Printing Techniques

Approximate period: 1890–1905
(With later developments, it continued to be used throughout the 20th century.)

Lithography is one of the most foundational and defining printing techniques in postcard history. It is often summarized with a single phrase: oil and water repel each other. But that principle becomes truly clear only when you understand how the surface is prepared and how the ink is guided.

Lithography is a planographic process: the printing surface is not carved, engraved, or raised.

Early lithography used smooth limestone; later, metal plates became common. In either case, the surface contains microscopic pores, and that fine structure is at the heart of how lithography works.

What does the “oil and water” principle actually mean?

Lithographic printing ink is oil-based. Water functions as an active control layer that determines where ink can and cannot adhere.

The process works like this:

• The image is drawn using a greasy drawing material.
• Image areas become ink-loving and water-repellent.
• Non-image areas become water-loving.
• The surface is dampened before printing.
• Oil-based ink adheres only to the image.

When paper is pressed onto the surface, only the inked image transfers, and the printed picture is formed.

Because of this principle, lithography typically:

• produces a flat print,
• does not create an embossed or raised feel,
• is well suited to fine linework and detailed drawing-like textures.

Greasy drawing materials used in lithography

Lithographic images are not drawn with ordinary pencils or casual paints. The materials must contain grease so the surface can “remember” the image as an ink-receptive area. The most common greasy drawing materials include:

1) Lithographic crayon
The most classic and widely used tool. It typically contains wax, soap, oils, and carbon pigments. Different hardness grades allow control of tone and line: softer crayons produce darker, richer marks, while harder crayons create finer, more controlled lines.

2) Greasy ink / tusche
Used for a freer, more painterly effect. Tusche is a fluid, often near-black substance applied with a brush or reed pen. It produces soft transitions and wash-like areas.

3) Grease-chalk-like mixtures
In some cases, artists prepared custom mixtures and adjusted the grease content to control tone and texture. This is more common in fine art prints than in mass postcard production.

How the printing cycle shapes lithography

Because there is no carved relief—everything exists on one plane—the stone or plate is repeatedly dampened, inked, and placed under mechanical pressure.

What happens as more impressions are printed?

As the number of impressions increases, the surface gradually wears: edges can soften, fine lines may lose sharpness, and overall contrast can decrease.

What to look for on a postcard

• Flat ink layer: no raised impression typical of letterpress.
• Drawn character: outlines and shading feel illustrated.
• Hatching and line-based shading are common.
• Layered color work may show slight registration shifts.

Why it matters for collectors

Lithography forms a backbone of early postcard production. Early impressions are often cleaner and more contrast-rich, while later impressions may show softening and background toning.

Approximate period: c. 1890–1910

Chromolithography is the multi-color extension of lithography. Its fundamental principles are identical, but what makes chromolithography significant is the expansion of those principles through multiple colors and repeated printing passes.

This technique transformed postcards from simple reproduced images into vivid, visually engaging objects designed to attract and to be kept.

How does it differ from lithography?

While basic lithography can rely on a single printing surface, chromolithography requires a separate stone or plate for each color. The image must be prepared individually for every color layer.

As a result, a single chromolithographic postcard may involve many successive printings, depending on the number of colors used.

Why do the colors look so rich?

In chromolithography, colors are not mechanically mixed. Instead, transparent or semi-transparent inks are layered on top of one another to build tones and intermediate hues.

The result is:

• a strong sense of depth,
• warm and saturated colors,
• soft, painterly transitions.

For this reason, chromolithographic postcards often feel closer to a painted surface than to a photographic reproduction.

The cost of complexity: sensitivity

This layered structure also makes chromolithography inherently delicate. Common characteristics include:

• Slight color misregistration: colors not aligning perfectly,
• Imbalanced tones: some colors appearing heavier,
• Loss of layer clarity: surfaces looking visually filled in.

These characteristics are not always defects. For collectors, they can provide valuable clues about production order, print runs, and impression quality.

What to look for on a postcard

• Strong, saturated colors
• Visible layered color construction
• Slight color shifts along edges
• No regular halftone dot pattern
• Painterly or illustrated appearance

Under magnification, overlapping color boundaries become visible instead of uniform dot screens.

Relationship to lithography

Chromolithography does not replace lithography; it represents its natural expansion. The underlying method remains the same, but the visual ambition increases through the multiplication of color layers.

Why it matters for collectors

Chromolithography defines the visual identity of many classic postcards. Early impressions are often clearer and more balanced, while later impressions may show heavier colors or alignment issues.

Approximate period: late 19th century – early 20th century
(Widely used before and alongside lithography in early postcard production.)

