5.2 Planographic and Stencil Printmaking: Lithography, Serigraphy, and Monotype

Planographic and Stencil Printmaking: Lithography, Serigraphy, and Monotype

Unlike relief and intaglio printmaking, which rely on mechanical height differentials (raised plateaus or carved incisions), planographic and stencil printmaking operate along distinct physical and chemical paradigms. Lithography operates entirely on a single, continuous flat plane governed by surface chemistry, serigraphy utilizes open mesh stencils to pass ink through a screen, and monotype explores unique, unrepeatable transfers from smooth surfaces.

1. Planographic Lithography: Chemical Immiscibility and Matrix Physics

Invented in Bavaria by Alois Senefelder in 1796, lithography (literally "stone drawing") is a planographic process in which the image and non-image areas share the exact same physical plane. The entire mechanism depends upon a foundational principle of chemistry: the mutual repulsion of grease and water (immiscibility).

Planographic Surface Chemistry:
[Damp Sponge Water Film]   =====             =====
[Greasy Printing Ink]             =======         
[Limestone Surface]        [Ca-Arab] [Ca-Ole] [Ca-Arab]
                           Hydrophilic Lipophilic Hydrophilic
                           (Attracts   (Attracts  (Attracts
                            Water)      Grease)    Water)

The Matrix: Bavarian Limestone

• Solnhofen Limestone: The historical and pedagogical benchmark for fine art lithography. Quarried in Solnhofen, Bavaria, this fossiliferous limestone is composed of microcrystalline calcium carbonate ($CaCO_3$). Its density and porosity are ideally balanced: it is sufficiently porous to absorb water and greasy fatty acids simultaneously, yet hard enough to withstand high pressure without cracking.
• Alternative Metal Matrices: Grained aluminum and zinc plates are widely used in modern academic and industrial printshops. Aluminum plates are lightweight, space-efficient, and immune to fracturing, though they lack the organic drawing responsiveness and erase/redrawing flexibility of natural limestone.
• Graining and Leveling the Stone: Before drawing, a used stone must be leveled and grained using a heavy cast-iron disc called a levigator or a smaller hand-held graining stone. The printmaker rubs the levigator across the wet stone in continuous figure-eight patterns, feeding abrasives of silicon carbide (carborundum grit) in progressing grades (80, 150, 220, to fine 320/400 grit). This grinding process erases prior greasy images, levels the stone flat, and imparts a sensitive, toothy, velvety grain that holds drawing materials.

Drawing Media: Tusche and Lithographic Crayons

The artist draws directly upon the dry, grained limestone using materials formulated with high concentrations of animal fatty acids, waxes, soaps, and pigment:

• Lithographic Crayons and Pencils: Graded from #1 (extra soft, greasy) to #5 (copal, very hard). Soft crayons produce rich, dense, velvety darks; hard crayons permit crisp, delicate linear shading.
• Liquid Tusche: A greasy liquid suspension containing shellac, tallow, wax, and soap dispersed in water or petroleum solvents. Applied with brushes, dip pens, or airbrushes. When thinned with distilled water, drying tusche separates into delicate reticulated washes ("tusche wash" or alligator-skin texture) that create spontaneous, watercolor-like gradations.

The Chemical Etch: Gum Arabic and Nitric Acid

The most chemically critical phase of lithography is the "etch" (which does not bite deep grooves as in intaglio, but rather modifies surface molecular polarity):

• The Chemistry of Processing: The stone is treated with a measured solution of pure gum arabic (a natural polysaccharide exudate from the acacia tree) acidified with small amounts of dilute nitric acid ($HNO_3$):
  • In Drawn (Greasy) Image Areas: The nitric acid breaks down the potassium or sodium soaps in the tusche, releasing free fatty acids (such as oleic and stearic acids). These fatty acids chemically bond with the calcium in the stone to produce calcium oleate—an insoluble, hydrophobic (water-repelling), and oleophilic (grease-attracting) compound. This permanently fixes the image into the crystalline pores of the stone.
  • In Bare Non-Image Areas: The nitric acid and gum arabic react with bare calcium carbonate to form a hydrophilic (water-attracting), oleophobic (grease-repelling) layer of calcium arabinate. The gum arabic molecules penetrate deep into the stone pores, creating an invisible, microscopic barrier that bonds strongly with water and fiercely repels oil.

