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Dear Glass Detective,
Can half-gallon or one-gallon milk bottles be made with toughened (tempered) glass so the container will not easily break? In the event it does crack, or shatter, can it be easily collected and repurposed-melted back to a glass bottle and reused or recycled? I see plastic as a dead end material, and recall the milk bottles delivered to my parents house door, fresh every morning, even in Manhattan elevator apartment buildings in NYC. The additional layer of shock resistant material to strengthen and reduce breakage could make a new kind of liquid container. Even broken it could be recycled and, if wrapped with aluminum or metallic wire frames, would hold together so it need not be thrown away.
Sand is now the most used natural resource after H20. Better we reuse our bottles by washing them and even melting the busted ones than we abuse rivers, dunes and beaches to use new, clean and “virgin” sand, which we will run out of easily. Do you know of a glass type that is similar to what I describe?
New York, New York
Thank you for making contact with the Glass Detective with your questions and concerns regarding the use of glass bottles in lieu of plastic ones. While virtually all of our dealings are with automotive glass (windshields, door glass and such) or architectural glass (windows, mirrors and so forth) I did want to offer up a few observations and an opinion or two on your glass bottle questions and remarks because I do have just a little knowledge here. So here we go:
First, glass is glass is glass. It all starts out with a whole bunch of silica (sand). Depending on what the end-use will be, that silica gets mixed with lime, calcium oxide, aluminum oxide, sulfur trioxide, magnesia and a few other additives. As much as 50% of the mix includes old broken glass. Yes, glass is an incredibly good recycling product which is one of the many reasons that I am a big proponent of glass bottles instead of plastic ones.
Manufacturers of both bottled glass and plate/float glass long ago discovered that they get better yields when they mix high percentages of recycled glass (what those in the industry refer to as cullet) in with new batches. Some bottled glass products use as much as 50% recycled glass to make new product. It all then gets melted into a kind of thick liquid goo and is then processed into the finished product. There are numerous videos of the glass manufacturing process online They’re fascinating to watch.
You stated that you see “plastic as a dead-end” but in reality, there are many very good uses for plastic materials. However, like you, I don’t think bottles are necessarily always the best use for plastic. You also recollected the use of glass milk bottles being delivered to homes, even in Manhattan highrises. Glass bottles of milk are in fact still being delivered in some metropolitan areas (including mine in the suburbs of Chicago) on a daily basis. Many people believe that plastic bottles affect the taste and quality of certain liquids—milk products especially. But I think we need to be realistic; plastic is used for bottles and bags and all kinds of other things because it is less expensive than other products. And glass does break!
Plastic waste has become a world problem and the thinner the material, the less likely people are to even attempt to recycle it. We know that glass is quite easy to recycle and plays an important role in the making of new glass. But in my opinion, without some type of legislation limiting the use of plastics, I don’t see glass milk bottles or soft drink bottles or other types of bottles making a big comeback soon. You also asked if glass bottles could be treated in such a way as to make them stronger and less likely to break. The short answer is that there may be ways to treat them/coat them or strengthen them, but this would most certainly add cost. Depending on the treatment process, it could make them less desirable for recycling purposes. You impress me as someone who is concerned about the environment and our earth’s natural resources. I too have these concerns. So personally, whenever I have the option of glass (or paper) instead of plastic, I take it. I’m guessing you do too. I hope this response is of some value to you. Thank you again for making contact with the Glass.com Glass Detective and have a wonderful day.
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