An underbase places white behind color from the viewing side, helping color stand out on dark or transparent material. It is not always needed: translucent effects may intentionally leave the backing clear.
Print order follows the viewing side
For a typical front-printed graphic, white is printed before color. For reverse printing viewed through clear material, color is usually nearer the clear sheet with white behind it. Confirm the actual layer sequence for the process.
Avoid a white halo
A white backing that extends beyond color can show as a halo. Some workflows choke, or slightly shrink, the backing to account for registration. There is no universal amount; the printer may control it in the production software.
Before production
- Mark areas that should stay transparent.
- Confirm whether the printer generates the underbase or needs a supplied spot separation.
- Follow the required choke and overprint settings rather than enlarging every white shape.