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1. Composition of Paper
Paper is a material processed from plant fibers combined with fillers, sizing agents, colorants, and other components.
2. Raw Materials for Paper
Primary raw materials include straw, bamboo, wood, cotton, linen, and reusable waste materials. The properties of the paper formed will vary depending on the raw materials used. Straw, bamboo, wood, cotton, linen, and reusable waste materials refer to plant fibers, while fillers, sizing agents, and colorants are auxiliary components.
3. Fillers
Fillers are materials used to enhance the flexibility of paper, reduce its transparency and elasticity, and make its surface smooth and uniform. Examples include talcum powder for general printing paper, kaolin and barium sulfate for high-grade paper. The use of fillers should be moderate, generally accounting for about 20% of the paper's composition. Excessive filler usage can reduce the resistance and flexibility of the sheet, hinder ink absorption, and cause powder shedding during printing.
4. Sizing Agents
Sizing agents are used to fill small pores in the paper, enhancing its water resistance. They also improve the gloss and strength of the paper and prevent the paper surface from fuzzing. Common sizing agents include rosin, alum, and starch.
5. Pigments
Pigments are used to enhance the color purity of the paper. Inorganic pigments or organic dyes are commonly employed for this purpose.
6. Specifications of Paper
Paper can be classified into flatbed paper and web paper based on different printing purposes. Flatbed paper is suitable for general printing machines (books, picture albums), while web paper is generally used in high-speed rotary printing machines (newspapers).
7. Paper Size Units (K)
K represents the paper separation unit and is a fundamental term in advertising agencies. For example, 8K and 16K refer to dividing a full sheet of paper into 8 or 16 equal parts, respectively.
8. Paper Dimensions
- Magnanimity: 889*1194 (mm)
- Full Sheet (1K): 840*1140 (mm)
- Double-Sized (2K): 570*840 (mm)
- 4K: 420*570 (mm)
- 8K: 285*420 (mm)
- 16K: 210*285 (mm)
- 32K: 143*210 (mm)
9. Paper Grammage
Grammage is an important parameter for paper, indicating its thickness. Common examples include 80g and 157g offset paper. Higher grammage indicates thicker paper, while lower grammage indicates thinner paper. The unit of grammage is g/m².
10. Offset Paper
- 70g and 80g: Suitable for ordinary printing, manuals, and book interiors.
- 100g: Ideal for better-quality manuals, high-end book interiors, and envelopes.
- 110g and 120g: Primarily used for envelopes and file folders.
- 140g: Rarely applied due to its limitations in offset printing.
11. Coated Paper
Coated paper is widely used in color printing, such as picture albums, posters, single pages, and brochures. It is divided into glossy coated paper and matte coated paper.
- 105g and 128g: Minimum weights for four-color printing on both sides. Suitable for magazine interiors, inserts, and low-grade promotional materials.
- 157g: Most commonly chosen weight for ordinary single-page printing. Widely used for advertising leaflets, brochures, posters, etc.
- 200g and 250g: Preferred by large companies and quality-conscious customers. Suitable for high-quality single pages, posters, album covers, cards, packaging boxes, etc.
- 300g and 350g: Less commonly used due to overlapping functionality with cardstock. Suitable for album covers, business cards, invitations, packaging boxes, handbags, etc.
- 400g: Rarely used in practical applications. Suitable for invitations, business cards, covers, handbags, etc.
12. Whiteboard Paper
Whiteboard paper is a type of coated cardboard with a smooth front, divided into white base whiteboard and gray base whiteboard.
- White Base Whiteboard: Smooth front and relatively rough back; both sides can be printed in four colors.
- Gray Base Whiteboard: Smooth and white front, gray back; front can be printed in four colors, while the back is mostly single red.
Usage: Packaging boxes for food, medicine, etc., with medicine being the most common application.
13. Cardstock
Cardstock is a single-sided high-gloss coated paper processed from paper of different basis weights or whiteboard paper. It is mainly used for printing trademarks of high-end goods, exquisite handicrafts, packaging, postcards, greeting cards, business cards, invitations, etc. Its flatness and glossiness surpass those of coated paper.
14. Corrugated Paper
Corrugated cardboard is made by processing corrugated base paper into a wavy shape and gluing cardboard or paper on both sides. It is lightweight but has good strength, stiffness, elasticity, and shock absorption properties. Common uses include packaging boxes, small household appliances, and large electrical equipment.
15. Specialty Paper
Specialty paper plays a crucial role in modern printing, emphasizing individuality and creativity. Examples include sulfate paper (butter paper), quicksand paper, deer pattern paper, etc. Due to the numerous forms of specialty paper, it is impossible to cover all types comprehensively. Practical printed materials and paper samples are used to teach trainees about the particularity of specialty paper.
16. Paper Units
- Rei: One rei consists of 500 full-sized sheets of paper. Quotations to customers are calculated per order.
- Ton: Paper purchasing unit.
- Accuracy: 1884 ÷ grammage = Number of grams of paper that can be produced from one ton.
- Magnanimity: 2320 ÷ grammage = Number of grams of paper that can be produced from one ton.
