Spot UV: what it is and when it works

UV varnish is a liquid coating that stays wet until it is exposed to ultraviolet light, when it cures almost instantly into a hard, clear, glossy layer. Spot UV applies that varnish only where your artwork says, usually by screen printing or with a coating plate, after the sheet has been printed and laminated. The result is a gloss layer sitting on top of the surface.

The effect depends entirely on contrast. On matt or soft-touch lamination, a glossy logo reflects light while the rest of the box stays flat, so the design appears and fades as the box moves. On gloss lamination there is almost no contrast, so spot UV adds little. On uncoated or kraft board the varnish soaks in and gives a dull, uneven result.

Spot UV can be flat or raised. A standard coat is thin and mostly visual. Raised or tactile spot UV lays down a thicker deposit that you can feel, which suits patterns, dots and textures. Tone-on-tone designs are popular: a black box with matt lamination and a gloss black pattern that shows only when light catches it.

Registration matters. The varnish is applied in a separate pass, so there is a small tolerance between print and varnish. Spot UV that must sit exactly over a printed logo should be designed with that in mind, and very thin lines or small text in varnish can fill in or look uneven.

A hard varnish is less flexible than film where board bends. It can crack across creases and turn-in edges, so keep it off score lines, glue areas and the edges of rigid-box wraps. On soft-touch lamination, the varnish must be one made to bond with that coating, or it may not adhere properly.