds | Good; moisture in porous materials aids cure |
| Polyethylene (PE) | Poor without primer | Use SF 770 primer first |
| Polypropylene (PP) | Poor without primer | Use SF 770 primer first |
| PTFE (Teflon) | Poor without primer | Use SF 770 primer first |
| Silicone rubber | Very poor | Not recommended — use silicone-specific adhesive |
Is Loctite 401 the Same as Super Glue?
Same chemistry, different product. Both Loctite 401 and consumer super glues are ethyl cyanoacrylate — the underlying cure mechanism is identical. The differences are in formulation, consistency, and intended use.
| Property | Loctite 401 (Prism) | Consumer Super Glue |
|---|---|---|
| Chemistry | Ethyl cyanoacrylate | Ethyl or methyl cyanoacrylate |
| Surface sensitivity | Surface-insensitive formulation | Standard — may fail on acidic/chromated surfaces |
| Viscosity | Controlled 100–120 mPa·s | Variable, unspecified |
| Shear strength | ~14 N/mm² on steel (specified) | Not specified |
| Shelf life | 12 months (unopened, refrigerated) | Typically 12 months, variable |
| Quality consistency | Industrial-grade, batch-controlled | Variable |
| Intended use | Industrial, engineering, assembly | Household repairs, hobbyist |
For one-off household repairs, consumer super glue is fine. For industrial assembly, fixturing, or any application where bond performance needs to be predictable and repeatable, the industrial Prism range is the correct choice. The defined specs matter — 14 N/mm² shear strength means something when you’re designing a joint. An unspecified consumer product does not.
Loctite 401 vs 406 vs 480 vs 495 — Which Do You Need?
The Prism range can look confusing from the outside. Here is a direct comparison of the four most commonly used industrial instant adhesives:
| Product | Viscosity | Best For | Key Feature | Avoid For |
|---|---|---|---|---|
| 401 | Medium (100–120 mPa·s) | Metals, rigid plastics, rubber, porous materials — general purpose | Surface-insensitive; works on chromated & acidic surfaces | PE, PP, PTFE without primer; flexible joints; large gaps |
| 406 | Low (50–100 mPa·s) | Difficult plastics (ABS, PC, acrylic), elastomers, rubbers | Surface-active ingredient for low-energy plastics and elastomers | Porous materials (less effective than 401); metals where 401 is adequate |
| 480 | Medium (100–500 mPa·s, black) | Dynamic assemblies subject to shock, vibration, or impact | Rubber-toughened; flexible, impact-resistant bond | Where maximum shear strength is needed; visible joints (cures black) |
| 495 | Low (80–200 mPa·s) | General purpose metals and plastics; similar range to 401 | General-purpose CA; good all-rounder | Less surface-insensitive than 401 on chromated/acidic surfaces |
Default choice rule: Start with 401 for metal-to-metal, metal-to-rigid plastic, and most rubber applications. Move to 406 if you’re bonding flexible plastics, soft elastomers, or difficult low-energy substrates. Move to 480 if the assembly experiences dynamic loading. Add SF 770 primer if the substrate is PE, PP, or PTFE regardless of which adhesive you choose.
For threadlockers and thread sealants — completely separate products — see our Thread Locking and Sealing Guide.
When to Use Primer or Activator With Loctite 401
Most bonding with Loctite 401 requires no additional products. Two situations call for a supplementary product.
Loctite SF 770 — Polyolefin Primer
Use SF 770 when bonding polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), or thermoplastic rubbers. These are “low-energy” surfaces — cyanoacrylates cannot wet them reliably without surface activation. Apply SF 770 by brush to one bond surface, allow it to dry (30 seconds), then immediately apply Loctite 401 to the primed surface and assemble. Do not apply activator to a primed surface.
Activators — SF 7457, SF 7452, SF 7455
Use an activator when:
- The substrate is a passive metal (stainless steel, anodised aluminium, certain chromates) that cures slowly or inconsistently
- Your process requires faster than standard fixture time
- You are bonding in low-humidity conditions where atmospheric moisture is limited
Apply activator to one bond surface by brush or spray. Apply Loctite 401 to the opposite surface. Assemble immediately. The activator provides the moisture source needed to initiate polymerisation and accelerates cure from seconds to near-instantaneous. Do not saturate the surface — a thin, even coat is sufficient.
