glass bottles under heat

    Published: July 20, 2016

    How are Glass Bottles Made?

    At Pelican Water, we’ve always advocated the use of glass bottles over plastic, and we’re very proud of our own Pelican Glass Water Bottles with their elegant necks and well-shaped bodies.

    We thought it would be interesting to explore the automated process a little. We were familiar with the image of the skilled glassblower, blowing globs of molten glass into beautiful shapes. Artists still practice this enchanting skill today, but most bottles are now factory-made.

    To make glass bottles, first you need glass stock feed. This raw material is made up of 90 percent silica, calcium, and lime, with smaller amounts of aluminum oxide, ferric oxide, sulfur trioxide, and magnesia. In addition, the manufacturer adds cullet, or recycled glass, to the stock feed. Depending on the manufacturer, cullet amounts for 15 to 50 percent of raw material.

    The stock feed and cullet is melted into a furnace, where temperatures can reach a blistering 1675 Fahrenheit. These extreme temperatures turn the raw materials into molten glass.

    A shearing blade cuts off portions of the glass into “gobs,” cylinders of molten glass which will become the bottles. Now one of two techniques shapes the glass:

    Press and Blow: The gob is pressed into a mold with a plunger, then flipped and placed in a blow mold, where compressed air shapes the interior of the bottle. This method is usually employed for large-mouth glass containers.

    Blow and Blow: Compressed air shapes the gob into a mold to form the bottle neck. The glass is then flipped into a second mold, and is blown to form the interior. Most long-necked bottles are formed using the blow and blow method.

    Once formed, glass bottles are placed in an annealing oven that reheats and cools the glass. This strengthens the finished bottle, preventing cracks and breaks caused by handling or temperature changes.

    Why Glass?
    We chose glass for our table bottles over plastic for a number of reasons. Unlike plastic, glass is 100 percent recyclable: up to 80 percent of recovered glass bottles are made into new bottles. In comparison, the US only recycles 25 percent of its plastic; 38 million plastic bottles are discarded every year.

    Glass has personal health benefits as well. Nonporous and impermeable, a glass bottle does not transfer chemicals into its contents. You get no aftertaste, and avoid ingesting harmful substances such as BPA, which have been shown to leach into plastic bottle contents over time.

    And while we might be biased, we think our glass table bottles look smarter than any disposable plastic water bottle. You get style, substance, and durability with glass. What’s not to like?