What is the difference between gravure and rotogravure?

The Foundation: Gravure Printing

At its core, gravure printing is an intaglio printing process, meaning the image is etched or engraved below the surface of the printing plate. Unlike letterpress (where the image is raised) or lithography (where the image is on the same plane and relies on oil and water repulsion), gravure relies on tiny, recessed cells or wells to hold the ink.

Here's how it generally works:

1. Engraving: The image to be printed is precisely engraved onto a printing cylinder, creating microscopic cells of varying depths and sizes. These cells will ultimately hold the ink. The depth and size of these cells directly correlate to the intensity of the color – deeper and wider cells transfer more ink, resulting in darker tones.

2. Inking: The entire cylinder is flooded with a fast-drying, low-viscosity ink.

3. Wiping: A doctor blade then scrapes away the excess ink from the non-image areas, leaving ink only in the recessed cells.

4. Transfer: The substrate (such as paper, film, or foil) is pressed against the engraved cylinder, and the ink is drawn out of the cells onto the material, usually aided by pressure and electrostatic assistance.

5. Drying: Due to the low viscosity and rapid evaporation of gravure inks, the printed material dries almost instantly.

Gravure printing is renowned for its exceptional print quality, particularly in reproducing continuous tones and vibrant colors. It's often chosen for applications where image fidelity and consistency are paramount.

The Evolution: Rotogravure Printing

Rotogravure is, quite simply, gravure printing on a rotary press. The "roto" prefix signifies the use of a continuous, rotating cylinder, making it ideal for high-speed, long-run production. This is the dominant form of gravure printing used in industrial and commercial applications today.

Key characteristics and advantages of rotogravure include:

• High Speed: The continuous rotary motion allows for incredibly fast production speeds, making it highly efficient for large print runs.

• Durability of Plates: The engraved cylinders (also known as gravure cylinders, printing rollers, or image carriers) are typically made of steel and electroplated with copper and then chrome, making them extremely durable and capable of producing millions of impressions without significant wear. This durability contributes to excellent consistency over long runs.

• Versatile Substrates: Rotogravure is highly adaptable and can print on a wide range of materials, including thin films (for packaging), paper, cardboard, and even metallic foils.

• Superior Image Quality: It excels at producing smooth gradations, sharp details, and rich, consistent colors, which is why it's a preferred method for high-end magazines, catalogs, flexible packaging, and decorative laminates.

• Cost-Effectiveness for Long Runs: While the initial cost of cylinder engraving can be high, the per-unit cost becomes very low on extensive print jobs due to the speed and durability of the gravure machine or rotogravure press.

The Synonyms and the Summary

When discussing a gravure machine, you might encounter several equivalent terms that all refer to the same type of printing apparatus, especially in the context of rotogravure:

• Rotogravure Press

• Gravure Press

• Intaglio Printing Press (a broader term, but applicable)

• Cylinder Press (emphasizing the rotary cylinder)

• Printing Machine (general term, but context usually clarifies)

In summary, the difference is one of scope and application:

• Gravure is the overarching printing method based on intaglio engraving.

• Rotogravure is the specific and widely adopted implementation of gravure printing using rotary presses, primarily for high-speed, high-volume commercial and industrial production.