Inking and Printing on the Scraper Press

• The Inking Rhythm: Lithography requires a continuous, synchronized inking cycle involving two tools: a damp cellulose sponge and an inking roller (traditionally a nap leather roller for black ink, or a smooth synthetic rubber/polyurethane brayer):
  1. The printer dampens the entire stone with a wet sponge, laying down a thin, continuous film of water.
  2. The printer rolls greasy, oil-based lithographic ink across the stone.
  3. Because oil and water are immiscible, the moist calcium arabinate film repels the greasy roller ink completely, while the dry, hydrophobic calcium oleate image areas split the ink film from the roller and accept the charge.
  4. The stone must be kept consistently moist; if the stone dries out for even a few seconds during rolling, ink will instantly "catch up" (scum) on bare stone, staining non-image areas.
• The Lithographic Scraper Press: Lithographs cannot be printed on an intaglio roller press or relief platen press. They require a specialized litho press featuring a traveling bed, a flexible fiber tympan sheet lubricated with mutton tallow or lithium grease, and a rigid wooden scraper bar tipped with a strip of stiff leather or polyurethane. As the bed travels under the scraper bar, the narrow edge exerts intense, concentrated scraping and shearing friction across the tympan, forcing damp rag paper against the stone to pull the ink film cleanly.

2. Stencil Printmaking: Serigraphy (Screen Printing) Architecture

Serigraphy (from the Latin seri [silk] and Greek graphein [to write]) is a stencil-based printmaking process. Rather than transferring ink from a block or plate surface, serigraphy uses a rubber blade to force fluid ink through the open apertures of a tightly stretched woven mesh fabric onto a substrate positioned beneath.

Screen Mesh Dynamics and Thread Counts

Modern screen printing utilizes precision woven monofilament polyester mesh stretched tautly (typically 20 to 30 Newtons/cm tension) across a rigid aluminum or kiln-dried hardwood frame:

• Mesh Count (Threads Per Linear Inch): Mesh selection directly controls ink deposit volume, edge sharpness, and resolving power:
  • 85–110 Mesh: Very coarse mesh with wide apertures. Deposits a heavy, thick layer of ink. Ideal for printing opaque textile inks on dark fabrics, puff inks, large flat graphics, or inks loaded with heavy mineral pigments or metallic flakes.
  • 155–195 Mesh: The universal utility workhorse for school printmaking studios. Balances solid opacity with crisp edge definition for paper posters, flat graphic design, and basic typography.
  • 230–305+ Mesh: Ultra-fine mesh with microscopic apertures. Deposits a thin, highly controlled ink film. Essential for high-resolution halftones, delicate photographic prints, multi-color CMYK process printing, and razor-sharp micro-typography without jagged sawtoothing.

Stencil Generation Methodologies

• Direct Photo Emulsion: The industrial and fine art standard. The screen is degreased and coated on both sides with a liquid light-sensitive emulsion (diazo-sensitized polyvinyl alcohol or fast-curing photopolymer) using a specialized trough-like scoop coater. The coated screen is dried in a light-tight darkroom:
  • UV Exposure: A high-contrast film positive (black opaque graphics printed on transparent acetate or vellum) is held in vacuum contact with the dry emulsion and exposed to actinic ultraviolet (UV) radiation.
  • Washout Mechanics: UV light polymerizes and crosslinks the exposed emulsion, rendering it water-insoluble. The unexposed areas protected by the black film positive remain unpolymerized and water-soluble. The screen is washed out with a pressurized water spray; unexposed emulsion dissolves and flushes away cleanly, leaving open mesh apertures corresponding to the original design.
• Direct Hand-Painted Resist (Drawing Fluid and Screen Filler): A classic painterly method ideal for classrooms lacking darkroom UV exposure units. The artist paints positive imagery directly onto bare mesh using water-soluble drawing fluid. Once dry, the entire screen is squeegeed with water-insoluble, acrylic-based screen filler (blockout). After the filler dries, the screen is rinsed with cold water: the water-soluble drawing fluid dissolves and washes away, leaving open mesh where the artist painted, framed by permanent screen filler in all negative spaces.
• Hand-Cut Stencils: Cut from paper, masking film, or self-adhesive vinyl. Adhered to the underside of the screen; useful for bold, geometric, graphic editions.

