Q. Which ingredients cause glass to fluoresce?

There are several elements that will cause common glasses to fluoresce. The fluorescent response depends on several factors, including:

• the elements present
• the concentrations 
• the wavelength of the exciting radiation 
• the intensity of the exciting radiation 
• possibly the reduction-oxidation state of the elements

Some common elements found in glasses that cause fluorescence are:

• U (Uranium)
  • A very strong bright-green response
  • The color of the glass itself in visible light is usually a bright yellow or yellowish-green, or an amber color in lead glasses
  • The color is usually obtained by adding ~0.5 % U2O3
• Pb (Lead) 
  • A strong icy-blue response
    • Pb normally fluoresces more strongly than manganese or antimony but not normally as strong as U
  • The fluorescence is visible under both long-wave and short-wave UV
  • High-lead glasses are usually colorless
  • The fluorescence becomes noticeable at a level of about 5%, and is strong by about 10-15%
• Mn (Manganese)
  • A "lemonade-like" greenish-yellow. This is usually not at all a strong fluorescence
    • The greenish-yellow might be absorbed by the purple color of the body of the glass itself
  • Mn usually requires a level of ~ 0.5% to be readily visible
• Sb (Antimony)
  • A bluish, whitish often rather weak fluorescence
    • It may be obscured by other fluorescent colorants

Don't mistake the reflection of visible purple light from the UV lamp for fluorescence.

Rare earth metals and less common ingredients may also cause glass to fluoresce. 

Please don't hesitate to contact us with your glass-related questions in the future!