Most glassware used in the average home today is non-toxic. Soda Lime glass accounts for 90% of glass found in U.S. homes, is impermeable and does not leach heavy metals.
As part of our everyday lives, many of us regularly use two types of glass; soda-lime and borosilicate.
Glass produced for general use is inert (chemically inactive) and impermeable (will not absorb), making glass the safest material for preparing, serving, and storing food products.
When deciding what type of glass is right for your specific needs, it only makes sense to be informed about the glass you use.
I begin this article by exploring how most glass we use in the home is manufactured.
What is in Glass?
Making glass is relatively easy; we’ve been doing it for thousands of years.
Glass manufactured for food ware is about 70% sand, typically grains of quartz crystals composed of silicon dioxide.
Sand, Soda ash (sodium carbonate), and Limestone (calcium oxide) are the three primary raw materials or mineral ingredients in 90% of glass we use.
Along with sand, soda ash, and limestone, different minerals may be added to impart unique qualities to the glass, such as color or structural integrity in the case of aluminum oxide.
The addition of soda ash acts as a flux and reduces the temperature needed to melt sand and form glass.
Limestone is added to the mixture to give the glass stability, without which, glass could absorb liquids and eventually dissolve from contact with fluids.
The mixture known as ‘ batch ‘ is heated to about 1320 degrees Centigrade or 2400 degrees Fahrenheit.
A chemical reaction occurs when the mineral ingredients used during the glass manufacturing process have been heated, melted, and combined.
Though it has a solid form, its unstructured molecular structure is more that of a liquid than a solid or a structured crystalline group (mole).
The glass industry guards its exact percentages of each ingredient in batch recipes and production methods except in general terms.
A new amorphous solid substance has been created, absent the properties of the minerals combined in the batch to make the glass.
Allowed to ‘cool’ down to between 1600-1900 degrees Fahrenheit and can now be formed into drinking glasses, glass containers, and countless other objects in the production process.
Once turned into the desired object, the glass will go through another process to either anneal or temper the glass.
Now formed into a mason jar, perfume bottle, or beer bottle, you have an impervious, non-toxic glass shield; the glass doesn’t let things out, and it doesn’t allow things in.
Soda Lime Glassware
Though it sounds almost like something to drink, Soda-lime refers to the minerals used to create the glass.
Also known as regular, soft, and ordinary glass, it is the most widely used type of glassware in the home.
Unlike other glasses such as borosilicate, “soda glass” is relatively inexpensive to make, easy to mold into endless shapes and sizes, and affordable.
Soda Lime glass is composed of approximately 70% sand,15% Soda ash, 9% Lime, and the remainder 6% are of varying minerals/additives.
Soda-lime glass is used for food and drink packaging; its smooth surface is non-reactive/resistant to acidic foods but does not stand up to sudden temperature changes.
The ability to store products for great lengths of time and its low cost to produce makes glass the ideal storage container for edible products.
Soda-lime glass is one of the better recyclable materials because it takes less energy to melt used glass (cullet) than to start from scratch with minerals.
Soda-lime can be remelted and turned into new products many times over.
Since the 1980s, Soda-lime glass has replaced its counterpart, Borosilicate glass, in many glass products.
While maintaining the original look, all glass bakeware manufacturers in the U.S. now produce tempered soda-lime bakeware instead of borosilicate bakeware.
This “ordinary glass” is easier to mold at lower temperatures and does not rely on boron as an ingredient, therefore making it less expensive to produce.
Non-toxic and able to withstand the high temperatures of the home oven, borosilicate glass became invaluable in 20th-century kitchens.
Developed in the late 19th century and commonly known as Pyrex, borosilicate glass can still be found as bakeware for the home oven and is an excellent choice for heat-resistant glass cups for morning coffee.
Borosilicate glass is heat resistant with a low coefficient of thermal expansion and can handle higher temperatures, and extreme instant temperature changes than soda-lime glass are capable of.
Boron trioxide replaces limestone to create borosilicate, scratch, and thermal shock-resistant glass; boron is what makes the almost indestructible magic happen in borosilicate glass.
Borosilicate glass is harder than soda-lime glass, resisting chips and scratches better.
Borosilicate glass is also one of the best options for sports bottles.
Not only are sports bottles made of “boro,” but test tubes, funnels, and beakers made of Borosilicate glass are used in laboratories because the material is inert (does not interact with chemicals) and has a low coefficient of thermal expansion.
It has a forgiving nature regarding its high heat tolerance, ability to sustain dramatic temperature change, ability to resist corrosion and withstand mechanical shock due to impact better than soda-lime glass.
