It is heat-absorbent, retaining heat instead of conducting it, and absorbs heat better than metal. Glass can reflect, bend, transmit, and absorb light with high accuracy, and is valued for its optical properties.
It strongly resists electrical current and stores electricity well. This article compares two types of glass: soda lime glass and borosilicate glass.
They are two popular kinds of glass that are used for similar purposes and have some of the same properties. Soda lime glass , also known as soda-lime-silica glass or window glass, is the most common and least expensive type of glass. The soda lowers the temperature at which the silica melts, while the lime stabilizes the silica.
It is a softer glass, which is an asset because it makes fabrication via cutting easier, but this does mean it is less scratch-resistant than other types of glass, such as borosilicate.
Soda-lime glass is often chemically strengthened to increase its strength, or it can be tempered to increase its thermal shock resistance and strength. As its nickname suggests, it is commonly used in windows.
Tempered soda lime glass is often used for cookware, and is now used in the United States to make Pyrex, a popular dishware brand. Durable and heat resistant, borosilicate glass is the material of choice for a wide range of applications, from cookware to laboratory use. Creating borosilicate glass requires higher temperatures than those necessary for the production of regular glass, although this also accounts for its higher heat resistance.
It also faces far less material stress than regular glass due to its lower thermal expansion coefficient, which also adds to its exceptional performance at high temperatures. Additionally, borosilicate glass is far more durable than traditional glass and can withstand accidents that would break other glassware. The main difference between soda-lime glass and borosilicate glass is their silicon dioxide and boron trioxide content. Soda-lime glass typically contains 69 per cent silicon dioxide compared to It also contains far less boron trioxide: just 1 per cent compared to 13 per cent in borosilicate.
Four factors differentiate borosilicate glass from its regular soda-lime counterpart. The borosilicate glass is harder than regular glass as it can be moulded into more complex shapes.
It is also more resistant to acid erosion which is why you commonly find it used in chemistry labs. Just like regular glass, borosilicate glass is completely non-toxic. Companies like Pyrex use it as a safe material to make heat-resistant glass jugs, glass bottles, and cookware. Food and drink from borosilicate containers often taste better because the material does not leach out, as it does in plastic bottles and other BPA-containing packaging.
Borosilicate glass itself is BPA-free. However, some products which use borosilicate may have other components made from BPA plastic. When choosing borosilicate products, check to see the chemical composition of any plastic products.
All pure borosilicate glass products like baking dishes are per cent BPA-free. Borosilicate glass is safe to drink from, just like regular glass. Borosilicate glass helps you to improve sustainability and keep plastic waste out of landfill, which is good news for the environment.
Plastic pollution is a significant concern, so using a reusable jug or bottle made of borosilicate glass can help enormously. Borosilicate glass is highly durable. Borosilicate glass requires higher temperatures to make than regular soda-lime glass. The higher manufacturing temperatures are what confers its heat resistance.
The higher manufacturing temperatures also make the glass much stronger. First , borosilicate glass expands by only half the amount of regular soda-lime glass when exposed to heat. Its low coefficient of thermal expansion means that it is far less liable to crack than regular glass.
Second , borosilicate glass is much harder and stronger than soda-lime glass. I have done so many times, knowing that borosilicate lab glassware is capable of withstanding large differences in temperature without cracking. I had always assumed that Pyrex glass was synonymous with borosilicate, thermal-shock resistant glass. After the sale, Corning continued to sell borosilicate glass for laboratory use under the Pyrex name.
However, World Kitchens began to sell soda lime glass for kitchen use — also under the Pyrex name. World Kitchens made this change because soda lime glass is cheaper to manufacture and more resistant to breakage from mechanical stress than borosilicate glass. Now Pyrex is simply a brand name that has nothing to do with the chemistry of the glassware being sold. The difference in heat shock resistance between borosilicate glass and soda lime glass can be quantified using some simple relationships.
Borosilicate glass has a low coefficient of thermal expansion 3 x 10 -6 K -1 , which means that borosilicate glass does not undergo sizeable expansion upon heating or contraction upon cooling.
On the other hand, soda lime glass has a high coefficient of thermal expansion 9 x 10 -6 K -1 , which means that it will undergo sizeable expansion upon heating and contraction upon cooling.
The following equation provides a simple quantitative relationship between thermal shock and coefficient of thermal expansion,.
The linear elastic thermal stress, , on a glass is a measure of the stress the glass can withstand without shattering:. Equation 1. In Equation 1, is the temperature differential a glass object can experience without breaking, is the coefficient of thermal expansion of the glass and E is the elastic modulus of the glass.
Most glasses — including both borosilicate and soda lime glasses — are capable of withstanding stresses of about psi.
Borosilicate and soda lime glass have a similar elastic modulus: 9. Using the appropriate values for each glass type in Equation 1, we see that borosilicate glass can experience a K difference in temperature without shattering. However, soda lime glass can only experience a 54 K difference in temperature before shattering. I wish someone would have told me all this a few years ago….
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