Which UV source is commonly used to accelerate paint drying in finishing processes?

• A. High and Low Pressure Mercury Discharge Lamps
• B. Sunlight
• C. Plasma Torches
• D. Incandescent Lamps

Answer: (A)

Ultraviolet curing relies on photoinitiators in coatings that generate reactive species when struck by UV light, causing rapid polymerization and a hard, dry film in a short time. The most common industrial source for this process is mercury discharge lamps, both high- and low-pressure types. They produce a strong, broad UV emission that efficiently activates typical photoinitiators used in paints and coatings, delivering fast, controlled curing on production lines. Sunlight is unreliable for finishing processes because its intensity and spectrum vary with time and weather, making it difficult to achieve consistent curing. Plasma torches mainly provide heat and are not suited for initiating photopolymerization, and incandescent lamps emit mostly visible light with little UV, so they don’t effectively accelerate UV curing. For these reasons, mercury discharge lamps are the standard choice.