Cast Silver Bars, also known as silver ingots, are produced by melting refined silver and pouring it into molds followed by controlled solidification. Unlike minted bars, cast silver bars retain a natural cast surface with shrinkage marks, cooling lines, and a matte finish.
They are widely used for investment bullion, industrial raw material, central bank and vault storage, and refinery trade.
Purity & Grade Classification
Cast silver bars are produced from refined silver, not doré material.
| Grade | Silver Content | Fineness |
|---|---|---|
| Investment Grade | ≥ 99.9% Ag | 999 |
| High-Purity Grade | ≥ 99.99% Ag | 999.9 |
| Ultra-Pure (Special) | ≥ 99.999% Ag | 999.99 |
✔ 999 fine is the global bullion benchmark
✔ 999.9 is commonly used for electronics and advanced industries
Chemical Composition
| Element | Typical Content |
|---|---|
| Silver (Ag) | 99.9 – 99.99% |
| Copper (Cu) | < 0.05% |
| Lead (Pb) | < 0.01% |
| Zinc (Zn) | Trace |
| Gold (Au) | ppm-level |
| Sulfur (S) | Trace |
Key Physical Properties
| Property | Typical Value |
|---|---|
| Density | 10.49 g/cm³ |
| Melting Point | 961.8 °C |
| Electrical Conductivity | ~105% IACS |
| Thermal Conductivity | ~430 W/m·K |
| Reflectivity | ~95% |
| Magnetism | Non-magnetic |
| Corrosion Resistance | Excellent (except sulfur tarnish) |
Mechanical Properties
Cast silver bars exhibit annealed (soft) silver behavior due to slow cooling.
| Property | Typical Value |
|---|---|
| Hardness | 25 – 30 HV |
| Tensile Strength | ~170 MPa |
| Yield Strength | ~55 MPa |
| Elongation | 40 – 45% |
| Brittleness | Very low |
Metallurgical Structure & Behavior
• Face-centered cubic (FCC) crystal structure
• Coarse grains due to slow cooling
• Uniform single-phase silver
• Minimal porosity when properly cast
✔ Excellent ductility
✔ Stable at room temperature
Refining & Processing Properties
Feedstock: Electrorefined silver cathodes or refined silver powder
Casting Process:
• Controlled melting (induction or resistance furnace)
• Slag removal and degassing
• Mold pouring (graphite or steel molds)
• Controlled cooling
• Trimming, cleaning, assaying, and hallmarking
Available Forms & Sizes
Common Shapes:
• Rectangular ingots
• Trapezoidal “Good Delivery” bars
• Brick or loaf-shaped bars
Standard Weights:
• 250 g, 500 g, 1 kg, 5 kg
• 15 kg (LBMA)
• 1,000 troy oz (COMEX)
Applications
Investment: Long-term bullion holding, inflation hedge
Industrial: Electronics, solar, alloy production
Trade: LBMA & COMEX vaults, refinery feedstock
Advantages
✔ Lower premium than minted bars
✔ High purity and homogeneity
✔ Cost-efficient production
✔ Ideal for bulk storage
✔ Accepted worldwide
Limitations
⚠ Rough surface finish
⚠ Lower aesthetic appeal than minted bars
⚠ Softer than alloyed silver
⚠ Less divisible in large weights
Cast vs Minted Silver Bars
| Feature | Cast Bars | Minted Bars |
|---|---|---|
| Surface Finish | Rough / matte | Smooth / polished |
| Production Cost | Lower | Higher |
| Premium | Lower | Higher |
| Aesthetic Value | Lower | Higher |
Why Choose Cast Silver Bars (Ingots)
Cast silver bars are preferred when maximum silver weight at the lowest premium is desired. They are ideal for bulk investment, industrial remelting, and long-term vault storage, offering unmatched efficiency and global acceptance despite their raw surface appearance.