Formulating Facing Sand with Gilsonite
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Facing sand is a richer sand mixture placed directly against the pattern to give a better casting surface.
Typical components
- New silica sand or fine sand
- Bentonite
- Higher level of carbon additive (gilsonite)
- Water
Benefits
- Superior surface finish where it matters
- Reduced overall additive use compared with enriching the whole system
Tips
- Keep facing sand thickness consistent
- Ensure good bonding to backing sand
- Monitor gas evolution on thin sections
Example facing sand mix
| Component | Typical share |
|---|---|
| New fine silica sand | 50–70 % |
| System sand | 20–40 % |
| Bentonite | 6–8 % |
| Gilsonite | 0.8–1.5 % |
| Water | to compactability |
Application
Ram or squeeze facing sand against the pattern in a 20–50 mm layer, then fill with backing sand.
When to use
Large castings, critical surfaces or customers with strict surface roughness requirements.
Recommended product
Data sheet
Foundry Grade Gilsonite
| Property | Typical value | Test method |
|---|---|---|
| Appearance | Black powder | Visual |
| Particle size | 100 – 300 mesh | Sieve |
| Volatile matter | 55 – 75 % | ASTM D3175 |
| Ash content, max | 5 % | ASTM D3174 |
| Moisture, max | 1 % | ASTM D95 |
| Softening point (R&B) | 150 – 200 °C | ASTM D36 |
| Typical dosage | 0.3 – 1.0 % (iron) | |
| Packing | 25 kg bags palletized; 1 MT jumbo bags for blending plants. | |
Typical values. The final specification is confirmed in the COA of each shipment.
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