Product details
| Grade | Loctite 680 |
| Strength | High strength |
| Colour | Green |
| Family | Retaining compounds |
| 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 680 is for
A high-strength retaining compound with an unusual property: it is stronger on stainless steel than on mild steel — 28 N/mm² against 26. It cures on passive substrates and plated surfaces without activation, tolerates cutting and anti-corrosion oils, and reaches ≥24.1 N/mm² in one hour at 93°C, which suits it to heated assembly work. It also carries NSF 61 certification for potable water systems.
Key features
- Stronger on stainless (28 N/mm²) than on mild steel (26 N/mm²)
- ≥24.1 N/mm² after just one hour at 93°C
- Cures on stainless and plated surfaces; tolerates light oil contamination
- Certified to ANSI/NSF Standard 61 for potable water to 82°C (a regional approval)
- Gaps to 0.25 mm; cure graphs published at 0.05, 0.15 and 0.25 mm
- Gains strength in service — 160% in motor oil, 135% in water/glycol
- Heat ageing data to 200°C; cold strength tested to −75°C
- Low thermal expansion at 52 × 10⁻⁶ K⁻¹
Technical data
Uncured material
| Technology | Acrylic |
| Chemical type | Methacrylate ester |
| Appearance | Green liquid |
| Fluorescence | Positive under UV light |
| Components | One component — no mixing |
| Cure | Anaerobic; secondary cure by activator |
| Viscosity, Brookfield RVT 25°C | Spindle 3 at 20 rpm: 750–1,750 mPa·s |
| Viscosity, cone & plate 25°C | 650–1,850 mPa·s at 129 s⁻¹ |
| Viscosity class | Medium |
| Specific gravity at 25°C | 1.1 |
Compressive shear strength (ISO 10123)
| Substrate and cure | N/mm² (psi) |
|---|
| Steel, 1 hour at 93°C | ≥24.1 (3,500) |
| Steel, 24 hours at 22°C | ≥19.3 (2,800) |
| Steel, 7 days at 22°C | 26 (3,740) |
| Stainless steel, 7 days at 22°C | 28 (4,030) |
| Aluminium, 7 days at 22°C | 16 (2,280) |
Torque performance
Cured 24 hours at 22°C, ISO 10964.
| Fastener | Breakaway / breakloose N·m (lb·in) | Prevail N·m (lb·in) |
|---|
| M10 black oxide bolts, mild steel nuts | 35 (315) | 28 (250) |
| 3/8 × 16 steel nuts and bolts | 17 (150) | — |
| M10 zinc phosphate, pre-torqued to 5 N·m | 30 (270) | 21 (190) |
| M10 stainless steel, pre-torqued to 5 N·m | 19 (165) | 21 (185) |
Chemical resistance
As a percentage of initial strength after ageing.
| Environment | °C | 100 h | 500 h | 1,000 h |
|---|
| Motor oil (5W40 synthetic) | 125 | 135% | 160% | 145% |
| Water / glycol 50:50 | 87 | 115% | 135% | 135% |
| Unleaded petrol | 22 | 85% | 95% | 110% |
| Brake fluid | 22 | 85% | 100% | 110% |
| B100 bio-diesel | 22 | 90% | 110% | 110% |
| DEF (AdBlue®) | 22 | 95% | 105% | 110% |
| E85 ethanol fuel | 22 | 85% | 105% | 105% |
| Sodium hydroxide 20% | 22 | 90% | 90% | 90% |
| Phosphoric acid 10% | 22 | 85% | 75% | 80% |
Cured material
| Coefficient of thermal expansion (ISO 11359-2) | 52 × 10⁻⁶ K⁻¹ |
| Heat ageing data published at | 120°C, 150°C, 180°C and 200°C |
| Cold strength | Tested to −75°C |
How to use it
- Clean all surfaces, external and internal, with a Loctite cleaning solvent and allow to dry.
- On inactive metals, or where large gaps are present, use an activator and allow to dry.
- Slip fits: apply around the leading edge of the male part and the inside of the female part, and use a rotating motion during assembly to spread it.
- Press fits: apply thoroughly to both surfaces and assemble at high press-on rates.
- Shrink fits: coat to a smooth even film. Heating the female part — coat the male. Cooling the male part — coat the female. Doing both — apply to the cooled part, and avoid condensation on it.
- Do not disturb the parts until handling strength is reached.
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.
- Disassembly: hand tools first; if needed apply localised heat to about 250°C and take apart while hot. If that temperature is not possible, heat as far as you can and use mechanical aids.
- Store unopened and dry, ideally 8°C to 21°C; outside 8–28°C the properties can be affected.
- Do not return decanted product to the original container.
Loctite 680 or 648?
Both are oil-tolerant grades that cure on stainless. 648 is thinner (500 vs 750–1,750 mPa·s) and stronger on steel at 31 N/mm², and is the grade Henkel names for shrink fits. 680 is slightly thicker, marginally stronger on stainless at 28 N/mm², and carries NSF 61 potable water certification — which decides it for water system work. For a worn fit beyond 0.25 mm, neither applies: use 660.
Always read the current technical and safety data before use —
ask us and we'll send it with your quotation.
