Overview & Benefits
Loctite Grade B (Letter Grade B / 085) is a medium-strength, medium-viscosity, yellow anaerobic threadlocker based on acrylic dimethacrylate ester chemistry. It cures in the absence of air and in contact with metal to form a tough, thermoset plastic that locks and seals threads.
Originally developed in the 1950s, it remains a trusted choice for fine threaded fasteners that need secure locking under vibration but still must be removable with standard hand tools for maintenance.
Why choose Loctite Grade B?
1) Medium strength you can still service
Grade B provides strong resistance to loosening while still allowing fasteners to be disassembled with normal tools, making it ideal for equipment that will be serviced or adjusted over its life.
2) Optimized for fine threaded hardware
The product is specified for fine threaded nuts, bolts and studs, where its medium viscosity wets the flank of the thread and fills the small clearances typical of fine-pitch fasteners.
3) Dual-use: threadlocking and bearing mounting
Beyond locking nuts and bolts, Loctite Grade B is also used for mounting bearings, bushings and other shaft-related parts, helping prevent micro-movement and fretting between mating surfaces.
4) Proven performance to military standards
Grade B is tested to the lot requirements of MIL-S-22473E (Grade B) and referenced in ASTM D5363 classifications, giving engineers confidence in repeatable performance for legacy and aerospace-related designs.
5) Easy QC with UV fluorescence
The uncured product is fluorescent under UV light, so production and maintenance teams can quickly verify that threadlocker has been applied to the fastener or joint.
Typical Applications
Threadlocking
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Fine threaded nuts, bolts and studs on pumps, motors and gearboxes
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Instrumentation and controls where serviceability is required
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Fasteners on light machinery, fixtures and general industrial assemblies
Bearing and shaft components
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Mounting bearings on shafts or in housings
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Securing bushings, sleeves and collars against rotation or creep
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Other shaft-related assemblies where micro-movement must be controlled
Best suited for metal-to-metal joints where you want strong vibration resistance and sealing, but still need the option to disassemble with tools.
How to Use Loctite Grade B
Step 1 – Clean the joint
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Remove loose rust, dirt, old threadlocker and heavy grease from threads.
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Light preservative oil is usually acceptable, but heavily oiled parts should be wiped or solvent-cleaned for best performance.
Step 2 – Apply the product
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Shake the bottle briefly.
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Apply a continuous bead of Grade B to the male thread, covering the full engagement length.
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For blind holes, apply some product into the female threads as well, so adhesive is pushed through the entire contact area as the fastener is installed.
Step 3 – Assemble and tighten
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Assemble the parts and torque the fastener to the specified value.
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Avoid disturbing the joint during the first few minutes while the adhesive begins to fixture.
Step 4 – Allow to cure
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The assembly typically reaches handling strength within a short time, but plan for up to 24 hours at room temperature for full development of properties (longer at low temperatures or with passive metals).
Step 5 – Disassembly (if needed)
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Loosen with standard hand tools.
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For very large or highly loaded fasteners, extra lever arm or gradual breakaway torque may be needed, but Grade B is still intended to be removable.
Safety & Handling
Based on typical SDS information for Loctite 085 / Grade B:
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Avoid skin and eye contact; may cause irritation or sensitization in susceptible individuals.
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Use in a well-ventilated area; avoid breathing vapors.
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Wear safety glasses and protective gloves when dispensing.
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Do not discharge uncured product into drains or the environment.
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Store in a cool, dry place in the original, tightly closed container, away from heat and direct sunlight.
Always consult the current SDS for your region before use.
FAQs
Q1: How is Loctite Grade B different from blue threadlockers like Loctite 243?
Loctite Grade B is a yellow, medium-strength letter-grade product originally qualified to MIL-S-22473E. It is optimized for fine threads and often used where legacy specifications call for Grade B. Loctite 243 is a modern blue, oil-tolerant medium-strength threadlocker aimed at a broader range of thread sizes and substrates.
Q2: What thread sizes are best for Grade B?
Grade B is typically chosen for fine threaded nuts, bolts and studs found on small to medium mechanical assemblies, instruments and shaft components. On very large coarse threads, engineers often select other grades (e.g., letter Grade AV) specifically formulated for large hardware.
Q3: Can I use Loctite Grade B to mount bearings and bushings?
Yes. One common use of Grade B is mounting bearings, bushings and other shaft-related parts, where it helps prevent fretting and loosening under vibration while still allowing future disassembly with appropriate tools.
Q4: Is Grade B removable?
Yes. It is classified as medium strength, so fasteners locked with Grade B can typically be removed with ordinary hand tools. If you need “permanent” locking that usually requires heat or high breakaway torque, a high-strength red grade (e.g., Grade AV) is more appropriate.
Q5: Does Loctite Grade B work on stainless steel or plated fasteners?
Loctite Grade B will cure on passive metals such as stainless steel and plated parts, but cure may be slower than on plain carbon steel. Allow extra time for full strength, or consult Henkel about using a primer/activator if rapid cure is critical.
Q6: Can I use Grade B on plastic threads?
No. Grade B is designed for metal-to-metal assemblies. Anaerobic threadlockers can cause stress cracking in some plastics and do not cure properly on non-metallic threads. For plastic or mixed joints, choose a plastic-compatible adhesive or sealant.
Q7: How should I store the product to maintain shelf life?
Keep bottles closed when not in use, store at moderate temperatures away from heat sources and sunlight, and avoid contaminating the bottle by touching the nozzle to metal parts. Follow Henkel’s shelf-life guidance printed on the label and in the TDS/SDS.
