Melting temperatures of alloys
Comparative melting temperature table for gold, silver, and platinum. Calculate melting points and workshop casting alloys accurately on GoldPrice24.
At a glanceMelting temperatures of precious metal alloys are fundamental physical constants in jewelry manufacturing, horology, and foundry operations in Switzerland. Working at improper temperatures leads to casting porosity, zinc burn-off, excessive grain growth, or structural brittleness. This technical guide provides comprehensive reference tables of melting ranges for gold, silver, platinum, and palladium.
Solidus vs. Liquidus: Understanding the Melting Interval
Pure elemental metals (such as 24k fine gold at 1,064.18 °C) change states instantly at a single sharp temperature. By contrast, virtually all commercial precious metal alloys exhibit a melting range bounded by two critical points:
- Solidus temperature: The temperature at which the alloy begins to melt. Below this point, the metal is 100% solid.
- Liquidus temperature: The temperature at which the alloy becomes completely liquid. Above this point, no solid crystals remain.
- Pasty range (Solidification interval): The temperature span between Solidus and Liquidus. A narrower interval ensures cleaner, denser castings.
Comprehensive Melting Point Reference Table for Precious Metals
The following table reflects official metallurgical standards used by the Swiss watchmaking and jewelry industry (NIHS / ISO):
| Metal / Alloy Designation | Fineness (‰) | Visual Shade / Tone | Solidus Temp (°C) | Liquidus Temp (°C) | Recommended Casting Temp (°C) |
|---|---|---|---|---|---|
| Fine Gold (24k) | 999.9‰ | Pure rich yellow | 1,064 °C | 1,064 °C | 1,120 – 1,150 °C |
| 18k Yellow Gold (2N) | 750‰ | Light Swiss yellow | 885 °C | 905 °C | 980 – 1,020 °C |
| 18k Yellow Gold (3N) | 750‰ | Standard rich yellow | 880 °C | 900 °C | 970 – 1,010 °C |
| 18k Rose Gold (4N) | 750‰ | Classic rose | 890 °C | 910 °C | 980 – 1,020 °C |
| 18k Red Gold (5N) | 750‰ | Watchmaker red gold | 885 °C | 895 °C | 960 – 1,000 °C |
| 18k White Gold (13% Pd) | 750‰ | Natural white (nickel-free) | 1,050 °C | 1,100 °C | 1,180 – 1,230 °C |
| 18k White Gold (Nickel) | 750‰ (restricted use) | Bright white | 920 °C | 950 °C | 1,020 – 1,060 °C |
| 14k Yellow Gold (585) | 585‰ | Medium yellow | 830 °C | 880 °C | 950 – 990 °C |
| 9k Yellow Gold (375) | 375‰ | Pale yellow | 880 °C | 950 °C | 1,010 – 1,060 °C |
| Fine Silver (999) | 999‰ | Brilliant white | 961.8 °C | 961.8 °C | 1,020 – 1,060 °C |
| Sterling Silver (925) | 925‰ | Standard silver | 893 °C | 899 °C | 960 – 1,000 °C |
| 800 Silverware | 800‰ | Table silverware | 780 °C | 820 °C | 880 – 930 °C |
| Fine Platinum (999.5) | 999.5‰ | Steel grey | 1,768 °C | 1,768 °C | 1,850 – 1,900 °C |
| Platinum 950 (Pt/Ru) | 950‰ | Bright white | 1,750 °C | 1,775 °C | 1,840 – 1,880 °C |
| Palladium 950 | 950‰ | Silvery white | 1,530 °C | 1,555 °C | 1,620 – 1,660 °C |
Practical Casting Superheat Rules
Metal should never be poured at its bare Liquidus temperature. Contact with the cooler crucible lip and mold instantly cools the stream. Jewelers apply a superheat of 60 °C to 100 °C above Liquidus to guarantee complete filling of fine details.
Stepped Soldering Temperatures
When assembling complex multi-part jewelry, bench jewelers solder in descending thermal stages so earlier joints do not re-melt:
1. Hard (Extra-tough) Solder: Flow point ~790–820 °C for initial structural framework joints.
2. Medium Solder: Flow point ~740–770 °C for bezels and decorative settings.
3. Easy (Soft) Solder: Flow point ~700–730 °C for clasps and final sizing joints.
Frequently Asked Questions (FAQ): Melting Temperatures
Why can't platinum be melted with a standard propane/air torch?
A propane-air torch peaks at 1,350 °C, far below platinum's 1,768 °C melting point. Platinum requires an oxy-hydrogen (water gas) torch or an induction furnace.
Which precious metal alloy has the lowest melting point?
800 silver melts at just ~780 °C (Solidus) due to its 20% copper content, which is very close to the silver-copper eutectic point (779 °C at 28% Cu).
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