How To Identify Uranium Glass

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Glass that contains uranium is often called uranium glass. It has a yellow or greenish color, and it glows under blacklight. But how can you tell if a piece of glass is uranium glass?

There are two ways to determine if a piece of glass contains uranium. The first is to hold it up to a UV or blacklight. If the glass glows, then it has uranium in it. The second way is to test the glass with a Geiger counter to see if radioactivity is present.

Let’s take a closer look at how you can identify uranium glass with and without a blacklight as well as the difference between uranium glass and vaseline glass, which also glows. That way, if you’re lucky enough to find some uranium glass in a thrift store, you’ll be able to tell if it’s the real thing.

What Is Uranium Glass?

UV light passes through a block of uranium glass

Uranium glass is a type of lead glass that contains uranium dioxide. The addition of uranium dioxide makes the glass luminescent, meaning it will glow in the dark. This trait makes uranium glass perfect for making items such as bowls, vases, and jewelry.

Uranium glass was first made in the early 1830s and quickly became popular for its beauty and uniqueness. It was used in everything from jewelry to tableware. Some companies even made uranium glass radio dials because the uranium made the dial glow in the dark.

Production of uranium glass decreased during World War II because uranium was directed toward the war effort. However, it has seen a resurgence in recent years as people have become interested in collecting vintage uranium glass items.

What’s the Difference Between Uranium Glass and Vaseline Glass?

Both uranium and Vaseline glass contain uranium oxide, making them glow under a blacklight.

Vaseline glass is a type of uranium glass that is transparent, with a greasy yellow-green color and a sheen similar to Vaseline. It is also called ‘canary glass’ or ‘Depression glass.’

Uranium glass, meanwhile, is a more general term to describe any type of glass that contain small amounts of uranium oxide. It can be opaque or transparent and is often found in green, yellow, and pink.

How Do You Identify Uranium Glass?

Glowing Uranium Glass

If you’re lucky enough to find a piece of uranium glass, here are a few tips on how to identify it:

Look for a Fluorescent Quality

One of the easiest ways to identify uranium glass is to look for its fluorescent quality. When exposed to ultraviolet light, uranium glass will often glow brightly.

A blacklight, like this UV flashlight (on Amazon), is the best way to test for this quality. Hold the glass to the light and look for a bright, fluorescent glow.

Check for a Yellow or Green Tint

Another way to identify uranium glass is to check for a yellow or green tint. Uranium glass typically has a slightly yellow or greenish color to it, although this can vary depending on the exact composition of the glass.

However, not all yellow or green glass is uranium, so this is just one indicator to consider.

Check for Radioactive Properties

Uranium glass is somewhat radioactive, although the amount of radioactivity is low and isn’t considered harmful to humans. One way to check whether a piece of glass is radioactive is to use a Geiger counter, like this one from VISLONE (on Amazon).

To use a Geiger counter on uranium glass, hold the sensor close to the glass and wait for a reading. The reading should be higher than normal background radiation levels if the glass is uranium.

Look for Opalescence

Opalescence is another common characteristic of uranium glass. Opalescence is a type of iridescence that causes the surface of the glass to appear to change color when viewed from different angles.

If you hold uranium glass up to the light, you may see a rainbow of colors on the surface of the glass.

Check for a Date Stamp

Uranium glass began production in the late 1800s, so if a piece of glass has a date stamp, check to see if it’s from this time period. If it is, there’s a good chance that the glass is uranium.

Look for Manufacturer Markings

Fenton Art Glass Company, Mosser Glass, and Westmoreland Specialty Glass Company are the names of three companies that produced a large quantity of uranium glass. If you find a piece of glass stamped with their brand, you’ve likely found a uranium glass.

You can often find maker marks on the bottom of glassware. If you’re having trouble finding any markings, try holding the piece up to the light. The marks will usually be embossed or raised, making it easier to see when the light shines through.

How to Identify Uranium Glass Without a Blacklight

The only way to be sure that a piece of glass contains uranium without a blacklight is to have it tested in a laboratory.

You can look for things that suggest that a piece of glass contains uranium, but none are fool-proof. For this reason, if you’re unsure, you’ll want to confirm with a blacklight or Geiger counter test.

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