Borosilicate vs Normal Glass: 5 Differences That Matter for Drinks

Borosilicate glass vs normal glass comes down to heat. Borosilicate glass has boron in it, so it grows very little when it gets hot. Normal glass is soda-lime glass. It grows about three times as much, says SCHOTT. In a Corning plunge test, borosilicate plates took a sudden drop of 150 to 180 degrees C. Soda-lime plates took only 50 to 65 degrees C. So borosilicate is the safer glass for hot and cold drinks. And Borosil? That is a brand name, not a type of glass.

What Is Borosilicate Glass?

Borosilicate glass is glass made with boron trioxide added to the silica. The boron makes the glass grow very little when it heats up. That is the whole point of the material. SCHOTT, a German maker of this glass, gives the number for its BOROFLOAT 33. Its heat growth, called the coefficient of thermal expansion, is three times lower than that of soda-lime glass. Glass cracks when one part grows more than the part next to it. A glass that barely grows rarely cracks.

"Normal glass" means soda-lime glass. It is the plain glass in windows, jam jars and most tumblers. It is made from silica, soda ash and limestone. It is cheap to make and fine at room temperature. When people search for "normal glass vs borosilicate", soda-lime is the glass they mean.

Borosilicate vs Regular (Soda-Lime) Glass

Why Does This Matter for a Beverage Dispenser?

A glass dispenser has a harder job than most glass in the kitchen. It may hold hot drinks and cold drinks. It may hold sour drinks like lemon or tamarind for hours. It may go from the fridge to a warm counter, or out into the sun. A vase can be made of any glass. A dispenser for your family's drinks should be borosilicate:

• Hot drinks: Warm lemon honey water or hot tea is not the problem. A sudden pour of hot liquid into cold glass is. Borosilicate takes a far bigger sudden jump than soda-lime glass.
• Fridge to counter: A chilled jar that meets a warm drink or a hot room has a sudden change too. The less the glass grows with heat, the less stress it feels.
• Acidic drinks: Jaljeera, nimbu pani and kokum sharbat are all sour. SCHOTT puts its borosilicate in the top class for water and acid resistance. It says the glass has far fewer sodium ions than soda-lime glass, and holds them more tightly.
• Sun exposure: A dispenser on an outdoor table warms up in the sun, often on one side only. SCHOTT notes its glass copes with a hot centre next to a cold edge. Soda-lime glass copes far less well.

The InstaCuppa Glass Dispenser is made of thick borosilicate glass. Its product page rates it from -20°C to 150°C. That covers every case above. The same page gives one rule: do not pour boiling water into a cold jar. Let the water cool for 2 to 3 minutes first. The inbuilt thermometer is a drink thermometer. It shows if a drink is still cold, or cool enough for a child. It is not meant to measure boiling water.

What Does Borosil Mean? Borosil vs Borosilicate

Borosil is a brand name, not a type of glass. It belongs to Borosil Limited, an Indian glassware company. Its corporate office is in Mumbai, says its contact page. Its own history page says the company began in 1962. The same page says the name is inspired by borosilicate glass, the company's main product. So Borosil means the company. Borosilicate means the glass.

Are Borosil and borosilicate the same? No. Borosilicate is a type of glass. Anyone, anywhere, can make it. The names sound alike because the brand was named after the glass it became known for.

That difference matters when you shop. A Borosil product is not always borosilicate glass. A borosilicate product is not always from Borosil. Borosil's own site lists borosilicate glass, serveware and drinkware, Larah opalware, a stainless steel range and appliances. So "it is Borosil" tells you the brand, not the glass.

Is Borosil glass or plastic? Borosil is a company, so the answer depends on the item. Read the material line on that item's box or listing. The same goes for the Borosil glass temperature range. Use the rating printed for that one product.

• Borosilicate = the material. Low thermal expansion, high chemical resistance, used in laboratory glassware.
• Borosil = the brand. An Indian company that sells borosilicate products and also sells other things.
• Pyrex = also a brand, and a confusing one. European PYREX cookware is borosilicate glass. Kitchen pyrex sold in the United States is tempered soda-lime glass, says Iowa State University Extension. Same word, two different materials.

The rule is the same for all three. Read the product page for the word "borosilicate". Do not go by the brand name. If the listing only says "glass", assume soda-lime.

What Temperature Range Can Borosilicate Glass Handle?

SCHOTT rates its BOROFLOAT 33 borosilicate at 450 degrees C for long use and 500 degrees C for short use. Its transformation temperature is 525 degrees C, measured to ISO 7884. That is the raw sheet glass, as used in a lab or an oven door. A kitchen product is always rated lower. The limit comes from the thickness, the shape and the fittings, not from the glass alone.

Our 5-litre dispenser is rated -20 to 150 degrees C. For a dispenser, that is the range to go by. It covers chilled sherbet from the fridge and hot chai from the kettle. It does not mean you can pour boiling water into a cold jar.

Thermal shock is a different number from temperature. Shock is the size of a sudden jump, not how hot the glass gets. Corning tested flat glass plates. It heated them in an oven, then dropped them into cold water. Its borosilicate plates, Pyrex 7740, took a jump of 150 to 180 degrees C. Its soda-lime plates took only 50 to 65 degrees C. Corning calls these figures approximate. That is why a tumbler from the fridge can crack when hot chai hits it. A lab beaker does not.

How to Identify Borosilicate Glass

The only sure way to identify borosilicate glass at home is the label. Look for the word borosilicate on the box or the listing. The other clues below are weak.

• Check the label: Makers of borosilicate glass usually say so, because it is a selling point. If it just says glass, assume soda-lime.
• Clarity test: A weak clue. Thick soda-lime glass often shows a faint green edge. Borosilicate usually looks clearer. But some soda-lime glass is very clear too.
• Weight test: A weak clue. Corning lists borosilicate at a specific gravity of 2.23 and soda-lime at 2.47. That is only about 10% lighter, too little to feel by hand.
• Price indicator: A weak clue. A very cheap large glass dispenser is more likely soda-lime. But price never proves the glass type.

Saran Reddy

Founder, InstaCuppa | Building kitchen tools that give busy Indian moms their time back