Running 1–3 g/m²: a stable process once it is set up
Coaters are used to 10–15 g/m² of primer, and 1–3 g/m² sounds like something that needs constant attention. It does not: the amount is set by the roller and the primer’s own viscosity, settles at around 1.5 g/m² and stays there.
Because Duoprime® M is applied thin and its viscosity is matched to the roller, the application does not drift the way a thick primer does. Once the line is set up it is one of the least demanding steps on it. This is how to set it up.
- 01
Clean the roller coater, pumps and pan with butyl acetate before the first run, so nothing from the previous primer mixes in.
- 02
Fit a Mitex roller 30–50 and run it in reverse with the doctor blade. Set it for 1–3 g/m²; with the viscosity of Duoprime® M the amount will settle around 1.5 g/m².
- 03
Feed clean, dry melamine — no sanding, no corona.
- 04
Activate with undoped full-spectrum medium-pressure Hg lamps at 500–700 mJ/cm² measured in UVA. Rule of thumb: 10 m/min with 2 × 120 W/cm, 15 m/min with 3 × 120 W/cm.
- 05
Expect the surface to look wet after the lamp. That is normal — oxygen inhibition — and it is exactly what the next coat bonds into. Apply the base coat straight away.
- 06
Check adhesion on the first boards with a cross-cut, then leave the settings alone.
Running it: there is no pot life and nothing hardens in the pan. At a line stop, pump the primer back into the container and restart when you are ready — no discarding, no flushing. Store the primer above 15 °C, away from UV light; it keeps for 12 months unopened.