Spray powder creates a small air gap between freshly printed sheets so wet ink is less likely to transfer to the back of the next sheet. It is not a drier. The correct objective is the minimum amount that prevents set-off without leaving excessive powder, dust, or finishing risk.
Confirm four variables
| Variable | Why it matters |
|---|---|
| Stock and surface | Thin, coated, heavy, board, and non-absorbent stocks behave differently in the pile |
| Ink film and coverage | Heavy solids and multiple colors raise set-off risk |
| Delivery condition | Speed, pile height, air, static, and dwell time change the required separation |
| Finishing | Residual powder can affect lamination, coating, foil, adhesive, or appearance |
Fine powder may give a more subtle appearance but can become airborne more easily. Coarser powder creates more separation but can leave a more visible residue. Select by the complete job, not only by mesh or particle size.
Controlled trial
- Clean the hopper, routes, nozzles, and filters. Do not mix unknown old powder with new material.
- Run a representative job and inspect powder distribution. Pull samples from the top, middle, and bottom of the pile; check both set-off and surface residue.
- Keep the particle grade and nozzle position fixed while adjusting one variable at a time. Confirm the lowest setting that prevents set-off.
- Before lamination, coating, foiling, gluing, or second printing, remove residual powder as required and test the first finished samples.
Troubleshooting order
| Symptom | Check first | Avoid |
|---|---|---|
| Set-off continues | Ink film/drying, distribution, pile, speed | Adding large amounts of powder without checking drying |
| Visible residue or dust | Quantity, grade, nozzle and hopper condition, extraction | Changing brands without cleaning the system |
| Finishing adhesion failure | Powder removal, grade, and actual finishing condition | Blaming varnish or adhesive before checking residue |
| Clumping or uneven pattern | Humidity, storage, contamination, hopper/nozzle | Adding fresh powder into contaminated material |
Keep powder dry, sealed, and free from contamination. Follow SDS, ventilation, housekeeping, fire-control, and PPE requirements for dust. Start with Ecolon/CY-KP Spray Powder for thin/high-quality color work or MATCH Spray Powder for heavy stock and high-coverage work, then verify on press.