The world of printing is vast and profound, but its core technologies ultimately fall into four main categories. Whether it's books, packaging, or exquisite art albums, all rely on these fundamental printing processes. Today, let's systematically understand these four traditional printing classifications and their modern developments.
Based on the plate surface structure, traditional printing is mainly divided into the following four types:
1. Planographic Printing (Offset Printing)
Currently, offset printing is commonly referred to as planographic printing. The image and non-image areas of the plate lie on the same plane. Using the principle of oil-water separation, the image is ultimately transferred to the substrate surface.
Plate Characteristics: The image and non-image areas are almost on the same plane.
Common Types: PS plate, deep-etch plate, multi-metal plate, etc.
Printing Principle: Utilizes the natural repulsion between oil and water. The image area is oleophilic (attracts ink), while the non-image area is hydrophilic (repels ink).
Key Point: Precise control of water-ink balance is required. To keep the non-image area clean, the amount of water should be as minimal as possible.
Main Features:
Indirect Printing: Ink is first transferred to a rubber blanket, then to paper. The blanket's elasticity produces a sharp impression.
Halftone Color Reproduction: Original images are separated into four color plates (CMYK) with different screen angles and densities. Colors and tones are reproduced through overlapping and juxtaposition of halftone dots.
High Production Efficiency: Simple platemaking, fast printing speed, accurate registration.
Good Quality, Wide Range: Fine details, rich tones, excellent color fidelity, suitable for various substrates.
Main Applications: Books, magazines, art albums, posters, commercial promotional materials – the vast majority of paper-based printed matter.
2. Relief Printing (Letterpress Printing)
The image area is raised above the non-image area. Ink is applied to the image area, and the image is transferred to the substrate under pressure. This is the oldest printing method, similar in principle to seals and woodblock prints.
Printing Principle: All image areas on the plate are raised to the same height, while non-image areas are recessed. During printing, the raised areas receive ink and are pressed directly onto the substrate.
Main Features:
Sharp Impressions, Rich Ink: Even on rough paper, results are good.
Various Plate Materials: Traditional wood blocks, lead movable type, as well as copper plates, zinc plates, etc.
Simple Equipment Structure: Such as platen presses, easy to operate.
Suitable for Special Materials: Ideal for small areas, short runs, very thick materials, rough or uneven paper, and plastics.
Disadvantages & Challenges:
Complex platemaking, difficult quality control – not suitable for color printing with rich tones and large formats.
Long platemaking cycle, slow printing speed, low efficiency.
Traditional lead and copper-zinc plate processes have environmental pollution issues.
Movable type layout occupies large space and is labor-intensive.
Main Applications: Previously widely used for newspapers and books (especially monochrome text books). Its mainstream position has now been replaced by planographic printing, but it still exists in some special fields and in the form of flexography.
3. Intaglio Printing (Gravure Printing)
Opposite to relief printing, the image areas are recessed below the plate surface, while non-image areas remain at the original level. Ink fills the recessed cells, and under high pressure, the ink is transferred to the substrate surface.
Main Features:
Thick Ink Layer, Rich Tones: The only conventional printing method that uses varying ink layer thickness to represent tonal gradations. Images have rich layers and strong shadow detail.
Wide Substrate Range: Various solvents and resin types allow printing on non-paper materials such as plastic films and cellophane.
High Platemaking Difficulty, High Cost: Long platemaking cycle and complex process, but this also provides some anti-counterfeiting capability.
Main Applications: Security printing (banknotes, postage stamps), high-end art albums, cigarette packaging, flexible plastic packaging, etc.
4. Porous Printing (Screen Printing / Stencil Printing)
The image areas consist of holes (mesh openings). Under the pressure of a squeegee, ink passes through the mesh openings onto the substrate. This is a typical example of "perforated stencil printing."
Printing Principle: The stencil is placed over the substrate. Ink is applied with a squeegee, and the ink passes through the
mesh openings in the image area, forming the print.
Main Features:
Extremely Thick Ink Layer: Approximately 5–10 times that of planographic printing. The print has a slight raised texture, strong three-dimensionality, and rich color.
Prints on Almost Anything: Can print on objects of any shape or material, with flexible sizes.
High Ink Adaptability: Can use virtually any type of printing ink.
Simple Equipment: Low requirements for printing conditions.
Limitations: Lower plate durability, slow printing speed, average color fidelity.
Main Applications: Textile printing, ceramic and glass decals, circuit board printing, billboards, product labels, crafts, etc.
Important Modern Developments of Traditional Printing
The above four methods – planographic, relief, intaglio, and porous – form the foundation of printing technology. Technological advances have also led to important branches:
5. Flexographic Printing (Branch of Relief Printing)
Originally called "aniline printing," using soft rubber plates. Modern flexography uses flexible photopolymer plates, with inks that are mostly environmentally friendly water-based or UV inks. Combining the advantages of relief, planographic, and intaglio printing, flexography offers high printing speed, a wide range of substrates (especially suitable for various packaging materials), and environmental friendliness.
Main Applications: Food packaging, cardboard boxes, plastic bags, self-adhesive labels, etc.
6. Specialty Printing
Based on different substrates and special effects, many specialty printing technologies have emerged, such as:
Surface Finishing: Hot foil stamping, embossing/die-cutting, varnishing, laminating.
Special Substrates: Metal printing, glass printing.
Special Ink Effects: Foam printing, fragrance printing, fluorescent printing.
Digital & Emerging Technologies: Self-adhesive label printing, 3D printing, inkjet printing, holographic printing, etc.
Summary
From a core principle perspective, all printing can be classified into the four systems of planographic, relief, intaglio, and porous. In practical production and application, we need to flexibly choose among offset, gravure, flexo, screen, or various specialty printing processes based on factors such as substrate material, product quality requirements, print quantity, cost, and special effects. Technological integration and innovation continue, but understanding these fundamentals is the first step into the colorful world of printing.
Post time: Apr-23-2026