Glass is glass … well not quite.
Window glass (plate glass), tumblers and Pyrex jugs and dishes are made from tempered glass.
This is chemically different from the glass used to make bottles and jars.
Also know as toughened glass, tempered glass melts at a higher temperature than normal glass. This means that it can cause un-melted blobs to appear in the recycled glass creating serious quality problems for manufacturers. That, in short, is why we cannot take toughened glass.
Glass bottles and jars are made from what is known as soda-lime glass. That is essentially sand that is heated to a very high temperature and then mixed with other chemicals. Glass gets its different colours, for example, by adding different chemicals.
Toughened glass is known in the trade as Borosilicate glass. This glass only starts to melt at much higher temperatures than standard soda-lime glass due to the different chemicals added.
Glass is the only materials that can be recycled 100% again and again with no loss in quality or purity. Every tonne of glass recycled saves 1.2 tonnes of raw materials being used (from sand mining to transportation) and has a positive impact reducing greenhouse gas emissions.
The glass we collect in Newport goes to Cwmbran to make Aluminosilicate glass – known to you and me as fibreglass. The glass is heated to more than 1,400 degrees C and then forced, at high pressure, through very small (5 – 25 micrometer) holes. A micrometer is one millionth of a meter! As the tiny strands of glass come out they are sprayed with water and other chemicals that help the strands bind together but also make the material flexible.