A melting point is the temperature at which a substance changes from solid to liquid. If you want to melt or cast metal, that melting point determines the temperature your melting furnace needs to reach and which crucible you need.
What happens at the melting point of a substance?
At the melting point, a substance transitions from the solid to the liquid phase. If you add heat to a solid, the temperature rises until the melting point is reached.
At that point, the temperature remains stable for a while, even if you continue to heat it. For example, ice that you heat stays at 0 degrees until it has completely melted. All the added energy at that moment goes into melting, not into further heating. That energy is called the latent heat of fusion.
You can see this clearly with metals: the metal collapses and becomes liquid, while the temperature remains at the melting point.
At the melting point, the solid and liquid forms of the substance are in equilibrium. If you then cool the liquid again, it solidifies at exactly the same temperature.
The melting point and the freezing point of a pure substance therefore coincide. This transition is called a phase transition: a physical process in which the substance itself does not change, only its state.
What is the difference between melting point and boiling point?
The difference between melting point and boiling point lies in the phase transition achieved. At the melting point, a substance goes from solid to liquid. At the boiling point, that same substance goes from liquid to gas, and that is always higher.
Water is the clearest example. It melts at 0 degrees and boils at 100 degrees. Between these two values, water is liquid; below it, it is ice, and above it, water vapor.
This distinction is important for the blacksmith. If you only know the melting point of a metal, you do not yet know at what temperature it will evaporate again.
What does the melting point depend on?
The melting point depends on the strength of the bonds in the substance and on the pressure. The stronger the atoms in the crystal lattice hold each other, the more heat is needed to break them apart.
Strong bonds therefore result in a high melting point. Tungsten has the strongest bonds of all metals and thus the highest melting point.
Pressure also plays a role. The melting point is standard at a pressure of 1 atmosphere. If the pressure deviates from this, the melting point shifts a little, and it is referred to as melting temperature. This effect is much smaller than with a boiling point, and in the workshop, you almost always work at normal atmospheric pressure.
Purity is the third factor. A pure metal has a sharp, fixed melting point. Impurities usually lower the melting point: road salt that melts ice below 0 degrees is an everyday example. A mixture or alloy, on the other hand, melts over a whole range.
The melting point is also a characteristic property of a substance. Because a pure substance always melts at the same temperature, the melting point shows how pure a material is.
The melting points of frequently used metals
The melting points of frequently used metals vary widely. Some metals already melt at a few hundred degrees, while others only melt well above three thousand.
If you work with melting and casting, these values determine what equipment you need. Below are the melting points of the metals you most often encounter in the workshop, at a pressure of 1 atmosphere.
| Metal | Melting Point |
| Tin | 232 °C |
| Lead | 327 °C |
| Zinc | 420 °C |
| Aluminium | 660 °C |
| Silver | 962 °C |
| Gold | 1064 °C |
| Copper | 1084 °C |
| Iron | 1538 °C |
| Tungsten | 3422 °C |
| Brass | 900°C |
| Bronze | 870°C |
| Zinc | 419.5 °C |
Metals with a low melting point, such as tin and lead, are often used for soldering and casting into small forms. They liquefy quickly and require little energy.
Silver, gold, and copper are close together, all around 1000 degrees, and require significantly more heat. Iron and steel are so high that they are usually not worked in liquid form but forged in a forging furnace. To ensure that a metal is truly liquid, measure the temperature during heating instead of relying on visual assessment.
What is a melting range for alloys?
A melting range is the temperature range in which an alloy melts. Unlike a pure metal, an alloy does not have a sharp melting point.
It melts between two temperatures: the solidus, at which it just begins to melt, and the liquidus, at which it is completely liquid. Between these two values, the solid and liquid phases coexist. This makes an alloy more difficult to cast than a pure metal, as you have to monitor an entire range.
Brass usually melts between 900 and 940 degrees, depending on its composition. Bronze is in a similar range, between 900 and 1000 degrees. One type of alloy is an exception: a eutectic mixture does have a fixed melting point, just like a pure metal.
If you know the melting range of your alloy, you know what temperature to maintain. This way, you cast cleanly, without overheating the metal or allowing it to solidify too early.
How to choose the right melting furnace for your project
The melting point determines what equipment you need to melt a metal. Your melting furnace must be able to easily reach the metal's temperature, and your crucible must be able to withstand that heat. A crucible that is chosen too tightly can crack or contaminate the metal.
Always maintain a margin above the melting point, because a metal only casts cleanly when it is completely liquid and thoroughly heated.
For aluminum with a melting point of 660 degrees, a lighter setup is sufficient than for copper or bronze, which go towards 1000 degrees. So, choose your equipment based on the metal you cast most often.
At Parrot Shopping, you'll find melting furnaces and crucibles with temperature ranges suitable for these metals, so you can get started safely and cleanly. If you're unsure which setup suits your work, we'd be happy to advise you, as we aim to be your guide in the blacksmithing craft.
