Paper and boards.

Paper and boards

Paper and board are selected by their weight, thickness, stiffness, surface, absorbency, printability and ability to fold or crease. These characteristics determine whether a material is suitable for drawing, printing, packaging or structural card products.

Weight, thickness and stock size

Paper weight is normally stated in gsm (grams per square metre). A higher gsm means more mass per unit area and usually a heavier, more substantial sheet. Board is made to a thicker and heavier specification and its thickness can be stated in microns.

Paper is supplied in standard ISO A sizes. Each size is proportionally related to the next, which makes scaling and efficient cutting easier. In commercial printing, larger untrimmed sheets allow artwork to print to the edge before the product is trimmed. Imposition is the arrangement of several pages on a larger sheet so they can be printed, cut and folded efficiently.

Performance characteristics

• Stiffness: important where the material must hold a shape, protect a product or form a carton.
• Compliance: paper can be bent and formed when folded or scored, making it useful for nets, bags and packaging.
• Surface finish: smooth surfaces generally give sharper printing and presentation; textured surfaces can be chosen for appearance or drawing media.
• Absorbency: affects how ink, paint, adhesives and moisture interact with the material.
• Printability: important for graphics, instructions, branding and packaging.
• Folding and creasing: the material must form a controlled fold without unwanted cracking or tearing.
• Moisture resistance: untreated paper and board absorb water, so coatings or laminates may be required for wet environments.

Papers

Material	Characteristics	Suitable applications
Layout paper	Thin, lightweight and slightly translucent	Rapid sketches, overlays and design development
Cartridge paper	Stronger and more substantial drawing paper with a surface suitable for pencils and other media	Drawing, presentation and general design work
Tracing paper	Translucent, allowing an image underneath to remain visible	Tracing, overlays and development drawings
Bleed-proof paper	Treated to reduce marker ink spreading through the sheet	Marker-rendered design work
Treated/coated paper	Surface treatment changes properties such as gloss, water resistance or print quality	Specialist printing, labels and packaging
Watercolour paper	Relatively thick, absorbent and textured	Water-based painting and presentation work

Boards

Corrugated board uses fluted paper between liner sheets. The flutes increase stiffness and provide cushioning without making the package excessively heavy, so it is well suited to transport packaging.

Other boards can be selected for a smoother surface, greater stiffness or presentation quality. The correct choice depends on the required structure, surface finish, printing method and level of protection.

Material choice

Paper and board can be cut, creased, folded, printed and converted efficiently. They can also be recyclable where coatings, laminates, adhesives and contamination do not prevent recovery. A coating may improve moisture resistance or appearance, but the improvement should be balanced against extra processing and possible difficulty in recycling.

A good material justification therefore identifies the specific paper or board and the characteristic that matters. For example, corrugated board suits a transit box because its fluted structure gives stiffness and impact cushioning at relatively low mass.