Bookbinding apprentice preparing paper sheets at a workbench
Apprentice in bookbinding, preparing signatures at a workshop bench. Wikimedia Commons, public domain.

A signature — also called a gathering or quire — is a group of paper sheets folded together to form a section of a sewn book. When multiple signatures are assembled and sewn in sequence, they produce the book block that is then attached to covers. The quality of folding directly affects how the finished notebook opens, how the pages lie flat, and how long the binding lasts.

Before any sewing can begin, signatures must be prepared with attention to paper grain, consistent sheet count, clean folds and aligned edges. These steps are taught at the start of bookbinding courses in Polish craft workshops because errors at this stage compound through every subsequent operation.

Understanding Paper Grain

Machine-made paper has a grain direction determined by the alignment of cellulose fibres during manufacture. Folding parallel to the grain produces a sharp, stable crease. Folding across the grain produces a rough, ridged fold that resists lying flat and tends to spring open.

In a bound book, grain must run parallel to the spine — vertically along the bound edge. When grain runs across the spine, the book warps as it absorbs and releases moisture, and individual signatures develop a permanent outward bow at the page edges.

Testing for Grain Direction

Three practical tests can be used without specialist equipment:

  • Bending test: Hold a sheet horizontally by two edges and allow it to flex under its own weight. Turn the sheet 90° and repeat. The sheet bends more readily parallel to the grain.
  • Tear test: Tear a small strip across both axes. The grain direction produces a straighter tear; the cross-grain direction produces a ragged edge.
  • Moisture test: Dampen one corner of a sheet with a wet finger. The sheet curls parallel to the grain direction.

Standard copier paper sold in Poland (80 g/m², A4) is manufactured with grain running parallel to the long side of the sheet. This means that for A5 notebooks bound on the short edge, sheets must be cut so that the long side becomes the spine edge.

Selecting Sheet Count per Signature

The number of sheets per signature affects the curvature of the spine and the ease of sewing. Practical ranges are:

Common Signature Configurations

  • 4 sheets (8 leaves, 16 pages): Standard for most hand-bound notebooks. Produces a flat spine and easy hole-punching.
  • 5 sheets (10 leaves, 20 pages): Slightly thicker. Acceptable with lightweight paper up to 90 g/m².
  • 6–8 sheets: Used only with papers below 70 g/m². Heavier papers in this count produce bulging signatures that are difficult to sew evenly.

Polish craft workshops teaching Coptic stitch typically standardise on 4-sheet signatures. Japanese stab binding, which treats the entire book block as a unit, does not use signatures at all — instead, single sheets are stacked directly.

Cutting Sheets to Size

Sheets are cut before folding. A rotary trimmer (gilotyna) produces cleaner edges than scissors and is standard equipment in most bookbinding workshops. The cutting order matters: long cuts first, then short cuts, keeping the grain orientation in mind throughout.

All sheets intended for a single notebook should be cut in one session from the same ream of paper. Paper from different reams — even nominally identical stock — can vary slightly in weight and texture, which affects how signatures nest together when sewn.

Folding Technique

  1. Stack the sheets for one signature, aligning all four corners. Hold the stack lightly to prevent slipping.
  2. Bring the top edge down to meet the bottom edge, creasing gently at the midpoint with your fingertip before committing to a full fold.
  3. Confirm the fold is straight and the corners are aligned before pressing down firmly.
  4. Open the signature slightly and place it on a flat surface with the fold facing away from you.
  5. Run a bone folder firmly along the full length of the fold in a single smooth stroke. Repeat from the other end.
  6. Flip the signature and repeat the bone folder pass on the other side of the fold.

The bone folder compresses the fibres at the fold, producing a crease that resists spring-back. A fingernail or the back of a spoon can substitute in the absence of a bone folder, but the result is less consistent.

Pressing and Collating

Freshly folded signatures should be pressed under weight — a stack of books or a dedicated finishing press — for at least 30 minutes. Pressing flattens the fold and allows the paper to settle before punching.

After pressing, signatures are collated in order and checked for consistent spine alignment. Any signature that sits higher or lower than its neighbours will create an uneven spine when the book is sewn. Misaligned signatures can be re-folded; once punched and sewn, misalignment cannot be corrected without disassembling the book.

Numbering Signatures

For books with more than five or six signatures, light pencil numbering on the inside of the first fold helps maintain the correct sequence during sewing. The number is placed inside the fold so that it does not appear on the finished page.

Preparing Covers

For multi-signature bindings such as Coptic stitch, cover boards are prepared alongside the signatures. Grey board at 2 mm thickness is the standard in Polish craft workshops for A5 format. The board is cut slightly larger than the page size — typically 3–4 mm overhang on the top, bottom and fore-edge — and covered with book cloth or decorative paper before sewing begins.

The cover boards are punched at the same hole positions as the signatures so that they integrate directly into the sewing sequence without requiring separate attachment after the fact.

References and Further Reading