How to Apply Loctite 401
Follow these steps for a clean, strong bond.
- Clean both surfaces. Remove oil, grease, dust, and release agents with isopropanol or acetone. Dry completely. Surface contamination is the most common cause of bond failure.
- Check the fit. The joint gap must be less than 0.1 mm. If surfaces are rough or mismatched, address this before bonding. Cyanoacrylate is not a gap filler.
- Apply adhesive to one surface only. A single thin film is sufficient — typically one drop per 6–10 cm² of bond area. Less is more. Excess adhesive slows cure, reduces strength, and causes bloom.
- Assemble immediately. Position the parts and apply firm contact pressure for 5–10 seconds. Do not slide parts relative to each other after contact.
- Allow fixture time before handling. The assembly can be carefully moved after 10–30 seconds. Avoid loading the joint for at least 15 minutes; allow 24 hours before applying full design load.
- Remove excess adhesive promptly. Uncured adhesive on adjacent surfaces can be wiped with acetone before it cures. Cured adhesive can be removed mechanically or with Loctite SF 7200 debonder.
Common Failures and How to Fix Them
White residue (bloom / frosting) around the joint
Cause: Excess adhesive vapourises during cure, reacts with atmospheric moisture, and deposits as white polymer residue on nearby surfaces.
Fix: Reduce the quantity of adhesive applied. Ensure good ventilation at the bond site. In high-humidity environments, use activator to accelerate cure and minimise vapour off-gassing. Bloom is cosmetic — the bond itself is structurally sound.
Brittle bond — joint cracks or fails under vibration or impact
Cause: Loctite 401 produces a rigid bond that does not flex. Dynamic loading, vibration, or impact will crack a 401 bond line over time.
Fix: Switch to Loctite 480 (rubber-toughened cyanoacrylate) for assemblies subject to dynamic loads. If flexibility is required, consider a polyurethane or MS-polymer adhesive.
Poor adhesion or bond failure on plastics
Cause: The substrate is a low-energy plastic (PE, PP, PTFE, TPR) that CA adhesives cannot wet reliably.
Fix: Apply Loctite SF 770 polyolefin primer before bonding. For challenging plastics that are not polyolefins (e.g. silicone), the adhesive technology needed is different — neither 401 nor 406 will work reliably without an appropriate primer or alternative adhesive system.
Very slow cure on metal
Cause: Passive metal surfaces (stainless steel, anodised aluminium, certain chromates) lack the surface reactivity and moisture needed to initiate rapid CA cure.
Fix: Apply activator SF 7457 or SF 7452 to one bond surface. Assemble immediately after applying Loctite 401 to the opposite surface.
Bond weakens or fails after a short period in service
Cause: Most commonly, surface contamination prior to bonding — particularly oil or grease residue that was not fully removed. Also possible: excessive bond gap, or the joint is loaded in peel (cyanoacrylates are weak in peel — joint design should favour shear).
Fix: Degrease thoroughly before bonding. Redesign the joint to load in shear rather than peel where possible. If peel resistance is critical, use a structural epoxy instead.
Removing Loctite 401 — Debonding and Disassembly
Cured cyanoacrylate is harder to remove than people expect. There are three reliable approaches depending on the situation.
Mechanical removal
For metal-to-metal or rigid assemblies, apply heat using a hot air gun. Loctite 401 begins to degrade above 80°C. Once the bond softens, pry apart with a flat tool. The bond area will need cleaning and degreasing before re-bonding.
Chemical debonder — Loctite SF 7200
Loctite SF 7200 is a specialist debonder formulated to soften cured cyanoacrylate. Apply to the bond line and allow to soak for 30 minutes to several hours depending on joint size. The adhesive will soften enough to allow disassembly. Not suitable for all plastics — test on an inconspicuous area first.
Acetone (nail polish remover)
Acetone dissolves uncured and lightly cured cyanoacrylate effectively. For recently bonded joints that have not reached full cure, acetone applied directly to the bond line may allow disassembly. For fully cured bonds, it has limited effect without extended contact. Not suitable for polycarbonate, acrylic, or ABS plastics — acetone will craze or dissolve these surfaces.