Letterpress is a relief printing technique. Unlike lithography, which operates on a flat surface through chemical principles, letterpress relies on a physical fact: the image is raised above its surroundings and pressed directly into the paper.

This structural difference gives letterpress postcards a distinct visual character and an unmistakable tactile presence.

How the raised image is created

• Carving: Non-image areas are cut away, leaving image areas raised.
• Metal casting: Raised plates cast from a master form.
• Assembled type and blocks: Individual letters and decorative elements set to uniform height.

Regardless of the method, the result is the same: only the raised areas receive ink and make contact with the paper.

The tactile clue: impression

• Printed areas may feel slightly raised or indented.
• Under angled light, the impression may become visible.
• On thinner paper, the effect may appear on the reverse side.

Visual characteristics

• Bold, clearly defined lines
• Strong contrast
• Limited tonal variation

Because tone cannot be built gradually as in lithography, letterpress images often appear more graphic and assertive.

Color and its limitations

Each color requires a separate printing pass. Smooth gradients are difficult, and large solid color areas are more common than subtle transitions.

Wear, pressure, and variation

• Excessive pressure can cause ink spread at edges.
• Repeated printings wear down raised surfaces.
• Uneven pressure may create inconsistent ink density.

Why it matters for collectors

Letterpress postcards play an important role in early postcard history. Clean impressions with sharp edges are generally preferred, while heavy ink spread or damaged paper reduces appeal.

Approximate period: c. 1890–1915
(Used on a limited scale in later years.)

Collotype is widely regarded as one of the most photographic printing techniques used in postcard production. Unlike lithography or chromolithography, which retain a drawn or painterly character, collotype images often appear almost indistinguishable from true photographic prints.

What makes collotype different?

The defining feature of collotype is that images are produced without drawn lines and without a regular halftone screen. Instead of dots or line structures, the image is formed through continuous tonal variation.

Light and shadow transitions appear smooth and uninterrupted, clearly separating collotype from other contemporary printing methods.

Printing surface and principle

In collotype, a glass or metal plate is coated with a light-sensitive gelatin layer. A photographic negative is placed over the plate and exposed to light. Areas receiving more light harden more strongly than darker areas.

During printing, hardened areas accept less ink, while softer areas accept more. These microscopic differences in ink absorption allow the image to be built tone by tone.

Why collotype looks so photographic

Because no halftone screen is used and no drawn structure is present, tonal transitions remain smooth and natural. Fine detail can be reproduced without visible dot patterns.

Limitations of the process

Collotype is technically delicate. The gelatin surface is sensitive to temperature and humidity and wears down relatively quickly during long print runs.

For this reason, print runs are usually limited and large-scale mass production is impractical.

What to look for on a postcard

• Photographic appearance with soft tonal transitions
• No visible halftone dot pattern
• No drawn outlines or hatching
• Fine, irregular surface texture under magnification

Why it matters for collectors

Because of its technical difficulty and limited print runs, collotype holds a special place in postcard collecting. Well-preserved examples with balanced contrast and clean tonal transitions are especially valued.

Approximate period: c. 1900–1930s
(Earlier or later examples may appear depending on region and local practice.)

Real Photo Postcards are, as the name suggests, based on true photographic prints rather than printing processes. They are not produced by a printing press but created directly on photographic paper using darkroom techniques.

This fundamental difference places RPPCs outside all traditional printing methods and gives them a unique position in postcard history.

How RPPCs differ from printed postcards

• Produced through a chemical photographic process
• Use light-sensitive photographic paper
• Contain no ink and show no printing pressure

An RPPC is therefore not a reproduction of a photograph — it is the photograph.

How RPPCs are produced

• A negative (glass plate or film) is prepared.
• The image is exposed directly onto photographic paper.
• The paper is developed, fixed, washed, and dried.

The finished postcard never passes through a printing press and contains no ink layer.

Photographic paper and surface characteristics

• Glossy finish
• Semi-matte finish
• Matte photographic paper

The surface reflects light differently from printed postcards and often feels smoother and more glass-like.

Tone, detail, and realism

• Continuous tonal range
• No raster dots or drawn lines
• Detail defined by the camera and negative

Common confusion with collotype

• Collotype is a printing process; RPPC is a photograph.
• Collotype may show gelatin texture; RPPC does not.
• RPPC surfaces show the chemical sheen of photographic paper.

Why it matters for collectors

RPPCs often document everyday life, local events, and personal histories. Because many were produced in small quantities by local photographers, they can be historically unique and highly desirable.

Approximate period: c. 1890–1940
(Particularly common in high-quality illustrated postcards and art reproductions.)

