Filtering Gilsonite Varnish for Clean Inks
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Even low-ash gilsonite contains small insoluble particles. Filtration is essential.
Methods
- Bag filters (25–50 µm)
- Cartridge filters for fine polishing
- Settling tanks for coarse removal
Tips
- Filter while hot for lower viscosity
- Change filters regularly
- Inspect samples on a grindometer
Filter selection
| Stage | Filter rating |
|---|---|
| Coarse | 100 µm bag |
| Standard | 25–50 µm bag |
| Polishing | 10 µm cartridge |
Good practice
- Pre-heat filter housings to avoid cooling the varnish.
- Monitor pressure drop; change filters before they blind.
- Keep filter residue records – rising residue can indicate a raw material issue.
Safety
Hot varnish and solvents require heat-resistant gloves and proper ventilation.
See ink grade gilsonite. Related: making ink varnish.
Recommended product
Data sheet
Ink & Paint Grade Gilsonite
| Property | Typical value | Test method |
|---|---|---|
| Appearance | Dark brown–black powder | Visual |
| Softening point (R&B) | 150 – 180 °C | ASTM D36 |
| Ash content, max | 3 % | ASTM D3174 |
| Moisture, max | 1 % | ASTM D95 |
| Solubility in toluene, min | 99 % | ASTM D2042 |
| Particle size | 200 – 600 mesh | Sieve |
| Typical dosage | Ink varnish: 20–40 % in oil | |
| Packing | 25 kg paper bags with PE liner, palletized. | |
Typical values. The final specification is confirmed in the COA of each shipment.
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