What is ink mileage? It is the area a given weight of ink will cover at a stated film thickness, usually expressed as square metres per kilogram or as grams per thousand sheets. Ink is a small line in a packaging quotation, but it is the line that moves when a design changes from a light tint to a full solid, and it is worth understanding before a redesign is approved on aesthetics alone.
How is consumption estimated? The starting point is the coverage of each colour as a percentage of the sheet area, taken from the artwork. That coverage is multiplied by the sheet area and by the ink film weight the process lays down, then adjusted for the number of impressions and the waste allowance. A four-colour job with heavy solids uses many times the ink of a one-colour job with small type, and the estimate should show that difference rather than average it away.
Why does coverage dominate? A 5 percent tint and a 95 percent solid differ by a factor of nineteen in ink volume, before any allowance for film thickness. Large flat backgrounds, full-bleed photographs and heavy dark panels are the expensive areas, while text and line work cost little. A design that replaces a solid background with a tint, or uses the board colour as part of the design on kraft stock, can cut ink consumption substantially without changing the print process.
Where do estimates go wrong? Film thickness is the usual culprit. Ink density targets, press conditions and the substrate all change how much ink is laid down, and a figure taken from a coated sheet understates what an absorbent uncoated board will drink. Waste is the second: make-ready sheets, colour approvals and running spoilage all consume ink, and a job with a difficult colour match may use a noticeable share of its ink before the first saleable sheet.
How much of the price is ink? On a folding carton, ink is typically a modest share of the unit price, well below board and often below labour and finishing. On labels and on small cartons with heavy coverage, the share rises because the printed area is a larger fraction of the material. On corrugated printed direct, ink is cheap per square metre but the coverage is usually low, so the line stays small either way.
Can a buyer reduce it without hurting the design? Several approaches work. Reducing a solid to a tint where the brand allows, using the substrate colour as a design element on kraft or uncoated stock, consolidating colours across SKUs so one make-ready serves several products, an effect described in sheet layout and nesting, and avoiding a white flood coat under a light design when the board is already white. Each change trades a little design freedom for a measurable saving, and the trade is easier to make when the numbers are visible.
What should a buyer ask? Ink consumption per thousand units at the quoted coverage, whether the figure assumes a waste allowance and how much, and whether ink is priced inside the unit rate or billed separately on a price-per-kilo basis. A supplier who can show the assumption behind the ink line is also a supplier who can show what a design change would do to the price, which is more useful than a discount on the total.
Chengtop quotes ink inside the unit price for printed cartons and labels and can show the coverage assumption behind the number at its Wuhan plant. Send the artwork and the quantity, and we will set out what a change of coverage would do to the price.