Typical Applications in Industrial Settings
Loctite 401 appears across a wide range of industries and tasks. The following are common Australian industrial applications.
Manufacturing and assembly
Fixture bonding in production lines — temporarily or permanently locating small components during assembly before a secondary adhesive, fastener, or weld is applied. Also used for permanent bonding of nameplates, labels, gaskets, and sensor housings.
Maintenance and repair
Workshop repairs of rubber seals, gaskets, and hose fittings. Bonding cracked plastic housings, guards, and covers. Reattaching rubber bumpers, feet, and anti-vibration mounts on machinery.
Automotive and fleet
Trim and moulding bonding, rubber seal repair, interior plastic repairs. Note that Loctite 401 is not rated for continuous fuel or oil immersion — for such applications, a fuel-resistant adhesive is required.
Electronics and instrumentation
Bonding small electronic components, strain relief, sensor mounting. Loctite 401 is electrically non-conductive after cure, making it suitable for low-voltage insulating applications where the adhesive is not exposed to high temperatures.
What Loctite 401 is not suited for
Structural load-bearing applications (use structural epoxy). Joints subjected to peel loads (CA adhesives are weak in peel — redesign the joint or use epoxy). Surfaces continuously immersed in water or solvents. High-temperature applications above 80°C. Flexible or elastomeric assemblies subject to repeated flexing (use 480 or polyurethane adhesive).
Loctite 401 Storage and Shelf Life
Cyanoacrylate adhesives cure on contact with moisture — including atmospheric moisture. Storage conditions directly affect product life.
| Condition | Guidance |
|---|---|
| Unopened, refrigerated (2–8°C) | 12 months shelf life |
| Unopened, room temperature | Reduced shelf life — check date regularly |
| Opened — store at | Room temperature (NOT refrigerated) |
| After opening — use within | 30 days for best performance |
| Cap | Reseal tightly after every use |
| Keep away from | Direct sunlight, heat sources, humidity |
Why not refrigerate after opening? When a cold bottle is brought out of the fridge, it warms up and condensation forms inside the container. That moisture initiates polymerisation — effectively curing adhesive inside the bottle. Store opened product at stable room temperature and keep the cap sealed between uses.
If the adhesive is stringing, gelling, or producing poor bonds, the product has likely degraded and should be replaced. Attempting to use expired or partially cured product produces unreliable results.
Frequently Asked Questions
What is Loctite 401 used for?
Loctite 401 is a medium-viscosity instant adhesive (cyanoacrylate) designed for industrial bonding of metals, rigid plastics, rubber, ceramics, and porous materials such as wood and cardboard. It is surface-insensitive, meaning it bonds reliably on acidic or chromated surfaces where standard super glues fail. Typical applications include fixture bonding in manufacturing, rubber gasket assembly, small metal component bonding, and any application requiring a fast, strong bond on close-fitting joints.
Is Loctite 401 the same as super glue?
Loctite 401 and consumer super glue share the same chemistry — both are ethyl cyanoacrylate (ECA) — but they are not the same product. Loctite 401 is part of the industrial Prism range and is formulated to be surface-insensitive, meaning it performs reliably on difficult surfaces such as chromate-treated metals and acidic substrates where standard super glue often fails. It also has defined viscosity and shear strength specifications, a controlled shelf life, and consistent industrial-grade quality. Consumer super glues are unspecified, variable in performance, and generally unsuitable for industrial or engineering applications.
What is the difference between Loctite 401 and 406?
Both are industrial instant adhesives, but they are optimised for different applications. Loctite 401 is a general-purpose, surface-insensitive formula that bonds metals, rigid plastics, rubber, and porous materials. Loctite 406 is specifically formulated for difficult-to-bond plastics (including ABS, polycarbonate, and acrylic) and elastomers — it contains a surface-active ingredient that improves adhesion to low-energy surfaces. For most metals and mixed-substrate assemblies, 401 is the better choice. For challenging plastics and rubber applications, 406 is preferred.
Does Loctite 401 need to be refrigerated?
Unopened bottles of Loctite 401 should be stored refrigerated at 2–8°C to achieve the full 12-month shelf life. However, once opened, do NOT refrigerate the bottle. Returning an opened bottle to the fridge causes condensation inside the container when it warms up, and that moisture will prematurely cure the adhesive. After opening, store at room temperature in a dry location, keep the cap tightly sealed, and use the product within 30 days for best performance.
