Print and Packaging Glossary: 60 Terms from GSM to Spot UV
Founder, RoboSouls •
Executive Summary
The print and packaging terms buyers meet most: GSM is paper weight in grams per square metre. Bleed is extra artwork beyond the trim line, usually 3 mm. CMYK is the four-ink process for full colour; Pantone is a standard reference for exact spot colours. A dieline is the flat template of cuts and folds for a box. Spot UV is a gloss coating on selected areas only. Foil stamping applies metallic foil with heat and pressure. Embossing raises a design and debossing presses it in.
Key takeaways
- GSM measures weight, not thickness or quality.
- Supply artwork with bleed (usually 3 mm) and keep text inside the safe area.
- Specify brand colours by Pantone reference; CMYK alone will drift.
- A dieline is the blueprint of a box: every cut, crease and glue flap.
- Finishes change the surface; embossing and debossing change the board itself.
Paper and board
Key Takeaway
GSM is the weight of paper in grams per square metre. Coated papers give sharp, bright print; uncoated papers are better for writing on.
The materials every print and packaging job starts from.
Related: What GSM means, with a paper weight chart
- GSM (grams per square metre): the weight of one square metre of paper or board. Higher GSM is heavier, not necessarily better.
- Caliper: the thickness of a sheet, measured in microns or points. Two papers of the same GSM can differ in caliper.
- Opacity: how little of the print on one side shows through to the other.
- Coated paper: paper with a smooth surface layer that holds ink on top, giving sharp detail. Comes in gloss, silk and matte.
- Uncoated paper: paper without a coating. Softer print, but takes pen, pencil and printer toner well.
- Art paper: a coated paper used for brochures, catalogues and photo pages.
- Bond paper: an uncoated writing paper used for letterheads and forms.
- Paperboard: heavy paper, generally above about 200 GSM, used for cartons and covers.
- FBB (folding boxboard): a paperboard with a coated white top and lighter back, common for monocartons.
- SBS (solid bleached board): paperboard that is white all the way through, for premium and pharma cartons.
- Duplex board: a grey-backed paperboard, used where the inside of a carton is not seen.
- Greyboard: dense, stiff board that forms the core of rigid boxes and hardcover book cases.
- Corrugated board: board with a fluted (wavy) layer between two liners, used for mailers and shipping boxes.
- Flute: the wavy middle layer of corrugated board. Flute sizes trade thickness against print surface and strength.
- Grain direction: the direction most fibres run in a sheet. Paper folds more cleanly along the grain.
Artwork and prepress
Key Takeaway
Bleed is artwork that extends past the trim line so no white edge shows after cutting. A proof is a check copy approved before the run.
Terms that come up when artwork is prepared and approved for print.
Related: Print-ready artwork checklist
- Trim size: the final size of a printed piece after cutting.
- Bleed: artwork extended beyond the trim line, usually 3 mm, so no white edge shows after cutting.
- Safe area: the zone inside the trim where text and logos should stay, away from the cut.
- CMYK: cyan, magenta, yellow and key (black), the four process inks that combine to print full colour.
- Pantone (PMS): a standard colour reference system used to specify and match exact spot colours.
- Spot colour: a single pre-mixed ink printed in its own pass, used to hit a brand colour exactly.
- Resolution: image detail, measured in dots per inch. Print usually needs about 300 dpi at final size.
- Proof: a copy of the job checked and approved before the full run. A physical or hard proof shows real colour on paper.
- Imposition: arranging pages or boxes on the press sheet so they print and fold correctly.
- Signature: a large sheet printed with many pages that is folded into one section of a book, often 16 pages.
Printing
Key Takeaway
Offset printing transfers ink from a plate to a rubber blanket to the paper, and suits medium and long runs. Digital printing prints directly from a file and suits short runs.
How ink gets onto paper.
Related: Offset vs digital printing
- Offset printing: ink passes from a metal plate to a rubber blanket and then to the paper. Consistent colour on medium and long runs. RoboSouls prints offset in-house on sheets up to 28 × 40 inches.
- Digital printing: printing directly from a file without plates. Suits short runs and personalised items.
- Plate: the metal sheet carrying the image for one ink colour on an offset press.
- Registration: how precisely the colours, cuts and finishes line up with each other.
