Pad Printing Additives
Industrial Thinners, Retarders, Hardeners & Auxiliaries
Ink transfer efficiency, edge sharpness, and adhesion rely on exact ink adjustment. We supply the complete Coates Screen Inks range of aromatic-free thinners, temperature-compensating retarders, reactive hardeners, and specialised adhesion promoters engineered to stabilise viscosity and optimize cycle times.
Thinners (Diluents)
Reduces ink viscosity to optimal pad transfer levels while controlling solvent flash-off speed from the silicone pad.
- Additive A: Universal benchmark standard thinner (Factor 1.0)
- Additive C & D: Fast-drying thinners for high-speed cycle runs
- VD 10: Mild, non-aggressive thinner for stress-crack sensitive plastics (PC/PMMA)
- VD 20 / VD 60: Medium to standard evaporation thinners for 1- & 2-pack systems
Retarders
Slows down solvent evaporation to prevent dry-in on the cliché plate during warm shop-floor ambient temperatures or fine-line printing.
- TPV: Standard universal retarder (Evaporation Factor 4.0)
- TPV 2: Very slow retarder for hot shop floors and intricate graphics (Factor 10.0)
- TPV 3: Extra-slow retarder for high-temperature cycles and slow manual operations (Factor 18.0)
- TPV 8: Special retarder formulation for TP 300 and TP 218 series
Reactive Hardeners
Polyisocyanate and chemical curing agents that cross-link with 2-component ink ranges to achieve industrial chemical and scratch resistance.
- TP 219: Standard hardener for TP 218, TP 300, TP 340 & TP 400 (Ratio 10:1 or 4:1)
- TP 219/VCH: Enhanced moisture & chemical resistant hardener for glass and metals (TP 318)
- TP 219/N-00: Fast-reacting aliphatic hardener for exterior lightfast applications
- Pot Life: Typically 8 to 12 hours once incorporated into mixed ink
Primers & Auxiliaries
Specialty chemical modifiers for difficult surface energy requirements, finish adjustments, and pad release troubleshooting.
- Adhesion Promoter GL: Added to 2-component inks for direct adhesion to glass & chrome
- Additive U: Flow agent improving ink levelling and eliminating pad pinholes/orange peel
- Matting Powder STM: Delustring additive to convert high-gloss inks to semi-gloss or satin
- Cleaning Solvents: Dedicated cliché and silicone pad washing agents
Solvent Evaporation Rate & Application Guide
Relative evaporation speeds compared against standard thinner Additive A (Factor 1.0). All products are free of aromatics and cyclohexanone.
| Solvent / Additive | Type | Evaporation Rate | Speed Factor | Recommended Applications & Inks |
|---|---|---|---|---|
| Additive C | Thinner | Very Fast | 0.25 | High-speed multi-colour cycle runs; rapid pad release |
| Additive D | Thinner | Fast | 0.5 | Cold workshop environments; accelerating tack speed on standard plastics |
| VD 10 | Thinner | Fast | 0.5 | Mild solvent power; prevents stress cracking on Polycarbonate (PC) & Acrylic |
| Additive A | Thinner | Medium (Standard) | 1.0 | Industry standard universal thinner for all 1-pack and 2-pack ink ranges |
| VD 20 / VD 60 | Thinner | Medium to Standard | 1.0 | Universal thinners with balanced solving power for TP 300, TP 218 & TP 400 |
| TPV | Retarder | Slow | 4.0 | Standard retarder; keeps clichés open during short stops or ambient shop warmth |
| TPV 2 | Retarder | Very Slow | 10.0 | Summer workshop conditions; intricate halftones and ultra-fine line graphics |
| TPV 3 | Retarder | Extra Slow | 18.0 | High-temperature industrial environments and slow manual printing machines |
| TPV 8 | Retarder | Slow (Special) | 4.5 | Specifically formulated for Coates TP 300, TP 218, and TP 340 series |
Experiencing ink drying in the cup or static cobwebbing?
Our Sunbury-on-Thames technicians can identify the exact ratio of thinner, retarder, or anti-static agent needed for your shop-floor environment.
Ask a Consumables SpecialistFrequently Asked Questions: Pad Printing Additives & Hardeners
What is the difference between a pad printing thinner and a retarder?
A thinner (diluent) such as Additive A or VD 10 reduces ink viscosity to approximately 4,000–8,000 mPa·s, allowing the ink to cleanly fill the plate etch and release from the silicone pad. A retarder (such as TPV or TPV 2) has a significantly slower evaporation rate (Speed Factor 4 to 10). It is blended with the thinner (typically 5%–10% of total solvent addition) to prevent ink from drying prematurely in the cliché etch during warm ambient temperatures or fine detail runs.
Which thinner prevents stress crazing and cracking on Polycarbonate (PC) and Acrylic?
Thinner VD 10 is specially formulated with mild, non-aggressive solvent components. Standard aggressive thinners can attack the surface tension of unstressed Polycarbonate (PC) or PMMA (acrylic glass), resulting in micro-crazing or spider-web cracking. VD 10 provides smooth viscosity adjustment while preserving polymer surface integrity.
Which hardener should be mixed with TP 218, TP 318, and TP 400?
For standard chemical and abrasion resistance on 2-pack systems (TP 218 and TP 400), use Hardener TP 219 at a ratio of 10:1 by weight (10 parts ink to 1 part hardener). For glass, glazed ceramics, and plated metals using TP 318, Hardener TP 219/VCH is recommended at a 4:1 or 10:1 ratio depending on substrate requirements to maximise water-bath and solvent wipe resistance.
What is the pot life of 2-component pad printing ink after adding hardener?
Once Hardener TP 219 or TP 219/VCH is stirred into the ink, the usable pot life is typically 8 to 12 hours at 20°C. In sealed ink cup systems, viscosity remains stable for the duration of the working shift. After pot life expiration, the ink may remain liquid but will lose chemical cross-linking and substrate adhesion capabilities.
How do I eliminate pinholes, bubbling, or "orange peel" in the ink deposit?
Surface flow defects are usually caused by excessive ink viscosity, rapid surface drying, or surface tension mismatch between the pad and substrate. Adding 1% to 2% Additive U (Flow Agent) lowers ink surface tension, facilitates smooth levelling, and prevents micro-voids and pinholing in solid print areas.