UV reactive glass – glass that glows under a “black light” – has become very popular in recent years, commanding premium prices in online sales and auctions. UV reactive glass cats are no exception – these “glowies” have acquired a fan club all their own!
What makes them glow? Glass Additives 101
Glass that glows does so because of certain substances added to the glass. The original intent was not to make it glow, but to either enhance the color or the improve the color stability of the finished glass items.
Some of the common additives:
Uranium oxide
Uranium oxide is depleted uranium. It gives the finished glass a slightly greenish tint in sunlight and glows bright green under a black light.
While some older uranium glass emits concerningly high levels of radioactivity, contemporary glassware contains quite a bit less uranium and is generally considered safe.
Some types of glass that contain uranium:
- Vaseline (clear yellow to greenish yellow)
- Custard Glass (opaque off-white)
- Burmese Glass (Custard glass shading to another color, like blue or pink.)
Manganese
Often added to purple glass,to keep it from changing color with exposure to sunlight. It typically glows light green but can glow from green to red or shades of orange
Cadmium – found mainly in red and orange glass, it glows bright yellow or orange to red or pink.
Selenium – found in newer glass (red, yellow), glows pale orange or pink.
UV Reactivity in Mosser Sitting Cats
UV color(s) and color names of known Mosser cats that glow. Unless noted otherwise, variations of these colors (satin, iridized, opalescent, slag) react the same way.
Bright Green (Uranium)
- Vaseline and variations (vaseline opal, vaseline satin)
- Slags with a vaseline base color (Tiger eye, Moonglo…)
- Custard glass and variations (custard, custard satin, green banana, brown banana, French vanilla)
- Slags with a custard base color (cameo bronze)
- Slags with custard glass slag (custard grape, Kashmir green)
- Sea Breeze
- Twilight
- Autumn (slag) may contain some uranium
- Milk iridized (old – Pearl??)
- Dark amber (name?)
Red and orange (cadmium or selenium)
- Red, calico, autumn, flame
- Black magic (bright red)
- Rubina
- Pumpkin, candy corn
- Wine
- Black cherry (feet)
- Blazer / Harvest
- Fiesta
- Clay
- Red slag (red calico)
- Strawberry, Strawberry slag
- Tomato
- Marigold
Bright Yellow (Cadmium)
- Golden opalene
- Buttercup
Pale or Dull Green (probably manganese)
- Amethyst and variations (amethyst satin, amethyst iridized)
- Jasmine and jasmine satin
- Heirloom pink
- Aqua and variations (aqua opal, aqua satin, aqua iridized)
- Plum (sugar plum)
- Some crystal
- Apple green
- Blue
- Violet or Lavender Ice?
Colors that do NOT glow:
- Milk and variations
- Teal and variations
- Smoke n blue
- Gray and gray satin
- Cranberry, pink, rose
- Cobalt, cobalt satin, cobalt iridized, cobalt slag
- Taffy, chocolate (both), black
- Purple swirl
- Purple carnival
- Butterscotch slag
- Mandarin milk slag
- Turquoise
- Light yellow
- Wind frost (all colors)
- Green milk, green and milk slag, wintergreen
- Cobalt milk slag, MAC
- Peachblo
- Ritz blue
- Royal luster, Opal luster
- Blue milk
- Smoke
- Lime
- Black amethyst
- Hunter green, emerald green
- Willow blue
- Periwinkle
- Green opal
- Alexandrite
- Irish mist
- Dark green slag
- Milky blue
- Cloud 9
- Amber, Light amber, Honey
- Persimmon
- Peppermint