Post consumer glass cullet is glass cullet collected mainly from empty bottles and jars that have been left at kerbside pick up points, or dropped off at bottle recycling stations. This type of glass cullet has a wide range of applications, including ornamental ones, such as fish tank ornaments and gravel, tiles, paving, tableware, home ornaments, and even in some decorative aggregates, where glass cullet is added to concrete to produce a decorative finish.
Of course, the problem that many artisans and glass manufacturers face is obtaining [post consumer glass cullet that is the right color for their intended operation. In the past it has been simpler to simply obtain new glass products, but a rising environmental consciousness, and a desire to economize on material costs has sent many people back to looking at glass cullet as a raw material for their products.
Post consumer glass cullet generally comes in one of three color grades, amber, green, and clear. It is sometimes possible to obtain presorted glass cullet in which the glass ordered is of a uniform color, but it is still cheaper to obtain mixed color glass cullet and separate it ones self. This may not be a viable option for large scale commercial operations, but for craftspeople and smaller operations, it may be worth the saving in cost to take a little extra time to sort the cullet oneself. Mixed cullet generally originates from kerbside pickups, where different types of glass are tossed in together with other materials intended for recycling, such as papers and plastics, and the breakages and ensuing mixing of the various colors during transport results in the various shades of cullet being mixed together.
Once one has obtained either amber or green cullet, the problem then becomes obtaining the right sort of color for the specific application that one intends to use it for, not to mention the desired opacity. Most craftspeople and manufacturers of decorative products do not wish to restrict their products to being clear, brown, or green. In order to make visually appealing products, the glass cullet must be decolorized before the artisan or manufacturer adds their own colors to it.
Decolorizing Glass Cullet
This article supposes a basic level of competence and knowledge with regards to the handling and melting of glass cullet, and is by no means a complete guide. The information below simply provides a basic outline as to how the decolorization of post consumer glass cullet can be achieved.
Post consumer glass cullet can be decolorized in a variety of ways, and each type of glass cullet decolorizes differently.
Decolorizing Brown/Amber Glass
If zinc oxide is added to amber glass, the amber/brown color is lost and one is left with glass that retains a blue or green coloration. This is quite pretty, but if one would like to make the glass entirely clear, then erbium oxide and manganese oxide can be added to clear the color from the melt.
Decolorizing Green Glass
Green glass requires two stages to decolorize. Firstly, the melt must be oxidized, which changes the deep green color that most green glass cullet has into a more yellowish green color. Manganese Oxide can then be added to create a glass that is not clear, but is merely a grey color. From this base color, different agents can be added to create a wide range of varying colors.
Coloring Glass
Once the glass has been decolorised, there are a wide range of options available for recolorizing the melted glass. There are a wide range of commercial blended colorants available on the market, and these have been developed to the extent that making one’s own colorants is largely unnecessary. For those who like to experiment however, some common colorants and treatments include:
- Cobalt Carbonate
- Borax
- Zinc Oxide
- Manganese Dioxide
- Potassium Permagnate
- Erbium Oxide
- Neodymium Oxide
- Cerium Dioxide
- Titanium Dioxide
These can be blended in varying quantities to produce various results. Other factors which will affect the color of glass are the temperature of the melt, the atmosphere of the melt (whether it is neutral or oxidized), and the blends of glass cullet used in the melt if one begins by using mixed colored cullet, or uses varying proportions of differently colored cullet.
It is highly recommended that decolorization and colorization of glass cullet only be undertaken by those with sufficient training, as some of the chemicals are quite dangerous if handled incorrectly, and indeed, the processes involved in successfully working with glass are inordinately delicate.
Post Consumer Cullet
The ability to work with multiple colors of glass cullet, and to blend and work the material into new colors and forms is not merely an aesthetic undertaking. Whilst many craftspeople and manufacturers make beautiful products from post consumer cullet, there are also very real environmental benefits to taking post consumer glass cullet and recycling it into new products. It has been reported that merely recycling one glass bottle saves enough energy to power a light bulb for an hour, and yet much glass produced across the globe today is not recycled, but ends up in landfills, where it will remain for millenia. Those manufacturers and artisans who choose to use post consumer glass cullet as a raw material for their art and products are not just saving themselves some money, they are also helping to save the planet.
Using post consumer glass cullet beautifies the world twice, once when the earth’s resources are spared from making yet another unnecessary glass bottle, and for a second time when the decorative or artistic recycled product is made.
Glass cullet prices
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