Two of the most common single-part industrial adhesives cure by completely different triggers. UV adhesive hardens under ultraviolet or visible light in seconds, while anaerobic adhesive sets only where air is excluded and metal is present. Matching the chemistry to the joint is what determines whether a bond survives service. How UV Adhesive Cures UV adhesive, also called light-cure adhesive, relies on photoinitiators that fragment when they absorb light in a specific band, typically 365 to 405 nanometers. Those fragments start a chain reaction that converts the liquid resin to a solid network. Fixture time is often under five seconds at surface intensities of 50 to 200 milliwatts per square centimeter, and full cure follows within a minute. Because the reaction needs light to reach the resin, at least one substrate must transmit UV or the bond line must sit at an exposed edge. Glass, clear polycarbonate, and acrylic are ideal. Opaque assemblies need a secondary cure mechanism or a redesigned joint. For transparent work, the tradeoffs are covered in our guide on UV glue versus epoxy for transparent bonding. How Anaerobic Adhesive Cures Anaerobic adhesive stays liquid while it contacts oxygen. Once it is confined between two close-fitting metal surfaces, the oxygen is displaced and metal ions catalyze polymerization. Common uses are threadlocking, retaining cylindrical parts, and forming in-place gaskets on machined flanges. Cure speed depends on the metal. Active substrates such as steel, brass, and copper reach handling strength in 10 to 30 minutes. Inactive or plated surfaces like stainless steel, aluminum, and zinc can take several hours or need a primer. Full strength typically develops over 24 hours at room temperature. Curing Speed and Process Control UV adhesive gives near-instant, on-demand cure. Production lines can index parts through a curing station and move directly to the next operation, which suits high-volume assembly. Dose uniformity matters, and lamp output drift is a frequent source of weak bonds, as explained in our overview of UV light guide degradation over time. Anaerobic adhesive cannot be rushed the same way. Its slow, dark cure is an advantage for parts that must be positioned and torqued before the bond locks, but it adds work-in-process time and requires clean, oil-free metal. Bond Strength and Substrate Fit UV adhesives develop shear strengths from about 1,500 to over 4,000 psi on glass and metal, with good resistance to humidity and thermal cycling once fully cured. They excel at thin bond lines on rigid, non-porous parts. Anaerobic adhesives are formulated by strength grade. Low-strength threadlockers allow hand removal, medium grades resist vibration loosening, and high-strength grades are close to permanent. They fill the clearance in threaded and slip-fit joints, resist mechanical shock, and tolerate oils and coolants after cure. For structural metal joints under sustained load, a two-part epoxy often outperforms both. See our comparison of UV glue versus epoxy for heavy-duty repairs. Environmental and Handling Considerations UV adhesives are 100 percent solids and release no solvents during cure, which simplifies ventilation requirements. Uncured resin should…