Loctite Prism 420 Clear Ultra-Low_Viscosity Wicking (2cP Water-Like) Instant CA Adhesive-General Purpose (40640)

Product Name: Loctite Prism 420 Ultra-Low Viscosity Instant CA Adhesive (Wicking Grade)

Loctite Prism 420 is a specialized ultra-low viscosity ethyl cyanoacrylate adhesive. With a viscosity of just 2 cP, it is water-thin, allowing it to penetrate tight cracks and pre-assembled parts via capillary action. It is a general-purpose instant adhesive suitable for bonding metals, plastics, and rubbers where very fast fixturing and wicking capability are required. It is ideal for post-assembly bonding where the adhesive must flow into the joint *after* the parts are already together.

Popular Applications & Uses
- Wicking into pre-assembled parts to lock them in place (e.g., locking pins, keys, or set screws).
- Bonding closely fitted parts where gap filling is not required.
- Repairing hairline cracks in housings or components.
- Rapid assembly of small metal or plastic parts.
- Tamper-proofing adjustment screws.

Industries that Commonly Use It
- Electronics (Locking components, wire tacking)
- General Industrial Manufacturing
- Medical Device Assembly
- Automotive
- Appliance Repair

Special and Unique Features
- Ultra-Low Viscosity: At ~2 cP, it is thinner than standard "Super Glue" and flows like water.
- Wicking / Capillary Action: Designed to penetrate pre-assembled joints.
- High Speed: Fixtures in 5-20 seconds on most materials.
- General Purpose: Bonds a wide range of substrates (metals, plastics, rubbers).
- Mil-Spec Compliant: Meets Commercial Item Description A-A-3097 (formerly Mil-A-46050C).

Key Properties
- Base: Ethyl Cyanoacrylate
- Color: Clear / Colorless
- Viscosity: Ultra-Low (~2 cP)
- Specific Gravity: 1.05
- Temperature Range: -65°F to 180°F (-54°C to 82°C) - *Check TDS for specific high-temp ratings if reformulated.*
- Shear Strength: ~2,200 - 3,000 psi (Steel)

Materials Bonded
- Metals (Steel, Aluminum, etc.)
- Plastics (ABS, PVC, Polycarbonate, Phenolic)
- Rubber (Nitrile, Neoprene)

Cure Information
- Fixture Time: 5 - 20 seconds.
- Full Cure: 24 hours.
- Cure Mechanism: Moisture cure.

Known backups / known substitutes for this product
- Loctite 406 (Also ultra-low viscosity, but optimized for plastics/rubbers).
- Permatex Penetrating Grade Super Glue.
- 3M Scotch-Weld CA4.
- Vibra-Tite 306.

Comparison Note
- **Loctite 420 vs. 406:** Both are ultra-low viscosity (wicking) adhesives. **406** is optimized for **plastics and rubbers**, often providing higher strength on difficult-to-bond plastics. **420** is a **general purpose** adhesive that performs slightly better on **metals** and mixed assemblies. If you are bonding metal parts or a mix of metal/plastic, 420 is often the preferred choice.
- **Loctite 420 vs. 401:** **420** is water-thin (2 cP) for wicking. **401** is medium viscosity (~100 cP) for gap filling and porous surfaces. Use 420 for tight, pre-assembled joints; use 401 for general bonding where gaps exist.