Reference
Loctite Selector Guide — Thread-Lockers, Retaining Compounds & Sealants
Loctite ships dozens of anaerobic adhesives, and picking the wrong one is the fastest way to strip a bolt or seize a bearing on a shaft. This guide is the shortlist we hand to MRO teams: the numbers that actually cover 90% of industrial use, sorted by job.
Thread-lockers (purple / blue / red / green)
| Loctite | Color | Strength | Best for | Size range | Temp |
|---|---|---|---|---|---|
| 222 | Purple | Low | Small screws under 1/4", low-vibration adjustment screws, calibration hardware | Up to 1/4" (M6) | -65 to 300°F |
| 242 | Blue | Medium | General-purpose thread-locking, allows removal with hand tools | 1/4" – 3/4" (M6 – M20) | -65 to 300°F |
| 243 | Blue | Medium | Oil-tolerant version of 242 — works on lightly oiled fasteners without cleaning | 1/4" – 3/4" (M6 – M20) | -65 to 360°F |
| 262 | Red | High | Permanent locking on studs and larger bolts; heavy vibration | 3/8" – 3/4" (M10 – M20) | -65 to 360°F |
| 271 | Red | High | Permanent locking of studs, plugs and bolts up to 1" | Up to 1" (M25) | -65 to 300°F |
| 272 | Red | High + heat | High-temperature red — same as 271 up to 450°F | Up to 1" (M25) | -65 to 450°F |
| 277 | Red | High | Permanent locking for very large fasteners over 3/4" | 3/4" – 1-1/2" (M20 – M40) | -65 to 300°F |
| 290 | Green | Wicking | Wicks into pre-assembled fasteners; sealing and locking of set screws, headless bolts | Any pre-assembled | -65 to 300°F |
Retaining compounds — bearings, bushings, keys
| Loctite | Color | Strength | Best for | Size range | Temp |
|---|---|---|---|---|---|
| 603 | Green | High | Oil-tolerant retaining compound for slip/press-fit cylindrical assemblies | Gap up to 0.005" | -65 to 300°F |
| 609 | Green | General | General-purpose retaining, keys/keyways, bushings | Gap up to 0.005" | -65 to 300°F |
| 620 | Green | High-temp | Heat-resistant retaining compound for bearings on shafts in hot service | Gap up to 0.015" | -65 to 450°F |
| 638 | Green | Max | Maximum-strength retainer for slip-fit or worn parts; large gaps | Gap up to 0.010" | -65 to 300°F |
| 660 | Silver | Repair | Repair of worn shafts, keyways, splines; fills large gaps | Gap up to 0.020" | -65 to 300°F |
| 680 | Green | High + gap | Slip/press-fit cylindrical assemblies with larger diametric clearances | Gap up to 0.015" | -65 to 300°F |
Thread sealants — pipe fittings, hydraulic, pneumatic
| Loctite | Color | Strength | Best for | Size range | Temp |
|---|---|---|---|---|---|
| 545 | Purple | Low pressure | Hydraulic and pneumatic thread sealant for fine threads | Up to 3/4" | -65 to 300°F |
| 565 | White | General | Controlled-strength thread sealant for stainless & coated fittings | Up to 2" | -65 to 300°F |
| 567 | White | High-temp | PTFE-filled sealant for tapered pipe threads on stainless & coated fittings | Up to 3" | -65 to 400°F |
| 592 | White | Slow cure | Slow-cure thread sealant giving longer working time on large fittings | Up to 3" | -65 to 400°F |
Quick decision rules
242 vs 243: both are medium-strength blue. Use 243 if the fastener is oily and you can't clean it; otherwise 242. 243 also has a wider substrate tolerance and slightly higher temp rating.
271 vs 272: both are high-strength red. Pick 272 if the joint sees temperatures above 300°F (steam, exhaust, motor housings). Otherwise 271 is the default red.
Retainer selection: choose by diametric gap. Under 0.005" use 603 / 609; up to 0.010" use 638; up to 0.015" use 680; larger gaps or worn shafts use 660.
Pipe sealant: for stainless or coated fittings use 567 (PTFE-filled, high-temp). For general steel pipework 545 handles hydraulics and pneumatics up to 3/4" fittings.