Photogravure is an intaglio printing process, meaning the image is created by ink held in recessed areas below the surface of a metal plate. Unlike lithography or letterpress, the image is not flat or raised, but engraved into the plate.

How the process works

A photographic image is transferred onto a copper plate coated with a light-sensitive gelatin tissue. Through exposure and chemical etching, tiny recessed cells of varying depth are created.

During printing, ink is forced into these recessed cells. The surface of the plate is wiped clean, leaving ink only in the engraved areas. Under high pressure, the paper draws ink out of the recesses.

Why tonal depth is so rich

Because the depth of each recessed cell controls how much ink it holds, photogravure can produce exceptionally smooth tonal transitions and deep shadows. Dark areas contain deeper cells; lighter areas contain shallower ones.

The result is a print with a subtle, often slightly textured surface and a remarkable sense of depth.

How to identify photogravure

• Fine cross-line or grid-like screen under magnification
• No raised ink or relief impression
• Rich blacks and smooth shadow transitions
• Slight plate impression may be visible at edges

Under magnification, the image appears structured by tiny engraved cells rather than by surface dots.

Relationship to other techniques

Photogravure can be confused with high-quality halftone printing, but halftone dots sit on the surface, while photogravure ink lies below the plate surface in engraved recesses.

Compared to collotype, photogravure shows a regular engraved structure rather than an irregular gelatin texture.

Why it matters for collectors

Photogravure was widely used for art reproductions and high-end illustrated postcards. Its tonal richness and refined appearance often signal a quality production.

Approximate period: c. 1920–1940
(Widely used for illustrated postcards, magazines, and high-volume image reproduction.)

Rotogravure is a form of intaglio printing, closely related to photogravure. The key difference lies in its industrial adaptation: instead of flat plates, rotogravure uses engraved cylinders designed for high-speed rotary presses.

How the process works

The image is engraved into a metal cylinder, creating thousands of tiny recessed cells. These cells vary in size or depth to control tonal values.

During printing, the cylinder rotates through ink. Excess ink is wiped off the surface, leaving ink only inside the recessed cells. Paper passes under pressure and draws ink from these cells.

Visual character

Rotogravure produces smooth tonal transitions and rich shadow areas. Compared to photogravure, the structure is typically more regular and mechanically consistent.

Under magnification, a fine grid of engraved cells becomes visible. Unlike halftone offset dots, these cells are recessed below the surface and often appear slightly square or honeycomb-like.

How to distinguish from photogravure

• Rotogravure uses rotary cylinders; photogravure traditionally uses flat plates.
• Rotogravure cell patterns are highly regular and industrial.
• Photogravure often shows slightly more artisanal variation.

Surface characteristics

Like other intaglio processes, rotogravure leaves no raised ink. In some cases, a very subtle plate impression may be visible at the edges, but the overall feel is smooth.

Why it matters for collectors

Rotogravure represents the industrial phase of high-quality image reproduction between photogravure and offset printing. Recognizing it helps collectors correctly date postcards from the interwar period and avoid confusion with earlier photogravure techniques.

Approximate period: 1930+
(Becoming dominant in commercial postcard production from the mid-20th century onward.)

Offset lithography is a modern evolution of traditional lithography. It remains a planographic process, based on the same oil-and-water principle, but introduces an intermediate transfer stage.

How offset differs from classical lithography

In classical lithography, ink transfers directly from the stone or plate to the paper. In offset printing, the image is first transferred from a metal plate to a rubber blanket cylinder, and only then from the blanket to the paper.

This indirect transfer improves durability of the plate and allows for high-speed, large-volume production.

Halftone structure and color printing

Offset printing typically relies on halftone screens to reproduce tonal variation. Continuous-tone images are broken into tiny dots arranged in regular patterns.

In color printing, four-color CMYK separation is common. Under magnification, overlapping dot patterns may form a characteristic rosette structure.

Surface characteristics

Because offset is not a relief or intaglio process, it leaves no physical impression in the paper. The surface feels smooth and mechanically even.

Ink layers are generally thin and evenly distributed, contributing to a clean and standardized appearance.

What to look for on a postcard

• Clearly visible halftone dots under magnification
• Regular grid or rosette pattern
• No plate mark or embossed impression
• Uniform and mass-produced look

Why it matters for collectors

Offset lithography marks the transition to modern industrial postcard production. While technically efficient, it often lacks the tactile and artisanal qualities of earlier techniques.

Coming soon: Visual examples of postcards combining multiple printing techniques — chromolithography + halftone, collotype + hand-tinting, letterpress + chromolithography, and more.

Each example will include magnified details highlighting where one technique ends and another begins.