Types of Materials used for making tinted (coloured) Glass

Tinted float glass gets its color from metal oxide additives mixed into the raw glass batch (silica sand, soda ash, limestone, dolomite) before it's melted and floated on the molten tin bath. Here's what produces the common shades:

Bronze/Brown

Iron oxide (Fe₂O₃) combined with a reducing agent — often carbon or sulfur compounds — to shift the color toward brown/bronze tones rather than green.

Green

Iron oxide (both ferrous Fe²⁺ and ferric Fe³⁺ forms) is the primary colorant. Higher iron content, especially ferrous iron, produces deeper greens. Sometimes chromium oxide is added for richer "emerald" tones.

Grey

A combination of iron oxide, cobalt oxide, and nickel oxide (or selenium in some formulations) balances out to a neutral grey rather than a color-biased tint.

Blue

Cobalt oxide is the main colorant, sometimes blended with iron and copper oxides depending on the depth and hue desired.

Black (very dark tints)

Higher concentrations of iron, cobalt, and chromium oxides together, sometimes with additional carbon, to absorb most visible light.

Pink/Rose

Selenium compounds, often paired with small amounts of cobalt to balance the tone.

Amber/Yellow

Sulfur combined with iron oxide and carbon (a "sulfur-carbon-iron" chromophore) — this is also how amber glass bottles are traditionally colored.

Basic mechanism

The metal oxide ions absorb specific wavelengths of visible light as it passes through the glass, transmitting only the complementary wavelengths — which is what gives the glass its perceived color. The exact hue and depth depend on:

The specific oxide(s) used

Their concentration (typically fractions of a percent by weight)

The oxidation state of the metal ion (e.g., iron behaves very differently as Fe²⁺ vs Fe³⁺)

Glass thickness (thicker glass = more saturated color, since more material means more light absorption)

The tin bath itself (used to float and flatten the glass) doesn't contribute color — it just makes contact with the underside of the glass, though it can leave a very faint "tin side" that fluoresces under UV light, unrelated to the tint.