Gilsonite for Newspaper (Coldset) Inks
Coldset news inks dry by absorption into porous newsprint, not by evaporation or oxidation. They need good colour strength, low cost and clean printing.
Why gilsonite suits news ink
- Inexpensive way to increase colour strength
- Helps hold carbon black in the oil
- Reduces rub-off by binding pigment
- Improves set-off resistance
Formulation outline
- Carbon black: 15–20%
- Gilsonite varnish: 20–40%
- Mineral or vegetable oil
- Additives (wax, anti-misting agents)
Performance tips
- Use low-ash gilsonite to prevent roller wear
- Filter varnish carefully
Why news inks are special
Newsprint is absorbent and inexpensive, and coldset presses run fast. News inks must set quickly by absorption, give strong black and keep cost low.
How gilsonite helps
- Adds black colour strength economically
- Binds carbon black into the oil phase
- Reduces rub-off on readers’ hands
- Gives good ink transfer at high speed
Quality targets
| Property | Why |
|---|---|
| Optical density | Strong print |
| Tack | Clean transfer, no picking |
| Rub resistance | Clean handling |
| Misting | Clean pressroom |
See ink grade gilsonite and making ink varnish.
Recommended product
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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