Product details
| Grade | Loctite 243 |
| Strength | Medium strength |
| Colour | Blue |
| Family | Threadlockers |
| Brand | Loctite (Henkel) |
| Stock | Held in Dubai — buy one or bulk |
Pack sizes
Prices on request. Tell us the quantity you need.
Check stockWhat Loctite 243 is for
The workhorse blue threadlocker, and the one most people mean when they say "Loctite". It locks and seals threaded fasteners against shock and vibration while still allowing disassembly with standard hand tools. Two things separate it from 242: it cures reliably on passive substrates — stainless steel, plated surfaces — without an activator, and it tolerates oil, so light cutting, lubricating and anti-corrosion fluids on the threads do not stop it working.
Key features
- Oil tolerant — works through light cutting and anti-corrosion fluid
- Cures on passive substrates: stainless steel, plated surfaces
- Medium strength — 22 N·m breakaway on M10, hand-tool removable
- Thixotropic, so it does not migrate after application
- Glass transition temperature 100°C
- Holds 115% of initial strength after 1,000 h in motor oil at 125°C
Typical applications
- Oily fasteners
- Marine and workshop use
Technical data
Uncured material
| Technology | Acrylic |
| Chemical type | Dimethacrylate ester |
| Appearance | Blue |
| Fluorescence | Positive under UV light |
| Components | One component — no mixing |
| Cure | Anaerobic; secondary cure by activator |
| Viscosity | Medium, thixotropic |
| Viscosity, Brookfield RVT 25°C | Spindle 3 at 20 rpm: 1,300–3,000 mPa·s |
| Viscosity, cone & plate 25°C | 350 mPa·s at 129 s⁻¹ |
| Specific gravity at 25°C | 1.08 |
Torque by fastener size
Cured 24 hours at 23°C, unseated, ISO 10964.
| Fastener | Breakaway N·m (lb·in) | Prevail N·m (lb·in) |
|---|
| M6 black oxide bolts, mild steel nuts | 9 (80) | 1 (9) |
| M10 black oxide bolts, mild steel nuts | 22 (200) | 9 (80) |
| M16 black oxide bolts, mild steel nuts | 50 (440) | 20 (180) |
| 3/8 × 16 steel nuts and bolts | 12 (110) | 8 (70) |
Further torque and strength
| Breakloose torque, M10, pre-torqued to 5 N·m | 22 N·m (200 lb·in) |
| Prevail torque at 180°, M10, pre-torqued | 9 N·m (80 lb·in) |
| Compressive shear strength (ISO 10123) | >7.6 N/mm² (1,100 psi) |
| Breakloose after 1 week, M10 zinc phosphate | 30 N·m (270 lb·in) |
| Breakloose after 1 week, M10 stainless steel | 14 N·m (120 lb·in) |
Chemical resistance
M10 zinc phosphate nuts and bolts, breakloose torque as a percentage of initial strength.
| Environment | °C | 500 h | 1,000 h | 5,000 h |
|---|
| Motor oil | 125 | 110% | 115% | 115% |
| Unleaded petrol | 23 | 100% | 95% | 100% |
| Brake fluid | 23 | 105% | 110% | 125% |
| Water / glycol 50:50 | 87 | 120% | 125% | 130% |
| Acetone | 23 | 85% | 85% | 80% |
| Ethanol | 23 | 95% | 90% | 90% |
| B100 bio-diesel | 23 | 110% | 110% | 125% |
| DEF (AdBlue®) | 23 | 61% | 59% | 70% |
Cured material
| Glass transition temperature (ISO 11359-2) | 100°C |
| Coefficient of thermal expansion, below Tg | 80 × 10⁻⁶ K⁻¹ |
| Coefficient of thermal expansion, above Tg | 90 × 10⁻⁶ K⁻¹ |
| Thermal conductivity (ISO 8302) | 0.1 W/(m·K) |
| Specific heat | 0.3 kJ/(kg·K) |
| Cold strength | Tested to −75°C |
How to use it
- Clean all threads, internal and external, with a Loctite cleaning solvent and allow to dry.
- Shake the bottle thoroughly before use.
- Do not let the nozzle touch metal — it makes the product cure in the tip.
- Thru holes: apply several drops onto the bolt at the nut engagement area.
- Blind holes: apply several drops down the internal threads to the bottom of the hole.
- Sealing: apply a 360° bead to the leading male threads, leaving the first thread free, and work it into the thread roots.
- Assemble and tighten to the specified torque within the fixture time.
Handling and storage
- Not recommended for pure oxygen or oxygen-rich systems.
- Not a sealant for chlorine or other strong oxidising materials.
- Not normally recommended on plastics — thermoplastics can stress-crack.
- On passive metals (stainless, aluminium, plated) or below 5°C, use Loctite SF 7471 or SF 7649 activator to bring the cure speed up.
- Store unopened and dry. Henkel gives optimal storage as 8°C to 21°C; outside 8–28°C the product properties can be affected.
- Do not return decanted product to the original container.
Choosing between the threadlocker grades
243 is the default for fasteners M6 and above that will be serviced normally. Drop to 222 on small or long-engagement screws that would strip before the adhesive released. Step up to 270 where the joint must not come apart without heat, or 277 for bolts and studs M25 and larger.
Always read the current technical and safety data before use —
ask us and we'll send it with your quotation.