3. Squeegee Dynamics, Inks, and Printing Execution

The physical transfer of ink through the screen is governed by squeegee mechanics and ink chemistry:

Squeegee Anatomy and Printing Strokes

A screen printing squeegee consists of a firm, molded polyurethane rubber blade mounted into a wooden or aluminum handle:

• Durometer (Blade Hardness): Measured on the Shore A hardness scale:
  • 50–60 Durometer (Soft): Highly flexible, deposits a thick ink layer; ideal for textured textiles and coarse fabrics.
  • 70 Durometer (Medium): The universal studio standard; balanced flexibility and control for paper, cardboard, and fine art editions.
  • 80–90 Durometer (Hard): Rigid blade, minimal ink deposit; required for high-mesh halftone printing and precise four-color process work.
• The Two-Step Printing Stroke:
  1. The Flood Stroke: The screen is held slightly raised above the printing substrate. The printer lightly glides the squeegee across the mesh with low pressure, pulling ink across the image to fill every open aperture. Flooding prevents ink from drying in the microscopic mesh holes and ensures an even ink reservoir.
  2. The Print Stroke: The screen is lowered into contact with the substrate. The printer holds the squeegee firmly at a consistent 45° to 60° angle, applying firm, downward, and forward pressure across the screen. The flexible tip of the polyurethane blade acts as a wiper, shearing the ink across the surface and snapping the taut mesh into contact with the paper to deposit a crisp, clean layer.

Screen Printing Inks: Water-Based vs. Plastisol

• Water-Based Acrylic Inks (e.g., Speedball, TW Graphics): Formulated with acrylic polymer binders and fine pigments suspended in water. Standard in educational studios due to non-toxicity, low VOC emissions, and water cleanup. Dries via evaporation. Critical caveat: if the artist works too slowly or fails to flood the screen between pulls, water-based ink will evaporate and permanently clog the mesh apertures, ruining the stencil.
• Plastisol Inks: Formulated with polyvinyl chloride (PVC) resin particles suspended in a liquid plasticizer. The industry standard for commercial garment printing. Plastisol contains zero water or solvent, meaning it never dries or cures at room temperature and will never clog screens, even if left overnight. However, plastisol must be heat-cured at 320°F (160°C) using a conveyor dryer or flash curer to fuse the PVC molecules into a solid, durable plastic film.

4. Monotype vs. Monoprint: Pedagogical Distinctions

In visual arts pedagogy and ILTS Content Test 214 assessment, the terms monotype and monoprint are strictly differentiated by whether the underlying matrix possesses permanent, repeatable structural marks:

Unique Transfer Taxonomy:
[Smooth, Non-Repeatable Plate] ----> MONOTYPE  (One-of-a-kind unique transfer)
                                       |-> Additive (Light-Field Brushwork)
                                       |-> Subtractive (Dark-Field Wiping)
                                       '-> Ghost Print (Cognate second pull)

[Permanent Incised/Textured Matrix] -> MONOPRINT (Variable unique impression
                                                   from a repeatable matrix)

Monotype (The True Singular Transfer)

A monotype is a strictly unique, one-of-a-kind printed work transferred from an unworked, smooth, non-reproducible matrix (such as a sheet of polished plexiglass, glass, zinc, or gelatin). The matrix contains no permanent physical incisions, etched lines, or carved relief features:

• Additive (Light-Field) Method: The artist works on a clean, light plate, applying printing inks, oil paints, or water-soluble crayons painterly with brushes, rollers, or fingers, creating an image from light to dark.
• Subtractive (Dark-Field) Method: Mastered by Edgar Degas in the 1870s. The artist rolls out a rich, solid, opaque film of dark ink across the entire plate. Using rags, tortillons, cotton swabs, wooden sticks, and palette knives, the artist subtractively wipes away ink to extract luminous highlights and mid-tones, working backward into light.
• The Ghost Print (Cognate): After the initial primary impression is pulled, a faint residue of ink remains on the matrix. The artist can run the plate a second time under the press to pull a pale, spectral transfer known as a ghost print (or cognate). The ghost print frequently serves as an underdrawing for subsequent pastels, watercolors, or mixed-media interventions.

Monoprint (The Variable Series Impression)

A monoprint, by rigorous printmaking definition, is an impression pulled from a matrix that possesses permanent, repeatable structural imagery—such as an etched copper plate, a carved woodblock, an engraved line plate, or a permanent silkscreen stencil—which the artist inks, colors, or modifies uniquely for each individual pull:

• Studio Execution: For example, an artist pulls a series of impressions from an identical etched copper landscape plate, but uniquely hand-inks each pull with variable chromatic rollups (viscosity inking), wipes away plate tones selectively, integrates unique collage paper inlays (chine-collé), or paints unique oil washes onto the plate prior to each press run.
• Result: While each monoprint in the series shares an identical, repeatable structural infrastructure (the etched line work), no two impressions are identical in color, tone, or surface expression.

5. Comparative Matrix: Planographic, Stencil, and Unique Print Media

The following table outlines the matrices, inking chemistry, transfer mechanics, and technical limits across planographic, stencil, and unique print disciplines: