Color can distinguish a glass container, shield its contents from unwanted ultraviolet rays or create variety within a brand category.
Glass color can be obtained by simply adding small quantities of different oxides:
- Chromium > Green
- Cobalt > Blue
- Nickel > Violet/Brown
- Selenium metal > Red
The raw materials used in commercial glass making contain iron oxide as an impurity, which imparts a yellow/green color to the glass.
To offset the yellow/green when making flint, or “colorless” glass, other colors are introduced by adding selenium and cobalt in proportions that yield gray glass that appears colorless, hence the term “decolorization.”
The Power of Color in Glass Packaging
If you’re trying to improve the quality of your packaging with glass, there are a few things you should understand. Glass color is about a lot more than looks; it’s a strategic business decision that can help determine how people look at your brand.
Glass packaging comes in an array of colors, from deep amber to cobalt blue, and each shade serves specific purposes while sending distinct messages to your customers.
There’s a lot of science that goes into not only the creation of this glass but how it impacts the brain.
Protection Meets Psychology
The right glass color doesn't just catch eyes on store shelves - it actively protects what's inside.
Amber: Take amber glass, for instance. These aren’t just pretty colored glass containers, this color blocks harmful UV rays and blue light wavelengths under 450 nanometers, making it perfect for products that need serious light protection. That's why you'll see so many essential oils and pharmaceuticals packaged in amber containers.
Blue: Cobalt blue glass offers similar protection against UV rays, though it can't filter out blue light quite like amber does. Many brands pick cobalt blue when they want that protective element while making a bold visual statement.
Green: Green glass rounds out the trio of protective colors, and while it might not block as much light as amber or cobalt, it still shields products better than clear glass.
Speaking Your Brand's Language Through Color
Colored glass bottles can help tell your customers more about what’s in them, even before they pick it up. Blue creates calmness which is perfect for skincare or premium water. There’s a reason why high-quality water brands usually use blue glass colorants for their packaging.
Black glass screams luxury and sophistication, and this is why you see it with high-end fragrances and gourmet oils.
White glass speaks for purity and cleanliness, making it a natural fit for natural products and cosmetics.
The Environmental Edge
Here’s another important thing to understand about colored glasses. Each color gets recycled separately to maintain quality so it’s 100% recyclable and can be melted and reformed endlessly.
Using recycled glass (called cullet) instead of raw materials cuts energy use by about 40% during production. By choosing glass packaging, you're picking a material that can be part of the circular economy indefinitely.
Glass Color Chemistry and Composition
Amber Colored Glass
The most common, amber glass is produced by combining iron, sulfur, and carbon. It's considered a “reduced” glass due to the relatively high level carbon use.
All commercial container glass formulations contain carbon, but most are “oxidized” glasses. Amber glass absorbs nearly all radiation consisting of wavelengths shorter than 450 nm, offering excellent protection from ultraviolet radiation (critical for products such as beer and certain drugs).
Green Colored Glass
Green glass is made by adding non-toxic Chrome Oxide (Cr+3), oxidized to make Emerald, Georgia, or Dead Leaf Green. The higher the concentration of Cr+3, the darker the color. Reduced green glass offers slight ultraviolet protection.
Blue Colored Glass
Blue glass color is created by adding cobalt oxide, a colorant so powerful that only a few parts per million is needed to produce a light blue color such as the shade often seen in packaging design for bottled water.
Blue glass is nearly always oxidized. To produce a light blue-green glass, sulfur is omitted. Using only iron and carbon creates reduced blue.
Creating a reduced blue is seldom done because of the degree of difficulty in fining the glass and controlling the color.
Most colored glasses are melted in glass tanks, the same method as flint glasses. Adding colorants to the forehearth, a brick lined canal that delivers glass to the forming machine of a flint glass furnace, produces oxidized colors.