Glass Melting Point? (Charts & 18 Things U Should Know)

Does glass melt? Can we melt glass by heating it? If so, why do we use glassware for heating in the oven? What are the thermal properties of glass? Does heat transfer in glass molecules evenly?

Can we turn glass into liquid?

If you are struggling to find out the answers to the above questions, this post is for you.

Here you will learn everything relating to melting and heating glass.

Let’s know the answer to what is glass melting point?

The melting temperature of glass depends on the composition of glass, moisture in glass content, and type of glass. Glass is molded at the temperature of 1400C to 1600C (2552-2912F). When heating, It liquifies a bit and the rest of the glass remains solid.

After melting, the liquid attains the shape of the mold in which it is poured. Glass passes through the softening stage before transitioning to a rubbery texture. In its melted form, it looks waxy. Once cooled quickly, it can break easily. 

Keep scrolling your eyes to know everything about glass melting points.

Must Read: What happens if you swallow glass?

Does Glass Melt Actually

Melting is the process in which a solid substance is turned into liquid. To do so, the substance is heated or its temperature is increased. For example, ice melts into the water by increasing temperature.

Does glass melt on heating? No, it does not melt, it liquifies gradually and goes through a transition phase. In this phase, it changes its shape after melting and attains the shape of the mold you put in. 

If by melting you mean changing into liquid, it does, but for a few moments. It again turns back into the shape of the mold. It does not melt as a liquid but softens as it flows when heated. When it becomes soft it can be molded into any desired shape.

What is Glass Melting Point

From the above discussion, it is clear that glass does not melt. It liquifies and becomes softened gradually when heated. The temperature when glass actually turns into liquid depends on the composition of glass. 

What is the melting point of glass? Glass liquifies or melts at high temperatures from 1400C to 1600C. This temperature varies with the composition of glass. As glass is made up of different substances like lime, soda, and sand. Moreover,  different types of glasses have different melting points. 

Boiling Point of Glass

Glass is considered a unique homogeneous substance. The reason is that, unlike other homogeneous materials, heat does not distribute evenly in silicate. Instead, a part of glass receives more heat and becomes hotter. It melts at an even lower temperature than the boiling point of that material. 

After experiments, it is concluded that the boiling point of pure silicate glass is 2,230degree Celsius (4046 degrees Fahrenheit). The hottest recorded temperature of silicate glass in the experiment was 1868.7 degrees Celsius.

The surprising fact in this experiment was that heat was not transmitted equally in the glass. They performed another experiment. In which they induced an electric field to decrease the temperature of glass at which it becomes softened. They found that the electric field reduces the temperature at which glass gets softened to a few hundred degrees. They name this phenomenon as  “eclectic field-induced softening”.

To verify this, they put pieces of glass in a furnace and induced 100 to 200V as both AC(alternating current) and DC( Direct Current). Surprisingly glass becomes more than a thousand degrees hotter near the positive side as compared to the rest of the glass. It turned out that only a part of the glass was heated and the rest was solid.

Soft Glass Melting Point

Soda-lime is the main component in the composition of soft glass. This type of glass is widely used in windows and is easily breakable. It is also used in artistic sculptures, vases and layer fusing. It can break when it is cold after heating. It is malleable in hot form. 

Soft glass has a low melting point or softening point but a high coefficient of thermal expansion. For this reason, it is highly susceptible to thermal shock. It contains no metal and it is a pure form of glass. That’s why it’s weaker. 

Borosilicate Glass Melting Point

Borosilicate glass was first manufactured by German glassmaker Otto Schott. It is composed by mixing melted boric oxide, silica sand, soda ash and alumina. It is more difficult to manufacture than traditional glass because of its high melting point. 

What is the melting point of borosilicate glass? Borosilicate glass is also named hard glass. It melts at a high temperature of about 3000F or 1648C. This type of glass is widely used in glass blowing by bead makers. It requires new techniques for industrial production.

what is glass melting point

Soda Lime Glass Melting Point

A glass of any kind is a “ frozen liquid”, so there is no exact melting point. Soda-lime glass is composed of 73% SiO2 – 15% Na2O − 7% CaO − 4% MgO − 1% Al2O3. The chemical ordering in soda-lime glass is very strong. Each silicon atom forms a bond with 4 oxygen atoms and 4 oxygen atoms share a bond with two silicon items.

This type of glass melts easily at a relatively lower temperature than hard glass. It melts at 1000 degrees Celsius. Whereas it turns into vapors around 3427-degree celsius.

Other heat-related properties of soda-lime glass are given in the table.

Thermal Properties of Soda Lime Glass:

Thermal Properties Value
Refractive index, n1.46
% Transmittance (at 1 µm)70–80
Density, ρ (g/cm3)2.5
Thermal conductivity, k (W/m·°C)1.06
Specific heat, CP (J/g·°C)0.87
Softening point (°C)700
Melting temperature, TM (°C)1000
Vaporization temperature, TV (°C)3427

Quartz Glass Melting Point

Unlike its name, quartz is not glass. Instead, it is a mineral with a chemical formula SiO2. It is a form of crystalline solid like other minerals. It has a certain number of atoms that are arranged in a repeated pattern. Due to this repeated pattern, they attain the shape of the crystal. On the other hand, glass is a form of non-crystalline solid.