What is the fixture time of Loctite 401?
Loctite 401 fixtures (reaches handling strength) in 3 to 10 seconds on most substrates at room temperature, depending on the surface type, humidity level, and bond gap. Steel and aluminium typically fixture at the faster end of this range. Inactive metals such as stainless steel or anodised aluminium may be slower. Full cure to rated strength takes 24 hours at 22°C. If faster cure is needed, use activator LOCTITE SF 7457 or SF 7452 on one bond surface.
What temperature can Loctite 401 withstand?
Cured Loctite 401 has an operating temperature range of –55°C to +80°C. It maintains bond integrity through both freezing conditions and elevated heat up to 80°C. For applications requiring higher temperature resistance, consider Loctite 4014 (rated to +120°C) or a structural epoxy adhesive.
Can Loctite 401 bond rubber?
Yes, Loctite 401 bonds most common rubber types including NBR (nitrile), natural rubber, EPDM, and neoprene. On NBR rubber, the shear strength is approximately 9 N/mm². The surface-insensitive formulation helps with the variability in rubber surface chemistry. For difficult elastomers such as silicone, PTFE-based materials, or very low-energy thermoplastic rubbers, Loctite 406 combined with SF 770 primer is the more reliable choice.
Can Loctite 401 bond polyethylene or polypropylene?
Not reliably without surface preparation. Polyethylene (PE) and polypropylene (PP) are low-surface-energy plastics that resist bonding with standard cyanoacrylate adhesives, including Loctite 401. To bond PE or PP, apply Loctite SF 770 polyolefin primer to the surface, allow it to dry, then apply Loctite 401 (or 406) immediately. The primer activates the low-energy surface and enables a strong bond. Without primer, expect poor adhesion and early bond failure.
Why is my Loctite 401 turning white (blooming)?
White residue or frosting around the bond line — known as bloom — is caused by excess cyanoacrylate vapour curing on contact with ambient moisture. It happens when too much adhesive is applied, when humidity is high, or when ventilation is poor. To prevent bloom: use the minimum effective quantity of adhesive (a thin film is sufficient for close-fitting joints), ensure good ventilation, and if working in humid conditions, use activator SF 7457 to speed up cure and reduce vapour off-gassing. Bloom is cosmetic, not structural — the bond itself is unaffected.
What is the maximum gap Loctite 401 can fill?
Loctite 401 is optimised for close-fitting joints with bond gaps of less than 0.1 mm. It is not a gap-filling adhesive — performance degrades significantly with increasing gap size, and it will not bridge or fill visible gaps reliably. For loose-fitting joints or irregular surfaces with gaps of 0.1–0.5 mm, use Loctite 454 instant adhesive gel. For larger gaps or structural repairs, use an epoxy adhesive.
What is the difference between Loctite 401 and 480?
Loctite 401 produces a rigid, high-strength bond optimised for stiff assemblies and close-fitting joints. Loctite 480 is a rubber-toughened, flexible cyanoacrylate that produces a lower-strength but impact- and vibration-resistant bond — it appears black after cure. Use 401 where maximum shear strength is required on stable, non-flexing assemblies. Use 480 where the joint will experience dynamic loads, shock, or vibration, or where some bond flexibility is needed to prevent cracking.
How do I speed up Loctite 401 cure time?
Apply Loctite activator SF 7457 or SF 7452 to one bond surface before assembling the joint. The activator reacts with the cyanoacrylate on contact and accelerates cure to within seconds. This is particularly useful on passive metals (stainless steel, anodised aluminium) where natural cure can be slow. Do not apply activator to primed surfaces (SF 770). Alternatively, slightly increasing ambient humidity or temperature (within the product's working range) also speeds cure.
Buy Loctite 401 from AIMS Industrial
AIMS Industrial stocks Loctite 401 Prism Instant Adhesive in 3 g and 25 ml sizes, available online with fast Australia-wide delivery.
Shop Loctite 401 Instant Adhesive →
For other Loctite products including threadlockers, thread sealants, and retaining compounds, see our full Loctite Threadlocker and Industrial Adhesive Guide. For medium-strength threadlocker specifically, see the Loctite 243 Guide.