- Make-ready: setting up the press before a run, the same work whatever the quantity.
- Overprint: printing one colour on top of another rather than leaving a gap for it.
Finishing
Key Takeaway
Lamination is a film bonded to the sheet; UV coating is a liquid coating cured by UV light. Spot UV is gloss on selected areas. Foil stamping applies metallic foil with heat and pressure.
What happens to a printed sheet to protect it or make it premium. RoboSouls does all of these in-house.
Related: Packaging finishes compared
- Lamination: a thin plastic film bonded to the printed sheet, in gloss, matte or soft-touch.
- Soft-touch lamination: a matte laminate with a velvety feel that resists scuffing.
- UV coating: a liquid coating cured instantly by ultraviolet light, giving gloss and protection.
- Spot UV: UV coating applied only to selected areas, such as a logo, for contrast against a matte surface.
- Aqueous coating: a water-based protective coating applied across the sheet.
- Varnish: a clear coating applied on press, flood (all over) or spot.
- Foil stamping: metallic or coloured foil pressed onto the sheet with a heated die.
- Embossing: pressing a design up from the back so it stands raised on the surface.
- Debossing: pressing a design down into the surface.
- Blind emboss or deboss: an emboss or deboss with no ink or foil, read by touch and shadow.
- Die-cutting: cutting a printed sheet to a shape with a steel-rule die.
- Creasing: pressing fold lines into board so it folds cleanly without cracking.
- Window patching: gluing a clear film behind a cut-out window in a carton.
Binding
Key Takeaway
Saddle stitching staples folded sheets through the spine. Perfect binding glues pages to a spine. Section sewing stitches each signature, so the book opens flat.
How pages are held together in brochures, catalogues, books and diaries.
Related: Coffee table book specs: paper, binding and cover
- Saddle stitch: folded sheets stapled through the spine. Needs a page count divisible by four.
- Perfect binding: page edges glued to a square spine, as in most paperbacks and thicker catalogues.
- Section sewing: each folded signature stitched through its fold, then bound. Opens flat.
- Case binding: a sewn book block bound into a hard cover made of board and wrap.
- Wiro or spiral binding: pages held on a wire coil, so the book folds right back.
- Gutter: the inner margin of a page, where it meets the spine.
Packaging structures
Key Takeaway
A dieline is the flat template of a box. A monocarton is a single-piece paperboard box; a rigid box is greyboard wrapped in paper; a mailer is a corrugated shipping box.
The boxes, and the parts of them, that come up in packaging briefs.
Related: What is a monocarton? · Rigid box vs monocarton vs mailer box
- Dieline: the flat template showing every cut, crease and glue area of a box.
- Monocarton (folding carton): a single-piece paperboard box that ships flat and folds at packing.
- Rigid box: a set-up box of greyboard wrapped in printed paper, used for premium presentation.
- Mailer box: a die-cut corrugated box with a tuck-in lid, for shipping and unboxing.
- Magnetic closure box: a rigid box whose flap is held shut by hidden magnets.
- Insert: the tray or fitment inside a box that holds the product in place.
- Tuck end: a carton closure where a flap tucks into the box. Reverse and straight tuck are the common styles.
- Lock bottom (crash lock): a carton base that folds and locks to carry a heavier product.
- Sleeve: a printed wrap that slides over a box or tray.
- Outer (shipper): the corrugated box that carries several retail cartons in transit.
Summary Overview
Most misunderstandings in a print or packaging job come from two people using the same word differently. Keep this glossary next to the next quote or proof you review, and send any term it does not cover to RoboSouls with your brief.
Frequently asked questions
What does GSM mean in printing?
Grams per square metre: the weight of one square metre of paper or board. It measures mass, not thickness or quality.
What is bleed in printing?
Artwork that extends beyond the trim line, usually by 3 mm, so that no white edge is left when the sheet is cut to size.
What is a dieline?
The flat template of a box or shaped piece, showing where it is cut, creased and glued. It is made to the product's dimensions before artwork is placed on it.
What is the difference between spot UV and UV coating?
UV coating covers the whole sheet. Spot UV applies the same gloss coating only to selected areas, such as a logo, so they stand out against a matte surface.
What is the difference between embossing and debossing?
Embossing raises a design above the surface; debossing presses it into the surface. Either can be done blind, with no ink or foil.
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