Offset paper, fully known as double-sided offset printing paper, is also referred to as offset printing paper or "Daolin paper" (named after its early introduction from the Daolin Company in Hong Kong). Its primary raw material is wood pulp, while the key auxiliary material — which determines the "offset" characteristics — is sizing agent (such as starch, PVA, AKD, etc.). The function of the sizing agent is to provide water resistance, prevent ink bleeding, and reduce linting. The core feature is double-sided sizing, ensuring that both sides of the paper are flat, water-resistant, and free of powdering. In English, it is generally called woodfree offset paper or uncoated woodfree paper.

High-grade offset paper is made from 100% virgin wood pulp (a mix of softwood and hardwood). Medium-grade offset paper is primarily virgin wood pulp with a small amount of fillers. Some low-grade offset paper may include a small proportion of recycled pulp (wastepaper pulp) or non-wood fibers such as straw pulp or bamboo pulp.

Since there is double-sided offset paper, there is also single-sided offset paper (which can only be printed on one side, as the other side is prone to linting, show-through, and wrinkling).

Offset paper is the most commonly used uncoated paper for printing and writing. Its characteristics are as follows:

1. Strong printability — Low dimensional change; uniform ink absorption; smooth surface.

2. Stable physical properties — High opacity; good strength; good water resistance; uniform whiteness.

3. Texture and cost — Soft and comfortable feel; wide basis weight range; high cost-performance ratio.

4. Main applications — Books, textbooks, magazine covers; picture albums, instruction manuals, posters, maps; office paper, forms, envelopes, notebooks.

Differences Between Offset Paper and Coated Paper

The base pulp of offset paper and coated paper is not significantly different. The base paper of both types is mostly composed of softwood pulp (long fibers, providing strength) and hardwood pulp (short fibers, providing smoothness), both primarily wood pulp.

The core difference lies in the presence of a "coating layer." Offset paper has no coating layer; it only receives sizing treatment on both surfaces (with starch, PVA, or other sizing agents) to achieve water resistance, prevent ink bleeding, and reduce linting. Its base material remains paper fibers. Coated paper, on the other hand, has a distinct and relatively thick coating layer. The coating fills the surface and is then calendered to create a smooth, glossy, mirror-like finish.

Simply put:
Offset paper = wood pulp + double-sided sizing
Coated paper = base paper + coating layer

In addition, the following differences exist:

1. Surface texture

   • Offset paper: Fine texture, non-reflective, natural matte finish, feels like ordinary paper.

   • Coated paper: Feels like it has a layer of oil — smooth, glossy, firmer, and flatter to the touch.

2. Printing effect

   • Offset paper: Ink is absorbed into the paper. Text is clear and comfortable for long reading sessions. Images appear softer.

   • Coated paper: Ink sits on the surface, producing vivid colors and high saturation. Photos and illustrations appear highly detailed and refined.

3. Paper surface coating

   • Offset paper: No coating — only double-sided sizing. Strong fibrous feel.

   • Coated paper: Has a coating layer (white mineral coating).

4. Application scenarios

   • Offset paper: Preferred for book interiors, novels, textbooks, contracts, notebooks, instruction manuals.

   • Coated paper: Preferred for art albums, brochures, posters, magazine covers, high-end product catalogs, business cards.

The simplest and most direct way to distinguish them: hold the paper up to the light. If it does not reflect light, it is offset paper. If it shines or reflects light, it is coated paper.