Unlike Soda-Lime glass, Borosilicate glass is not so recyclable because there is no market for it, and it cannot be added to soda-lime glass as cullet in the recycling process.
Crushed-up soda-lime bottles, jars, etc.(cullet) can be added straight into the mix to remelt and make new soda-lime glass products.
Tempered vs. Annealed
Most regular glass is either annealed (allowed to cool at a predetermined rate to release internal stresses) or tempered.
Tempering is reheating the glass item and then rapidly cooling it.
Tempering makes the outer surface of the glass compressed, vastly tougher and leaves the inner core in a state of tension.
The tempered glass is now more abrasion resistant, resists chips, and will turn into cubes rather than shards when broken.
Annealed glass without tempering will turn into glass shards when broken.
Due to the possibility of thermal shock breaking it, un-tempered or annealed soda-lime glass is not suitable for hot drinks/liquids/foods.
Thermal Shock can occur when one area of an item (in this case, glassware) of glass instantly expands faster than the rest of the piece of glass, resulting in the item shattering.
Tempering the glass allows for remarkable resilience to the expansion of the glass and shattering due to thermal shock.
Tempering the soda-lime glass makes the glass about three times stronger and less prone to shatter when subjected to thermal shock.
Duralex glasses are an example of tempered glass and call their products ‘adaptable modern glassware,’ being able to go straight from the freezer to the microwave.
The glass of this type can be found in drinking glasses, food containers, mason jars, glass dinner plates, saucers, and cups.
“Pyrex” has been made of tempered soda-lime glass in the U.S. since the 1980s
Due to the possibility of thermal shock breaking it, un-tempered soda-lime glass is not suitable for hot drinks/liquids/foods.
With that being said, actual Pyrex and Pyrex type borosilicate bakeware can still be purchased, Made in France and other European countries.
Does Glass Contain Lead?
There is no lead in regular everyday drinking glasses or most other objects made of glass for normal everyday use that are currently manufactured or sold in the U.S. and marketed to prepare, serve, or store food products.*
*Of course, the exception to this is leaded glass products that are specifically made with lead and usually reserved for wine, cocktail glasses, and decanter use.
I’ve written a related article on the easiest way to test and determine if you have leaded or lead-free glasses.
Quality lead-free glassware brands make “Crystal” with the perfect weight and nice feel of lead glass, just non-toxic.
Zwiesel Glas Pure Tritan Crystal Stemware Glassware Collection
Lead-Free Glassware Brands
Great for the Bar or for everyday use from the kitchen, Anchor Hocking, Le’raze, and Libbey, are fine examples of affordable non-toxic glasses that are dishwasher safe and meant to be used.
Is Glass From China Safe?
The U.S. strictly monitors the glassware produced in China destined for the U.S. market.
Sticking with known glassware manufacturers will assure you that your glassware is safe.
Enameled Drinking Glasses
Ten+ years ago, there was a large recall of Novelty Design glassware; decorated with specific designs such as “Superheroes.”
Recalled due to high harmful levels of lead and cadmium (toxic chemicals known to cause health issues) content in the enamel used to create the designs.
The concern is that of possible accidental lead poisoning and cadmium exposure.
Children are more susceptible to lead poisoning, and keeping any lead substance away from them is advisable, offering them only safe drinking glasses.
It is not unrealistic to think that some people may still have some of the recalled lead and cadmium-painted “Super Hero” novelty-type glassware on the third shelf of the last cupboard over.
With lead being a concern of all human beings, it is safe to say that many adults have heard that using such glassware can cause health issues and could be (even in small amounts) detrimental to human health.
It is a bit concerning that the items came from large corporations known by most (not naming names) and were explicitly aimed at children’s attention.
One party claimed that the product was marketed for adults, but the merchandise was promoted alongside children’s lunch boxes and other childrens’ products.
I believe it still leaves a lot of questions as to why this was overlooked and why they did not test them before being made available to the public.
It is no secret that paint, ink, and glazes can contain potentially hazardous chemicals.
Most decorated glassware produced today for use in the U.S. has what is deemed “acceptable levels” of toxins due to the use of low-lead enamels.
Though I am personally not a fan of decorated glassware, I am happy to report that most of today’s products are far safer than just a few years back due to the use of low-lead enamels.
Vintage Mixing Bowls
Many Pyrex glass lead, cadmium-painted casserole dishes, and mixing bowls are still on kitchen shelves.
This kitchenware had been the mainstay of the American kitchen with its classic look since the early 1950s.
Working double duty after a meal as food storage containers in the refrigerator, most American kitchens had one form or another.
Anchor Hocking Glass
There have been reports of exploding bakeware; tempered soda lime bakeware to be more exact.
