Have you ever ordered the same spot colour for two different jobs and received two visually different results, even though the recipe was identical? It is not a manufacturing error. It is the physics of how light interacts with the surface you print on — coated sheet, uncoated paper, packaging board or film.

Ink does not have a single “true” colour. It has a fixed pigment recipe which, once applied to a substrate, behaves according to how much of that substrate absorbs light and how much it reflects back to the eye. Coated paper, uncoated paper, board and metallised film are not interchangeable variants of the “same white substrate” — they are materials with fundamentally different optical properties, which directly influence the result on an offset or flexo press.

At Printman, this reality underpins our special ink mixing service. We have our own laboratory, equipped with Techkon spectrophotometers, precisely because the recipe on paper is not enough — the final colour has to be verified on the real material on which the printing company is going to produce the run.

 

 

1. Our own Flint ink mixing laboratory

One of the most frequent challenges for a production manager in an offset printing company is the reproducibility of a spot colour across successive runs. The client comes with a physical sample or a colour reference code, and the printing company has to deliver an identical shade, on the real printing substrate, whether the ink batch is used today or in three months' time. Without a professional mixing system, this requirement is practically impossible to meet accurately.

1.1 The brand of mixed ink: Flint Group

Printman's custom mixing service uses exclusively Flint Group ink bases — one of the largest manufacturers of printing inks in Europe. Reference codes (PMS, HKS or other SPOT standards) are used only as a language for communicating the required shade, not as the brand of the ink itself. 

For mixing spot colours on sheetfed offset presses, the standard base is the Novavit BCS series — a vegetable oil-based ink whose 12 fundamental colours (plus opaque white, transparent white and black) are specially optimised to be combined into any required shade, with the degree of resistance the job calls for.

1.2 How the mixing process works at Printman

The in-house Printman laboratory is equipped with state-of-the-art Techkon spectrophotometers and professional colour management software. The mixing process follows rigorous technical steps, designed specifically to eliminate the variables that can affect the final result on press:

• Identifying the required colour code — PMS, HKS, another SPOT standard, or a physical sample sent by the printing company
• Adapting the recipe to the real printing substrate — if you send us the material you will print on (coated paper, uncoated, board, film), we formulate the colour specifically for that substrate
• Mixing with Flint Group bases — Novavit BCS for commercial sheetfed printing, Novaboard for board and difficult absorbent substrates, Novasens with ISEGA certification for food packaging
• Instrumental verification with the Techkon spectrophotometer — we measure the ΔE shade differences and keep them to an absolute minimum
• Automatic dosing and digital archiving of the recipe — we can reproduce any previous colour, at any time, for any future reprint order

 

 

1.3 Why the recipe is not enough without verification on the substrate

A mixing recipe that is mathematically correct can still produce a visually wrong result if it is not verified on the client's real material. The thickness of the layer of ink applied directly influences the colour density — the same recipe, laid down in a thicker or thinner film on the offset press, produces visibly different shades. For this reason, the Printman laboratory does not stop at calculating the recipe: every batch is physically verified, on the substrate declared by the printing company, before delivery.

 

2. The Printman calendar: 12 months, a single ink

To demonstrate this principle visually and concretely, we produced our own Printman calendar with a simple theme: 12 months, a single ink. Every month of the calendar uses exactly the same Flint ink — the same recipe, the same application thickness, the same printing parameters — but printed on a different substrate.

The result is a direct demonstration of a phenomenon our technical team explains daily to clients in offset and flexo printing companies: every type of substrate absorbs and reflects colour differently, showing how a single ink can have twelve different appearances. Placed side by side on the page, each substrate develops the same ink in ways the eye distinguishes immediately — from warmer, more saturated shades on coated substrates, to more matt and muted tones on uncoated papers or on boards with high absorbency.

2.1 What the calendar actually shows

The calendar is not a decorative item — it is a technical educational tool for Printman's clients and partners in the printing industry. Each page visually illustrates the difference in optical behaviour of the same ink on a different type of material:

• Coated paper — the ink film stays more on the surface, which produces more vivid colours, higher contrast and stronger saturation
• Uncoated paper — the ink penetrates deeper into the fibrous structure of the paper, reducing colour density and blurring the purity of the shade
• Packaging board — the whiteness and the level of absorbency differ significantly from paper, changing the overall perception of the colour
• Non-absorbent substrates (film) — the ink stays entirely on the surface, with no absorption, resulting in completely different saturation and gloss

 

The difference is not a defect of the ink — it is the physical property of each material. The whiteness of the substrate, the surface texture and the level of absorbency together form a variable just as important as the colour recipe itself.

 

2.2 Why we created this calendar for offset and flexo printing companies

Many printing clients naturally assume that once a spot colour is “fixed” by a reference code, the result will be identical regardless of the material. The Printman calendar visually dismantles that assumption, in a format that any offset, flexo or packaging production client can see and physically touch, month after month, over a whole year.

The purpose is not only to demonstrate. It is also preventive: understanding this difference before placing a large run order avoids unpleasant surprises at final delivery — surprises that, on industrial runs of tens of thousands of sheets or linear metres of reel, cost time, material and the end client's trust.

 

3. Why the substrate matters as much as the ink recipe

In the printing industry, attention often focuses exclusively on the ink: pigmentation, resistance, drying speed. The substrate frequently remains the ignored variable — even though it influences the final result as much as the chemical formula of the ink, in both offset and flexo.

