Loctite Klean 'N Prime Anaerobic Activator Spray — 4.5 oz aerosol, speeds cure on passive metals and in cold

Loctite 37509 Klean 'N Prime Activator is an aerosol primer that prepares inactive or passive metal surfaces so anaerobic adhesives, threadlockers, and sealants cure faster and bond stronger—even in cold conditions.

This 4.5 oz spray is formulated to improve adhesion on plated parts and metals that normally resist anaerobic cure, such as stainless steel, aluminum, gold, and silver. Technicians and DIYers use it where threads, fasteners, and housings require reliable sealing or locking but the substrate is inert or the job happens at low temperatures. It accelerates cure times for anaerobic products and broadens compatibility so assemblies from small fasteners to larger housings secure reliably.

How does this activator help with inactive metal surfaces?

Many metals have passive films that slow or prevent anaerobic adhesives from polymerizing. The activator conditions the substrate by altering the surface chemistry so the adhesive can initiate and finish its cure. This is especially useful for plated parts, precious metals, and alloys with protective oxides.

• Promotes adhesion on plated parts, stainless steel, aluminum, gold and silver.
• Allows anaerobic products to cure where they otherwise would not.
• Useful for plated fasteners and decorative metal components.

Will it speed up cure times in cold environments?

Yes—this activator is designed to improve the cure rate of anaerobic adhesives and sealers at temperatures below 41°F (5°C). It helps maintain consistent performance when jobs must be completed in colder shops or outdoors.

• Reduces cure time for threadlockers and gasketing compounds.
• Reliable performance in low-temperature applications down to or below 41°F (5°C).
• Good for winter maintenance or chilled storage areas.

What parts and applications are appropriate for this product?

The activator is versatile across automotive and industrial uses—ideal for areas where passive metals meet adhesives. It’s commonly used around engine components, housings, and threaded assemblies that must stay sealed or locked during operation.

• Automotive: valve covers, oil pans, intake manifolds, alternators, distributor clamps.
• Fasteners and small gaps: works on screws and bolts from 0.08” to 0.5” (2.2–12 mm).
• Other: air conditioning belt assemblies, carburetor screws, hairline crack sealing.

How do I use the aerosol for best results?

Apply the activator sparingly and allow a brief flash period before applying the anaerobic adhesive or sealant. Surface cleanliness is key—remove oil, dirt, and loose debris first to maximize contact. Follow adhesive manufacturer cure recommendations once the activator-treated surface is ready.

• Clean surfaces of oil, grease, and particulates before spraying.
• Apply a thin, even coat of activator; wait a few seconds to flash off.
• Apply anaerobic adhesive or sealant and assemble according to product instructions.

Who is this for? Loctite 37509 Klean 'N Prime Activator is aimed at professional mechanics, maintenance technicians, and serious DIYers who work with plated or passive metals and need dependable anaerobic bonding in challenging conditions. It’s suited to shops and fieldwork where low temperatures, inert surfaces, or delicate metal finishes would otherwise impede adhesive performance. If you frequently assemble threaded components, seal housings, or repair small cracks on inactive substrates, this activator helps ensure consistent, stronger cures for a wide range of anaerobic products.