Last Updated: Dec 14, 2022     Views: 23252

Example of uranium glass. Image: Covered Sugar Bowl. Made in England between 1840 and 1860. Gift of Mrs. Alan Cornwell. CMoG 66.2.3.

Hello! Thank you for your question. Here's an answer from Dr. Robert Brill, Research Scientist Emeritus:

There are several elements that will cause common glasses to fluoresce. The fluorescent response depends on several factors: primarily the elements present, sometimes matrix effects, the concentrations, the wavelength of the exciting radiation, the intensity of the exciting radiation, possibly the redox [reduction-oxidation] state of the elements, colorants that might be present, etc.

Leaving out the exotic elements not found in ordinary glasses, the responses are more-or-less as follows:

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 a lead matrix. You can tell a uranium-containing glass just by looking at it. Once you have seen the color, you will remember it. The color is usually obtained by adding ~0.5 % U2O3. Ancient glasses contain at most a few ppm of U -- not nearly enough to cause any UV fluorescence.

Pb (Lead) -- A strong icy-blue response, 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%. Pb normally fluoresces more strongly than manganese or antimony. (Don't mistake the reflection of visible purple light from the UV lamp for Pb fluorescence. The Pb fluorescence is an icy-blue color and emanates from within the body of the glass.)

Mn (Manganese) -- A moderately strong "lemonade-like" greenish-yellow, often somewhat turbid. This is usually not at all a strong fluorescence. Mn usually requires a level of ~ 0.5% (?) to be readily visible. The greenish-yellow might be absorbed by the purple color of the body of the glass itself. (Oxidized Mn is a purple colorant.)

Sb (Antimony) -- A bluish, whitish often rather weak fluorescence. It may be obscured by other fluorescent species or colorants.

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Comments (4)

  1. What is the u-v wavelength that excites fostoria American 2056? I bought 3 different u-v lights which all produced very little yellow glow. 20 years ago I borrowed an old u-v Light which made my small collection glow quite brightly. Thank you
    by Tom on Sep 23, 2018
  2. To answer your question, I would need to know the wavelength...nm...of the lights you purchased. That way I have a better chance of giving you a correct answer. If you already have an answer, please let me know!
    by Mike on Apr 24, 2021
  3. You forgot to add Soda Lime Glass, made using calcium carbonate in the batch, which can produce a light yellowish or light greenish color when exposed to a black light. Sometimes it glows red when used in some colored glass, most often red and is often mistaken for their being cadmium used in the glass batch.
    by John on Jan 12, 2022
  4. Hi - Just curious why high-lead glasses are usually colorless (mentioned in the text). This is in the context of lower Pb% showing as blue. Many thanks in advance
    by Adam on Jan 28, 2023

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