Blueback and other poster papers are designed for a specific job: fast, low-cost prints that are pasted up, displayed for a campaign and then replaced. The blue or grey backing on blueback stops old posters showing through when new ones are pasted over them. These papers are not meant to last indefinitely, and that should shape any decision about coating them.
Is a coating worth it?
For a typical two-week billboard or bus shelter cycle, usually not. The added cost and handling time are hard to justify on a print that is designed to be pasted over. A coating starts to make sense when the poster will stay up longer than usual, when it is in a sheltered position where rubbing and graffiti are more of a problem than weather, or when the customer wants a consistent sheen across a set.
Be clear with customers that coating a light, uncoated poster paper does not turn it into a durable outdoor substrate. The paper itself still softens when wet and can tear. If the brief really needs a long life outside, a synthetic paper, banner or vinyl may be the better choice. Our page on indoor vs outdoor use covers how to frame that conversation.
Coating and paste-up
Wet paste-up raises particular points:
- Poster papers expand when pasted. A coating applied before posting may crack or wrinkle as the paper moves. Test a coated sheet with your usual paste and brush.
- Some sites paste over the face of the poster as well as behind it. A coating may change how paste wets the surface.
- Removal practice matters. If the next crew strips posters rather than pasting over them, check that a coated poster still comes away cleanly.
Ink and paper
Poster papers are printed on most ink technologies, from aqueous pigment and dye through eco-solvent, latex and UV. Light, absorbent papers can draw a liquid coating into the sheet, which may leave a blotchy finish or show through as darker patches. A thin first coat sometimes helps. Dye-based prints carry an extra risk of colour movement under a solvent coating; see our dye inks page.
Indoor posters
Indoors, on satin or photo-based poster stocks, coating is more often worthwhile, for instance on retail and cinema posters that are handled or kept as display pieces. Our posters page looks at those jobs in more detail.
Whether a poster run is worth coating is often a commercial call as much as a technical one. Ring 01252 624 411 and we can help you weigh it up, or post us a printed sheet to look at.