Decorative and Special Effect Coatings

Arcvista coatings are specified for what they make the pack look like. Each grade is formulated to produce a defined optical or tactile result on a printed substrate, applied from an existing coater, flexo unit or screen station, so that the decoration is produced inside the print run instead of in a separate converting step. That is the boundary that defines the range: Arctouch and Arclear are functional finishes, soft-touch feel and protective gloss or matt, while Arcvista exists to create a visual effect that stands in for a separate decoration step such as foil, metallised board or an embossing die.

The drip-off system shows how an effect of this kind is generated. A matt oil-based effect primer is printed from an offset unit in the exact pattern that is to read matt, and a gloss UV overprint varnish is then flooded over the whole sheet from the coater, wet on wet. The two are not chemically reactive with one another. The primer forms a low surface energy film that the higher surface tension varnish cannot wet, so the varnish retracts from the primed areas while it is still open. It does not leave the primer bare: it pulls back into a thin, uneven film that scatters light and reads matt, against the fully levelled gloss everywhere else. Because the pattern is carried by the plate that lays the primer, the contrast needs no register step of its own, and the two products are formulated, supplied and bought as a matched pair. A primer from one supplier and a varnish from another will not hold the contrast reliably.

The other effects follow the same principle, that the mechanism sits in the application as much as in the pigment list. Structure coatings are cured in two stages: a short wave source skins the surface first, then the full cure shrinks the bulk beneath it and the skin wrinkles into a controlled texture, so lamp type, cure sequence and line speed set the texture as firmly as the applied weight does. Pearlescent and interference coatings use platelet pigments that must orient parallel to the substrate surface to develop lustre, so application method and wet film thickness govern the result more strongly than pigment loading does. The patterned optical effect grade lays a matt and gloss contrast down in a fine regular pattern, so the printed area appears to shift as it is tilted, and it is specified as decoration, not as an authentication feature.

Two commercial points are stated plainly. A printed metallic does not reach the specular brilliance of hot foil, cold foil or metallised board, and what it does return depends heavily on substrate smoothness, so a result achieved on cast-coated board will not repeat on a rough recycled liner. The case for a printed effect against foil has to be calculated per job, taking coverage, the number of passes, press speed and waste into account, because the answer changes with the design. Arctic supplies the coating and the application window, and a press trial on the customer press and the production substrate is required before any effect is committed to a production specification.

Matched pairs of matt effect primer and gloss overprint varnish that produce a self-defining matt against gloss contrast through a surface energy difference, with no register step of their own.

Printed silver and gold metallic effects applied from the coater or a flexo unit, offered where an in-line metallic field is wanted and the design and run length support it, without matching the specular brilliance of foil.

Platelet pigment coatings that develop lustre and colour travel when the pigment orients parallel to the surface, for soft pearl and shifting interference finishes.

High film build coatings cured to hold a raised texture, from fine wrinkle structure through to heavy screen-applied relief that adds height on the surface of the sheet.

A fine regular matt and gloss pattern that appears to move as the pack is tilted, produced within the print run rather than by a separate decoration process, and specified as decoration only.

Coatings carrying visible reflective particles, from fine sparkle applied through a high volume anilox to heavy coarse-particle effects applied by screen.

Coatings that absorb ambient light and re-emit it as a visible glow after the light source is removed, used for graphic effect on pack and not as a safety marking.

The figures below are the typical operating window for this range, not a measured result for any one batch. Confirmed values are issued with the Technical Data Sheet and Certificate of Analysis by our laboratory.

The table above is the typical operating window for the range and not a measured result for any one grade. Confirmed values are issued with the Technical Data Sheet and Certificate of Analysis by our laboratory.

Drip-off

Arcvista DO 110 is printed from an offset unit in the matt pattern, normally from the last available ink station, and Arcvista DO 120 is flooded over the whole sheet from the coater immediately afterwards, wet on wet. The pair must run together. The contrast collapses if the primer film is too thin, if the primer is over-powdered, or if the varnish film is heavy enough to bridge the primer instead of retracting over it. Ink sequence, fount chemistry and IR settings all move the surface energy balance, so the pair is trialled with the actual ink set that will run the job. The primer sets by absorption and oxidation, so a non-absorbent laminated or pre-coated surface is treated as a separate trial. Matt and gloss edges are judged on the sheet at press speed, not on a hand proof.

Metallics, pearlescents and glitter

Leafing and platelet pigments need to reach the surface and lie flat, which means enough wet film, a smooth substrate and a cure that does not disturb the film before the pigment has settled. Anilox volume is chosen for the grade, chambers and screens are checked for settling at stoppages, and the coating is stirred back to uniformity before and during the run. Glitter above fine particle size cannot pass an anilox and is screen applied. Brilliance is substrate driven and a printed metallic does not match foil or metallised board, so a result on cast-coated board will not repeat on a rough recycled liner and each substrate is treated as a separate trial.

Structure, relief and patterned optical effect

Fine structure is produced by curing the surface before the bulk, so that the film wrinkles as the full cure shrinks it. Lamp type, cure sequence, power, distance and line speed are recorded as part of the effect specification, because a change in cure changes the texture even when the applied weight is unchanged. Heavy relief is screen applied and needs a cure with enough depth of penetration to harden the full film, not only the surface. For the patterned optical effect grade, the accuracy of the image carrier governs the result, so plate, screen and pattern pitch are specified together with the coating.

Downstream and handling

Effect coatings change how a sheet behaves after the press. Check slip and stacking on relief and glitter work, check folding and creasing on heavy films, and confirm that glue lines are either kept free of coating or are compatible with the adhesive in use. The matt, structure and leafing metallic grades cure to a low energy surface, so where the pack is foil blocked, hot stamped, laminated or overprinted later, the full sequence is tested rather than assumed. A press trial on the customer press and the production substrate is required before any effect is committed to a production specification.

Arctic specifies an Arcvista grade against the job, not against the effect name alone. The following is what we need to know.

• What is the effect meant to replace, if anything: cold foil, hot foil, metallised board, an embossing die, or a separate decoration pass?
• What is the exact substrate, including coating type, board grade, absorbency, recycled content and any lamination or pre-coat? Name the production stock, not the proofing stock.
• Which units are available and in what order: how many ink stations, how many coaters, is there an in-line screen unit, and what anilox line counts and volumes are on hand?
• What is the cure on the line: UV lamp type, installed power, number of lamps, and whether an interdeck, short wave or two-stage cure is available?
• For drip-off, what ink set, fount solution and powder settings will run the job, and is the matt pattern a small highlight or a large field?
• What relief height, particle size or lustre level is the target, and is there a physical sample or an agreed reference to work to?
• What happens to the sheet afterwards: die cutting, creasing, folding, gluing, foil blocking, lamination or overprinting, and where do the glue lines fall?
• What are the run length, press speed and coverage, so the commercial case against foil or metallised board can be calculated for this job?
• What is the end use of the pack, and which regulations must the finished pack satisfy? A compliance dossier or declaration is issued on request with the Technical Data Sheet.
• What test methods and acceptance limits will be used at incoming inspection, so the Certificate of Analysis is issued against the right properties?

The Technical Data Sheet, Safety Data Sheet and regulatory declaration for any grade in this range are issued by our laboratory against the substrate and process you are running. Tell us the job and we will specify against it.