Pyrex what is

But the percentage of glass cookware shattering unexpectedly is very small, according to Patty Davis, deputy director of communications and press secretary for the Consumer Product Safety Commission. To be clear, the reported injuries include glass bakeware from all manufacturers, not specifically Pyrex.

According to Davis, the CPSC is unable to release information about specific companies without following a public disclosure process. However, the SaferProducts. In many cases, the instances of exploding Pyrex reported to SaferProducts. Since customer reviews can last forever online, the mounting complaints about exploding tempered glass can seem unsettling, even though the occurrence is quite rare according to the CPSC and multiple glass experts we spoke to.

But when you consider the thousands of pieces made each day in a glass factory, the number of incidents reported is remarkably small. In most cases, we think the benefits of tempered glass—its durability and safer breakage patterns—outweigh the danger. Other than being completely surprised and a little annoyed about having to clean tiny bits of glass out of my sink , I was unhurt, not even a scratch. For example, a calculation published by the American Ceramic Society found that borosilicate glass can withstand a sudden temperature change of up to about degrees Fahrenheit, whereas tempered glass can withstand a temperature change of about degrees.

The publication references the tests performed by Consumer Reports , which used dry sand heated in casserole dishes. However, since sand gets much hotter than food, some experts say these tests which are often cited in news stories about Pyrex are too extreme and are not an accurate representation of durability under normal use.

According to excerpts provided to us by Hugh Rushing, former executive vice president of the CMA, the CMA tests suggest that glass bakeware should be able to withstand being abraded with sandpaper to simulate wear over time , heated in the oven for 20 minutes, and then submerged in a water bath with a temperature difference of degrees Fahrenheit.

This procedure was developed in conjunction with a committee of glass manufacturers and industry consultants, and it has been tested on a variety of glass samples from all the major glass producers, with the results submitted to an independent lab for analysis.

And though adhering to these standards is voluntary, Rushing told us that a majority of cookware retailers and manufacturers subscribe to them. It sounds obvious, but you can help extend the life of your glass bakeware and tableware by treating it with care. You may be subjecting your tempered wares to extreme temperature changes and other abuses without even realizing it. Here are some tips for minimizing the risk of tempered-glass items spontaneously breaking:.

You may be wondering: Why use tempered-glass bakeware at all? For baking, glass conducts heat gently and evenly and offers the advantage of allowing you to see whether the bottom of your food is fully cooked and browned. Glass is a state of matter that has characteristics similar to both crystalline solids and liquids. On a macroscopic level glass appears to be like solids. It is rigid and remains in one piece when removed from a container. However, on a molecular level, glasses are more like liquids.

In crystalline solids, molecules are arranged in an orderly fashion. In liquids they are randomly arranged. This random arrangement is also a characteristic of glass. Glass is typically made by heating crystalline compounds to temperatures high enough to melt them. Melting breaks the ordered molecular structure, leaving them in a disordered state. When the melted material is cooled, the molecules become locked in place before they can reform in the ordered crystalline structure.

The properties of a specific glass such as hardness, brittleness, clarity, and chemical and thermal resistance are dependent on its chemical composition. When Pyrex was being developed, scientists were trying to create a glass composition that had a high thermal resistance.

At some point it was discovered that glass compositions with boron could be heated to high temperatures without breaking. Boron, which is the fifth element on the periodic chart, has the unique ability to create a variety of chemical bonds.

When bonded with oxygen it can create a three dimensional structure that is strong. In a glass composition, this extra strength gives it thermal and chemical resistance that makes it useful for cooking applications, thermometers, and laboratory equipment. Pyrex also has a low alkali content that gives it high corrosion resistance.

While the exact date people found that sand could be combined and melted with other materials to produce glass is not known, its discovery was likely accidental. Formal processes for glassmaking have been known for over 3, years. In Mesopotamia, archeologists have uncovered clay tablets that contain ancient "instructions" for making glass in furnaces. Throughout history, glass production technology became more sophisticated.

People steadily discovered the best proportions to combine the raw materials and also learned manufacturing practices like glass blowing. During the early twentieth century, kerosene lanterns were widely used for streetlights and railroad signaling devices. Unfortunately, the glass used for making these lanterns was sensitive to the heat of the flame and would often break. Scientists began searching for glass formulas that could withstand heat.

The first experiments led to the discovery that when boric acid was present in the raw materials, the glass was more heat resistant.

These early formulas were chemically weak however, often breaking down in water. Work proceeded to find the right proportions of silica sand and boric oxide that would continue to be heat resistant and chemically stable.

In , an adequate formula was found. These glasses, called borosilicates, were then introduced into lantern production.

One of the original types of borosilicate glass introduced by the Corning Glass Works Company was brand-named Nonex. The potential for this product in the area of cooking was discovered in by Dr. Jesse T. Littleton who worked at Corning. He gave his wife a casserole dish made out of Nonex, the precursor to Pyrex. It worked as well as a ceramic cooking dish and a new era in cooking ware had begun.

The Nonex glass formula was revised to remove lead, and the ovenware was given to the Philadelphia Cooking School for more testing. A series of successful tests there led to the introduction of Pyrex ovenware in This same year the Corning Glass Works Company patented the formula and gave it the trademarked name Pyrex. It has been suggested that the term Pyrex was either a derivative of the word "pie" referring to its original use or the Greek "pyra," which means hearth.

In both cases, the "ex" suffix was used to give it brand-name similarity to Nonex. When World War I broke out, scientists who relied on German glass products found that the new Pyrex material met their needs for beakers, test tubes, and other laboratory glassware. Borosilicate glass has steadily been made more chemical, heat, and shock resistant. It has also been applied to numerous products such eyeglasses, telescopes, and electronic components.

Three classes of materials are used in making Pyrex including formers, fluxes, and stabilizers. Formers are the main ingredients in all glassmaking. These are crystalline materials that, when heated high enough, can be melted and cooled to create glass. Fluxes are compounds that help lower the temperature required to get the formers to melt. Stabilizers are materials that help keep glass from crumbling, breaking, or falling apart.

They are needed because fluxes typically destabilize glass compositions. To cleanse our palettes, we sniffed chopped watermelon, cucumber and canned corn held in Pyrex containers throughout the lab. Break out the Pyrex —the casserole, America's classic hard-times dish, is hot again.

It has been found that it imparts a violet red tint to the pyrex tubing after the latter has been used for a few combustions. Butter a square Pyrex pan and put in the graham-cracker dust to make,a crust. Over the whole pour some melted butter, cover the casserole, or pyrex plate and put it in the oven with a low fire. The two bounders stood there, encased in heat-resistant pyrex pants, expecting the natives to make things hot for them.