Contract colour: digital mock-up versus Heidelberg production sheet

A mock-up is not a press sheet

A screen JPEG, a PDF on a laptop, and a 3D gift-box render are sales tools. They are not a Heidelberg production sheet. Lighting, RGB, and holographic film will move. Write which proof is contractual: digital, wet proof, or press sheet.

We print wrap and carton sheets in the same Longgang plant after Kodak CTP. Colour you can hold is ink on paper from that path — not a filtered mock-up of gold foil.

If the buyer signs only a screen PDF, say so on the RFQ. We will still print a sheet; we will not treat the PDF as the keep-sheet unless you name it as the contract proof — and we will warn that it will not match foil or holographic wrap.

• State which proof is contractual.
• Spot foil and UV sit outside a CMYK proof.
• Approve wrap sides, not only a front hero.

What we can match

A printed wrap sheet or carton from the same press family is a matchable object. Pantone on coated paper is a start. Uncoated kraft, coloured board, and holographic film will shift; say if that shift is acceptable.

If the brand has a viewing-booth standard, send it. Otherwise we OK on a daylight sheet. Returning last year’s physical wrap is better than a hex code in an email.

What we will not promise in an article

We will not invent Delta-E numbers, a fake spectro log, or a guaranteed match to a phone photo. Those claims belong in a QC protocol you attach — not in marketing copy.

Catalog photos of pink, kraft, or holographic boxes are colour/structure references. They are not a locked ink formula you can reorder by nickname.

Spot versus process

Brand red on a book-style box is often a spot. Process-only CMYK will drift lot to lot, especially on large solids. Write spot versus process on the RFQ, and which panels carry the brand colour.

Heidelberg catalog names (8-open 4/5, XL-75 4/5, CDX102 4/5/6) describe in-house sheetfed capacity. They do not mean every job is six-colour. Extra units are for when the map needs them.

Foil, UV, and film live beside ink

Foil, spot UV, and lamination sit on a finish map. A CMYK digital proof will not show foil bounce or UV gloss. Approve those on a physical dummy or a drawn map plus a sheet, not on the mock-up alone.

Holographic wrap will not match a social-media render. Say if movement is acceptable. Do not treat a GIF of sparkle as a contract.

Who signs which face

Approve all wrap sides that print, including spine, lid inner if printed, and dust flaps if they show. A hero front OK does not cover a mismatch on the base.

Structure sample and colour sample can be two rounds. Fit of a lid is not colour. Do not hold a press sheet hostage to a dieline that is still moving.

First sheet versus the lot

A press OK is a sheet from the run path, not a promise that every carton in a container is that sheet. Lot drift is why spot colours and a named substrate matter. Write how many faces you will hold.

If production follows weeks after the OK, board lots can move. Ask for a keep-sheet against the OK you signed. We will not invent a Delta-E window in this article.

Digital reprints of the mock-up are not a substitute for that keep-sheet. When wrap is holographic or foiled, hold a physical dummy plus the ink sheet, not the GIF.

What fails when the contractual proof is a JPEG

Pick one contractual object before the knife is cut: digital mock-up, wet proof, or Heidelberg production sheet. Spot vs process, finish map, faces, substrate, quantity band, destination.

• Pinch-zoom mock-up as the keep-sheet: lot drift has nothing to hold.
• Foil or holographic wrap approved on a GIF: hold a physical dummy plus the ink sheet.
• Press OK weeks before production with no keep-sheet: board lots move.
• Delta-E invented on this page: write how you will hold faces instead.
• Only the front hero signed: wrap sides still print.