RRB JE Printing Press — Complete CBT-2 Study Guide

• Major printing processes: Offset (Lithography) — image and non-image areas are on the same plane, separated by an ink-water repulsion principle (oil-based ink adheres to image area, water to non-image area); most widely used commercial printing method for books/newspapers/packaging. • Letterpress — a relief printing process where the image area is raised above the non-image area (direct ink transfer from raised type/plate to paper) — largely historical now but foundational to print technology. • Gravure (intaglio) printing — image area is recessed/engraved below the surface as tiny cells that hold ink; used for very long print runs (magazines, packaging) due to high setup cost but excellent, consistent quality at volume. • Screen printing — ink is forced through a mesh stencil onto the substrate; suited for printing on non-paper surfaces (textiles, plastics, glass, metal) and for very thick/opaque ink deposits. • Digital printing (inkjet/laser/toner-based) — no physical printing plate required, cost-effective for short runs and variable data (each printed piece can differ), but generally higher per-unit cost than offset at high volumes.

• Color models: CMYK (Cyan, Magenta, Yellow, Key/Black) is subtractive, used for PRINT — colors are created by subtracting light via ink absorption; RGB (Red, Green, Blue) is additive, used for SCREENS/digital display — colors are created by adding light. • Resolution: measured in DPI (Dots Per Inch) for print — higher DPI gives finer detail; standard commercial print resolution is typically 300 DPI for photographic images, lower (150 DPI or so) acceptable for large-format/poster work viewed from a distance. • Halftone printing simulates continuous-tone images (like photographs) using varying-sized dots of a single ink color — larger/denser dots appear darker, smaller/sparser dots appear lighter to the human eye at normal viewing distance. • Prepress workflow: Typesetting/Layout → Color Separation (splitting a full-color image into its CMYK component plates) → Plate-making (exposing the printing plate with the image) → Proofing (checking color/layout accuracy before the full production run). • Trapping (in prepress) is a slight, deliberate overlap between adjacent colors to prevent visible white gaps if the printing plates are ever so slightly misregistered/misaligned during the press run.

• Paper is manufactured mainly from wood pulp via two processes: Mechanical pulping (grinds wood fibers, cheaper, retains lignin — yellows/degrades faster, used for newsprint) vs Chemical pulping (e.g. Kraft process, dissolves lignin chemically, produces stronger, longer-lasting paper used for books/quality printing). • GSM (Grams per Square Meter) measures paper weight/thickness — higher GSM means thicker, heavier, more rigid paper (e.g. ~70-100 GSM for standard book/office paper, 250+ GSM for card stock/covers). • Paper grain direction (the alignment of fibers during manufacturing) affects fold quality and stiffness — folding WITH the grain gives a cleaner, crisper fold than folding against it, which can crack the paper surface. • Paper finishes: Coated (clay/polymer-coated surface, gives glossy/matte photo-quality reproduction, common for magazines) vs Uncoated (natural fiber surface, more ink absorption, common for books/stationery, easier to write on). • Recycled paper content and de-inking (removing old ink from recycled fiber before repulping) are increasingly relevant sustainability topics in modern printing/paper technology.

• Bleed is the extra margin of image/color extending beyond the final trim line of a printed piece — ensures no unprinted white sliver appears at the edge if trimming is very slightly off-position; standard bleed allowance is typically 3mm. • Registration marks (crosshair marks outside the trim area) help align multiple color plates precisely during a multi-color print run — misregistration causes visible color fringing/blurring on the final printed piece. • Typography basics: Serif fonts (with small decorative strokes at letter ends) are traditionally considered easier to read in long printed body text; Sans-serif fonts (without these strokes) are often preferred for headlines, digital screens, and modern/clean design aesthetics. • Color separation and spot colors: Process colors (CMYK) can reproduce a huge range of colors by combining four inks; Spot colors (e.g. Pantone-matched inks) use a single pre-mixed ink for exact, consistent brand-color reproduction that CMYK process printing cannot always match precisely.