Anchor Hocking has responded to reports of “exploding” bakeware and claimed that “this method of failure is by design” in their products.
The premise is, that the small cube-shaped pieces of glass are less likely to lead to injury than the shards of glass that are left if an item of borosilicate bakeware were to break.
They state that their tempered, or “thermally strengthened” Soda-lime bakeware has twice the mechanical strength as that of annealed borosilicate glassware and has greater or equal thermal shock resistance.
Anchor Hocking also goes on to say that since they switched to making their bakeware with their soda-lime formula, accidents from product failure declined.
This in-depth article by Anchor Hocking titled ‘Bakeware Facts‘ is really worth reading and could help a person with their purchase choice.
In over four decades of cooking and baking experience, I’ve never seen it happen in any restaurant that I’ve worked in, or had it happen at home; with safe and recommended usage, exploding bakeware is a rather uncommon occurrence.
Any glassware that is intended for use in food or drink preparation that is chipped, scratched, or otherwise damaged should be discarded and not be used.
Any hot dish coming from the oven should be placed on hot pads to reduce accidental breakage.
Avoid wet surfaces, damp towels, or cooling metal racks/metal trivets.
Corelle’s Frost White dishes are durable, good-looking, and affordable.
Made of a glass triple laminate called Vitrelle, these dishes are more of the “adaptable modern glassware” as they can be safely used to heat or reheat foods going straight from the freezer to the microwave.
Corelle is said to be conventional oven safe up to 350 degrees, but it is not designed to be and should never be used on the stove-top.
As with any glass item that is used to prepare or serve foodstuffs, Corelle should be thrown away if any cracks, chips, or deep abrasions are noticed as it can compromise the structural integrity of the glass.
Care should be taken when cleaning Corelle, never using any abrasive scrubber, or using metal utensils to remove baked-on foodstuffs.
Manufacturing attractive lead and cadmium-free dinnerware of nearly indestructible material, a set of easy-cleaning Corelle plates and bowls are a great addition to the family dinner table.
This was not always the case, in a statement from Dec. 2019, a Corelle representative, claimed that prior to the 1990s, some of their company’s and most decorated glass from any part of the world contained lead.
The representative goes on to say that since the mid-2000’s that all of their product has been lead-free.
Article pertaining to this can be found here: Lead Safe Mama article link.
It was recommended that certain dinnerware made before the said time period was better suited as decorative wall art.
Glass Drinking Bottles
Borosilicate drinking bottles are super tough, impact-resistant, they don’t scratch easily, and you can add hot liquids to them without the concern of them shattering.
Plastic Drinking Bottles
I would be remiss if I were not to mention the ever-popular plastic drinking bottles.
I’m not such a fan of any plastic, probably because as a kid in the 1960s it seemed as if everything then had to be made of plastic; the plastic then seemed to have an “off” smell, I can still remember it.
Today’s plastic is made of safer, different materials than when I and many other young kids were drinking our share of Kool-Aid and other cold beverages from a plastic container and plastic cups.
It is said that Polyethylene bottles are safe to drink from and will have the recycle number of 1 on the bottom;
And that a person should stay away from any Polycarbonates due to BPAs.
Much of today’s plasticware is free of BPA’s, read the label before purchasing to make sure it says “BPA Free.”
Rubbermaid’s plastic products have been free of BPAs since January of 2010.
Tupperware no longer used BPA in the manufacture of their type of plastic products after 3/2010.
Stainless Steel Bottles
Virtually indestructible, Stainless Steel bottles are favored by many and do not leach heavy metals with regular use.
Manufacturers recommend a very thorough cleaning of the bottle.
Allowing anything to build upon the bottle’s surface could start to compromise the metal.
Equal parts of vinegar and water are a good solution to clean stainless steel, with a good rinse afterward.
Stainless steel bottles should not be cleaned with any abrasive scrubber, a bottle brush is recommended to clean a stainless steel bottle which will not affect the metal.
Once formed into the glass, a person is more likely to suffer an injury due to misuse, accident, or product failure than to suffer any physical harm from the raw materials that were used to make an item of common glassware.
I’ve done my best to research and be accurate in what I have found and recorded here in this article; I was quite surprised to find so much information that was contrary to what was being said elsewhere; if you find something that you disagree with, or have more information about, please feel free to contact me, I welcome your input.
Hopefully, you have found this article about non-toxic glassware helpful and it will be beneficial to you in your daily use and future purchases of glassware.
Thank you for reading!
Corning Museum of Glass
The Pyrex Collector
Advanced Technical Products
The Florida Times-Union
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