3.1 The factors that determine how the eye “reads” a colour

The perception of a printed colour is influenced simultaneously by several critical factors, not just by the ink recipe:

• The thickness of the ink film applied to the substrate — determined by cylinder pressure in offset or by the volume of the anilox roll in flexo
• The type of lighting under which the work is viewed (D50, D65, LED, natural light)
• The optical properties of the substrate — whiteness, texture, level of absorbency
• The neighbouring colours on the same page, which can influence visual perception through contrast

The same ink recipe, applied to coated paper versus uncoated paper, can produce a difference in perception similar to that between two completely different colours. The phenomenon is not a printing error — it is the normal physical behaviour of the materials involved.

3.2 Metamerism — the same code, a different result under different light

Besides the differences caused by the substrate, there is also the phenomenon of metamerism: the same colour recipe can produce perceived visual differences depending on the light source. A job can look correct in the printing company's control room, but different in a shop or in natural daylight. The combination of substrate influence and metamerism explains why visual verification “by eye” is not sufficient for the consistent reproduction of a colour — and why instrumental measurement, on the real substrate, remains the only reliable method, especially on industrial runs where consistency across hundreds of thousands of copies is critical.

3.3 How to prevent colour surprises before the big run

The recommendation of the Printman technical team for any mixed ink order is simple: send us the real substrate you will print on. We formulate and verify the colour directly on that material, not on a generic test substrate. This step eliminates the risk that a colour approved on a laboratory test looks different on the final run, delivered on a different type of paper, board or film than the one used for the sample — a risk that is particularly costly on the long runs typical of offset printing companies and flexo packaging manufacturers.

4. Ink mixing for offset versus industrial flexo

Although the physical principle — the influence of the substrate on colour perception — is identical, the technical mixing process differs according to the printing technology the ink is intended for.

4.1 Mixing for offset printhouses

For sheetfed offset printing companies, the Printman mixing service uses Flint Novavit BCS bases, Novaboard (for board and difficult absorbent substrates) and Novasens (for food packaging, with ISEGA certification). The recipes are optimised for the ink-water balance specific to the offset process and verified on press to confirm colour stability throughout the entire run.

4.2 The particularities of inks for narrow-web flexo

For industrial flexo printing companies, especially those specialising in narrow-web labels and packaging, the Printman portfolio covers UV and LED UV inks curing by polymerisation, not by oxidation as in conventional offset. These inks require different control of the film thickness — determined by the volume of the anilox roll — and are formulated for a range of 12 base shades, optimised to allow any required colour to be mixed directly on press or pre-mixed to order.

Whether your printing company works on sheetfed offset or on narrow-web flexo, the principle remains the same: the final colour depends on the interaction between the ink recipe and the real substrate, and spectrophotometric verification on the production material is the only way to eliminate surprises on the run.

 

5. Frequently asked questions about ink mixing

Why does the same spot colour look different on coated paper compared with uncoated paper?

The difference comes from the optical properties of each substrate. Coated paper has a treated surface that reduces ink absorption, leaving the ink film more on the surface — the result being more vivid colours and higher contrast. Uncoated paper absorbs the ink deeper into its fibrous structure, which reduces the density and saturation of the perceived colour. The Flint ink remains chemically identical — what differs is only the way the substrate “presents” it to the eye.

Is the ink mixed by Printman Pantone or Flint?

The physical ink used is always Flint Group — Novavit, Novaboard or Novasens bases, depending on the application. Codes such as PMS or HKS are used only as a reference standard to communicate the required shade; they do not represent the brand of the ink. Whatever code is used to describe the colour, the formula and the manufacture remain Flint.

Can I send a physical colour sample instead of a reference code?

Yes. The Printman laboratory accepts physical samples and formulates the Flint ink by spectrophotometric measurement with Techkon equipment, adapting the recipe to the printing company's real printing substrate. This method is often more accurate than a generic reference code, especially when the final production material differs from the standard used to create the colour guide.

What difference does it make if I also send the substrate I will print on?

An essential difference. The same ink recipe produces different visual results depending on the whiteness, texture and level of absorbency of the material. If you send the real substrate — paper, board or film — we formulate and verify the colour exactly on that material, eliminating the risk that a colour approved on a generic sample looks different on the final run, especially in high-volume industrial production.

Does Printman's mixing also cover inks for narrow-web flexo, not just offset?

Yes. For industrial flexo printing companies, the Printman portfolio covers UV and LED UV inks curing by polymerisation, formulated to allow any required shade to be mixed. The technical process differs from offset — particularly regarding the control of film thickness through the anilox roll — but the principle of verification on the real substrate remains identical.

How quickly do I receive the mixed ink I order?

Thanks to the automatic dosing system in our own laboratory, we deliver mixed Flint inks the same day in most cases. Orders start from 1 kg, with no artificial minimum thresholds, which allows both one-off orders for small jobs and industrial volume production for large printing companies.

Can I reproduce exactly a colour I ordered six months ago, for a reprint?

Yes. Every recipe mixed in the Printman laboratory is archived digitally, together with the substrate it was calibrated for. On a future reprint order, we can reproduce the same colour accurately, without starting the formulation process from scratch — essential for printing companies working on recurring orders for the same end client.

 

6. Conclusion — the right colour, on your real material

Ink mixing is not a simple mathematical operation of combining pigments to a fixed recipe. It is a process that has to take account of the real material the job will be printed on — because, as the Printman calendar “12 months, a single ink” clearly demonstrates, the same Flint ink can have twelve visually different appearances, depending exclusively on the substrate.

At Printman, we know that the material matters as much as the ink. That is why we have our own laboratory, equipped with Techkon spectrophotometers, able to formulate and verify every Flint colour directly on the printing company's real substrate — whether you work on sheetfed offset or on narrow-web flexo for packaging and labels.

If you need a reproducible spot colour, whatever the substrate, or you want to avoid colour surprises on an industrial run, our technical team can help you achieve exactly the result you expect.