Half-life is a term used to describe the time required for a quantity to reduce half of its value, and the term is commonly used in nuclear physics to define radioactive decay.
Several years ago, my friend Elizabeth, knowing that I am fascinated with glass objects, introduced me to an interesting vase. The type of glass used to make this object is called uranium glass, because a small amount of uranium, typically in the form of an oxide, is added to the glass mix before melting. The uranium gives the glass a pale yellowish-green colouration. In the 1920s this colour led to the nickname Vaseline glass because it resembled the colour of petroleum jelly from that time.
Uranium glass is a subset of a type of glass called Depression Era Glass. Depression Era Glass, or simply Depression Glass, was popular and inexpensive during the depression period and was made into common houseware articles such as vases, cups, saucers, plates, and candy bowls. Using a sensitive Geiger counter, uranium glass would register slightly higher than normal background radiation. Most pieces of this type of glass are harmless and only slightly radioactive. When asked if ingesting uranium glass would cause radioactive poisoning, one scientist replied that the shards of glass would kill you before your body even noticed the radiation.
All very interesting – but what fascinated me was the way that the uranium in the glass fluoresces under ultraviolet light. With that bit of knowledge, Elizabeth and I, with portable UV lights in hand, haunted the antique shops in the Ottawa area looking for reasonably priced uranium glass objects. In addition to Elizabeth’s vase, we discovered a small plate, a cup and saucer, an ice cream dish and a candy bowl. I found several inexpensive UV fluorescent lights and after some experimentation, I started taking photos using the light from the fluorescing glass. Using some paints and dyes, which phosphoresces under UV light, I added some painted objects to the glass scenes.
These photos are the result of that experimentation.
I took these two photos as a comparison of a hand-painted dried rose under normal light and UV light.