Let me tell you right off that it was great to have such a strong turnout for the pruning demonstration last Saturday. We covered a lot in two hours, and it was fun to see so many interested in how to take care of their orchard, grapes and berries. We even looked at a few ornamental pruning techniques for the whole yardscape.
It’s become evident that we have a growing population of gardening enthusiasts that are keen to increase their proficiencies and sense of self-reliance. We’ve noticed that each year there are more and more yardscapes that are candidates for the annual garden tour as well. It’s fun to see the greening of the Tooele Valley!
As the days are starting to warm and the sun is out more, I’m reminded that it won’t be too long until we see fruit set on our orchard trees. That brings to mind our annual rituals of canning up pie fillings, juices and jams. I know there will be some really good eating in the not-too-distant future! And, once again, a common item caught my attention — the glass jars that serve our preservation efforts so well.
We recently wrote an article on the craft and practice of canning foods, so I won’t discuss that again. No, our focus will be on one of the most common and adaptable materials available today: glass!
You’ve heard me say that if something isn’t grown, it’s mined. True to that maxim, glass is made from silica sand, and depending on the application, some other additives. Sand is one of the main categories that we gardeners use to describe types of soil. When you conduct a soil composition test, the major components measured include clay, silt, sand and organic material.
For us here in Tooele Valley who typically have a large percentage of clay in our garden and flower beds, sand can sound pretty attractive. A common question asked in Master Gardener soil classes is if it’s beneficial to add a lot of sand to a clay plot to make it more “open” and more likely to drain moisture. Although a sandy soil certainly does drain easily, it also doesn’t hold nutrients as long or keep moisture at the root zone for an extended period of time. Besides, we have a lot of limestone and calcium components in our soil. What happens when you mix sand and calcium? You get a form of concrete! It’s really not that bad, but a better approach is to add copious amounts of organic materials over time to enrich and open the soil.
While sand is of value to us as gardeners, it’s paramount to the manufacture of glass. It’s the primary ingredient for all types of glasses. Silica sand begins as quartz, eventually weathering and fracturing into grains of sand. Glass can be made from recycled glass objects, but without the creation of newly manufactured glass, the supply of existing glass that is ready to be “upcycled” would eventually be depleted.
The major producers of glass-making sand include Australia, Vietnam, Malaysia, Indonesia, India, Egypt and China. There are silica sand deposits in the U.S. as well.
Would you recognize silica sand if you saw it? If you have stood on the beach at your favorite ocean destination, with bright white or off-white sand, you’ve stood on this incredible raw material. The reason we need this fine, white, silicon dioxide sand and why it is harvested from large deposits (not at the beach typically!) is because it is very pure. If there are unwanted chemicals and compounds, they will complicate the manufacturing process. Glass production also requires limestone and soda ash and, if coloring is desired, other substances as well.
While there are variations on how glass is made, and what it will be used for, there are some basics that apply to all processes. The process begins with loose sand that is heated until it melts and turns into a liquid. Lest you think that favorite sunny beach of yours is turning into glass under the heat of sunshine, it takes a LOT more than that. Sand melts at 3,090 degrees Fahrenheit!
There are additives that can be used to lower the melting point, with varying results, uses and levels of quality. Soda-lime glass has the lowest melting point but must be cooled slowly, or it will shatter due to thermal stress. It’s made by adding washing soda, lime or borax to the sand. This results in a disruption of the quartz-crystal structure of silica. It will still take 2,000-degree heat to produce this type of glass! Borosilicate glass, (us mere mortals would know this as “Pyrex”), melts at a higher temperature but can be cooled more rapidly. It is much more thermally stable, as any baker that uses Pyrex baking pans knows.
Since sand has been with us since the beginning of recorded time, has glass been in existence as well? Yes and no. “Yes” in that there have been natural forms of glass with us since we’ve been around. “No” in that glass used for bottles, windows, packaging, lenses, decorations and a myriad of other things is a much more modern occurrence.
As a child, I was familiar with one naturally occurring glass — obsidian. Being from Arizona, which has a robust history of Native Americans, we knew these black glass stones as “Apache’s Tears.” It wasn’t too uncommon to locate arrowheads that had been crafted by earlier peoples. A real treasure would be when you would find arrow points fashioned out of obsidian — a black glass arrowhead! These sported chipped edges along each side, relatively sharp as the glass had fractured away. Obsidian is formed by volcanic action when felsic lava cools rapidly. This type of lava contains about 70 percent silica. There’s our friend silica again!
There’s another naturally-occurring glass that is equally intriguing. It has a funky name; fulgurite. It’s formed when lighting strikes sandy deposits. If you’ve watched Reese Witherspoon’s Sweet Home Alabama, you’ve seen reference to fulgurite. One of the main characters in the film encourages the creation of these unique shapes by sticking metal rods into the sand along the beach. Lightning strikes create temperatures of several thousand degrees in an instant, with the heat rapidly dissipating because of the mass of sand around it. Random forms of glass are the result, with differing coloration depending on what minerals were present in the melted sand. Fascinating stuff!
It is thought that man discovered that glass could be made around 7,000 years ago. One theory is that Phoenician merchants and sailors built cooking fires over sand that had the right combination of substances. If a fire has a blast of oxygen blown into it (even from natural winds), and the supply of fuel is ample, very high temperatures can be attained. It’s possible this is the way it occurred. Whatever did happen, somewhere along the way, we discovered that glass could be made and various types of glasses and manufacturing techniques were perfected.
Glass is an incredibly adaptable, and in many cases, recyclable, material. Early on, it was recognized as valuable for windows. Glass back then was thick and inconsistent, and not that easy to see through. Yet, it allowed light in and afforded protection from the elements.
At some point, people learned that glass could be colored internally, by adding various minerals as it was made. When it was also discovered that glass could be painted and then fired to make the painted images durable, and that shaped lead could hold pieces of glass together, stained glass panels and scenes came into being. There are age-old cathedrals in Europe that are a testament to this.
There are so many glass products, in a wide range of categories, one would be hard-pressed to create even a moderately complete list. The catalog would include structural glass for buildings and furniture, window and automotive uses, laboratory, scientific and medical applications, baking utensils, bottles, jugs, pitchers, jars, cups and glasses, to camera, optic and telescope lenses, computers, cell phones, solar panels, mirrors, jewelry and artistic objects. Suffice it to say that our world would be a much less advanced and enjoyable if we didn’t have glass.
And to think — all these have their genesis in “plain old” sand. Almost magical!
Jay Cooper can be contacted at firstname.lastname@example.org, or you can visit his channel at youtube.com/dirtfarmerjay for videos on the hands-on life of gardening, shop and home skills, culinary arts and landscaping.