In daily office work, financial bills, logistics documents and other scenarios, we often use carbonless paper that can copy multiple copies with one click—it does not require additional toner, ink, or rely on heat. With just a light press, it can quickly present clear text and patterns, and realize synchronous color development of multiple copies. Many people confuse it with thermal paper, but in fact, the coloring principles of the two are essentially different. Today, we will disassemble the coloring magic of carbonless paper, compare its core differences with thermal paper, and understand the underlying logic of these two special papers.

I. Core Structure of Carbonless Paper: Multi-Layer Cooperation Hides the "Coloring Code"

The key reason why carbonless paper can achieve inkless copying lies in its special layered structure and coating design. It is usually divided into single-layer self-sensitive type and multi-layer combined type (the most common is three-layer), which is mainly composed of top paper (CB paper), middle paper (CFB paper) and bottom paper (CF paper). Each layer has a dedicated coating division of labor, which is indispensable:

1. Top Paper (CB Paper, Coated Back Paper): Only a layer of coating (CB layer) containing microcapsules is coated on the back. These microcapsules have a diameter of only 3~7 microns, with a shell made of resin, and the interior is wrapped with carrier oil dissolved with colorless dye (color former). At room temperature, the microcapsules are stable, and the colorless dye cannot overflow, so the surface of the paper appears white.

2. Middle Paper (CFB Paper, Coated Front and Back Paper): It is the "bridge" of multi-layer carbonless paper. The front side is coated with a coating (CF layer) containing color developer, and the back side is also coated with a microcapsule coating (CB layer). This design allows it to not only receive the coloring signal from the upper paper, but also transmit it to the lower paper, realizing the effect of multi-layer copying, and it is also the most costly layer in multi-layer carbonless paper.

3. Bottom Paper (CF Paper, Coated Front Paper): Only a coating (CF layer) containing color developer is coated on the front side, without back-coated microcapsules. Its main function is to receive the coloring signal transmitted from the upper layer, present the final copied content, and serve as the bottom archiving page of multi-layer documents.

In addition, there is self-sensitive carbonless paper (SC paper), which is coated with both color developer and microcapsules on the front side of the same paper, and microcapsule layer on the back side. It can develop color by pressing itself without multi-layer superposition, which is suitable for simple single-layer copying scenarios.

II. Coloring Principle of Carbonless Paper: A "Chemical Encounter" Triggered by Pressure

The core of carbonless paper coloring is "pressure activation + chemical reaction". It does not require heat or ink throughout the process, and only relies on external force (impact force of writing and printing) to complete coloring. The specific process is divided into 3 steps, which are easy to understand:

1. Pressurizing to Break Capsules: When writing with a pen or printing with a dot matrix printer, external force acts on the surface of carbonless paper. The pressure penetrates the upper paper and breaks the microcapsules on the back of the top paper (or middle paper)—these microcapsules are extremely fragile, and even a slight pressure can break their shells.

2. Dye Overflow: After the microcapsules break, the carrier oil of the colorless dye (color former) wrapped inside overflows quickly, seeping through the fiber gaps of the paper to the surface of the CF coating (color developer coating) of the lower paper.

3. Chemical Reaction to Develop Color: The colorless dye undergoes an irreversible chemical reaction with the color developer (mostly acidic substances such as phenolic resin and activated clay) in the CF coating. The molecular structure of the colorless dye changes to form a colored compound, thereby presenting clear text and patterns. Moreover, the color is stable and not easy to fade after development, and can be stably stored for more than 15 years at room temperature.

In short, the coloring process of carbonless paper is: External pressure → Microcapsules break → Dye reacts with color developer → Color appears. It relies on "pressure" to trigger, and multi-layer cooperation can realize one-time writing and synchronous color development of multiple copies, which is the core reason why it is widely used in multi-layer documents.

III. Coloring Principles of Carbonless Paper and Thermal Paper: Core Differences at a Glance

Both carbonless paper and thermal paper are "inkless coloring" papers, which are difficult to distinguish in appearance, but the two have essential differences in coloring trigger conditions, core principles and applicable scenarios. Many people are easy to confuse them. The following uses popular language and clear comparison to help you completely distinguish the two, and clarify their respective applicable scenarios in combination with their core characteristics:

1. Differences in Core Coloring Principles

① Carbonless Paper: Pressure-triggered + irreversible chemical reaction. It relies on the cooperation of microcapsules and color developer. Without heat, it only breaks the microcapsules by the pressure of writing and printing, allowing the colorless dye to react with the color developer. After coloring, the color is stable and not easy to fade, and it can realize multi-layer copying. The reaction process is irreversible, and once colored, it cannot be restored.

② Thermal Paper: Heat-triggered + reversible chemical reaction. It relies on the thermal coating (colorless dye + color developer + sensitizer). Without pressure, it only relies on the high temperature (85~110℃) of the thermal printer to make the colorless dye (such as crystal violet lactone) in the thermal coating react with the color developer to achieve coloring; however, this reaction is reversible. When exposed to high temperature, sunlight and humid environment for a long time, the handwriting will gradually fade and disappear, and it can only realize single-layer coloring and cannot be copied.

2. Comparison of Key Characteristics

① Trigger Condition: Carbonless paper relies on "pressure" (writing, dot matrix printing), while thermal paper relies on "heat" (thermal print head);

② Copying Ability: Carbonless paper can realize multi-layer copying (2~10 copies), and multiple copies can be colored synchronously with one operation; thermal paper can only realize single-layer coloring and cannot be copied;

③ Handwriting Stability: The coloring of carbonless paper is irreversible, and it can be stably stored for many years at room temperature and in a dark environment, which is suitable for long-term archiving; the coloring of thermal paper is reversible, easy to fade, and not suitable for long-term archiving;

④ Equipment Requirements: Carbonless paper needs to be matched with a dot matrix printer (to provide pressure), and thermal paper needs to be matched with a thermal printer (to provide heat);

⑤ Appearance and Environmental Protection: Carbonless paper is mostly a multi-layer combination (different colors for easy distinction), no carbon powder pollution, clean and hygienic; thermal paper is mostly single-layer, with a thermal coating on the surface, some ordinary thermal paper contains bisphenol A, and high-quality products will add a protective layer to reduce pollution.

IV. Summary: Two Types of Paper, Each with Its Own Strengths

Carbonless paper has the core advantages of "pressure coloring, multi-layer copying and long-lasting handwriting". It gets rid of the shackles of carbon powder and ink, and does not rely on high temperature. It has become the first choice for scenarios that require multi-layer archiving such as office documents, financial bills and logistics vouchers; while thermal paper is characterized by "high-temperature coloring, fast printing and simple equipment", which is suitable for scenarios such as supermarket cash register receipts, ATM receipts and express labels that are used for single-layer and short-term use.

Although both are "inkless coloring", their underlying principles are completely different—carbonless paper is a "chemical encounter triggered by pressure", and thermal paper is a "temporary reaction triggered by heat". Understanding the difference between them allows you to accurately choose the right paper according to your own needs, avoiding problems such as document invalidation and archiving difficulties caused by using the wrong scenario.

Casperg Carbonless Paper optimizes the formula of microcapsules and color developers with exquisite craftsmanship, featuring clear color development, smooth copying and long-term archiving, which is suitable for multi-layer document needs in various industries and escorts efficient office work and document management.