Quartz glass is relatively harder as it is mineral, not glass. It has a melting point of 1250 degrees celsius. Due to its brittle texture, it requires a high temperature to melt. Moreover, the thermal expansion coefficient of quartz is very low.

Pyrex Glass Melting Point

Pyrex is borosilicate hard glass. This makes it highly temperature resistant. It is widely used in the manufacturing of kitchenware that we use in the microwave. The melting point of type 7740 Pyrex is 1,510°F or 820°C.

The kitchenware made of pyrex will never melt unless heat exceeds this limit. However immediate temperature change can affect kitchenware. So preheat the glass,  jugs or cups made of pyrex before exposing it to a sudden temperature increase.

Pyrex is a widely used low expansion glass.  The melting point of pyrex is between 820C to 1250C. The melting temperature varies with the thickness of the glass.

Tempered Glass Melting Point

Tempered glass is the toughest type of glass and is not easy to break. It has wide application for safety purposes. It is manufactured by heating and then cooling readily. That’s why it has a different structure and breaks differently.

The tempered glass melts between 1100 and 1300 degrees Fahrenheit. After heating, it is cooled readily using high-pressure cold air. After cooling, it hardens under stress. When it breaks it turns into Peebles rather than splinters. It needs four times more force to break it than needed for untreated glass.

Lead Glass Melting Point

Lead glass is also named crystal. In this type of glass, lead is used instead of calcium. This glass variety contains 18-40% PbO. It is widely used in glassware, ornaments, jewelry, optical lenses, and sculptures. 

Lead glass is not easy to melt. A temperature between 1350 degrees Celcius to 1500 degrees Celcius is required to melt this glass. This procedure is carried out in an electric furnace where it undergoes heat and electricity.

Glass Wool/Fiber Glass  Melting Point

Glass wool is also named fiberglass. It is recycled material from bottles and other glassware. It’s not the glass itself, it’s reinforced plastic in which glass fiber is mixed. 

The melting point of glass wool is 1450 degrees Celsius. After melting it is passed through spinners where it is turned into glass fibers. These glass fibers are mixed with plastic and have wide applications in synthetic items.

Glass Softening Temperature 

When heating, glass does not turn directly into the liquid. It first turns softer before becoming liquid. This process is called the transition stage of glass. The transition temperature of glass varies with the type of glass, the composition of glass, and moisture content in it.

Overall the softening temperature of glass ranges from 140 degrees Celcius to 370degree Celcius. It varies with the type of glass and moisture content in its composition. When it gets softened, it turns from a solid state to a soft rubbery state. This temperature is lower than the melting point of glass.

Melting Point of Glass Vs Steel

There are countless varieties of steel. We can’t make the right guess about the melting temperature of steel without taking specific variety into consideration. Steel takes time and more heat before starting the heating process actually. Different alloys of steel have variable temperature tolerance ranges and melting points.

The melting point of the glass is much lower than steel. All glass melts below or near 1000 degrees Celcius, but steel takes more energy to preheat and melts above 1500 degrees Celcius. However, this temperature varies in different alloys of steel.

Comparison Table Melting Point of Metal Vs Glass

MetalMelting Point CelsiusMelting Point Fahrenheit
Admiralty Brass900 – 9401650 – 1720
Brass, Red10001832
Gold, 24k Pure10631945
Iron, Wrought1482 – 15932700 – 2900
Stainless Steel15102750

What Temperature Does Glass Melt at Fahrenheit?

The glass melts at 2552-2912 degrees Fahrenheit. It first gets softened and then turns into liquid before melting. This is known as the transition stage of glass.

What is Glass Melting?

Glass can’t be melted,  it is molded. It is molded at very high temperatures. It melts around 1400 degrees Celsius to 1600 Degree Celsius depending on the composition of glass. The process of melting or molding glass is carried out in a special furnace under thermal control.

Does Glass Melt in Fire?

Yes, glass can meltdown in the fire. In this process, a part of glass turns into liquid and the rest remains solid. Unlike homogeneous substances, heat is not distributed evenly in the glass. 

Can I Melt Glass in My Oven?

No, you can’t melt glass in the oven. As glass requires 1400 C to 1600C to melt. The oven is designed to reach 200 C to 250C only. So, they can’t melt glass. That’s why you can use glassware in ovens without worrying about breakage.

What Temperature Does Glass Melt Celsius?

The melting point of glass in celsius is between 1400C to 1600C. Glass first softens at 800 to 1000C and then liquifies. It does not melt directly and only a part of the glass melts first. The rest of the glass remains solid.

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Final Words

We’re at the end of an informative post about the melting point of glass. This material appears to be delicate enough. One may think it would melt easily at low temperatures. But it requires a high temperature to melt.

Moreover after melting it can fracture easily. That’s why slow cooling is recommended to avoid breakage after heating the glass surface. To end up, Glass has different softening temperature(140C to 370C),  melting temperature( 1400C to 1600C), and boiling temperature(2,230C),