How Carbonless Paper Works

Carbonless paper (also called no-carbon-required paper, or NCR paper) enables duplicate writing or printing without using traditional carbon sheets. It relies on chemically coated layers that react under pressure to produce marks on subsequent sheets.

Key Components & Mechanism:

1. Multi-layer Structure:

   • Typically consists of 2 or more sheets (e.g., top sheet CB, middle sheet CFB, bottom sheet CF).

   • CB (Coated Back): The back of the top sheet is coated with microencapsulated dye (e.g., leuco dye).

   • CF (Coated Front): The front of the lower sheet is coated with a clay or polymer receptor that reacts with the dye.

   • CFB (Coated Front & Back): Middle sheets (if any) have both coatings.

2. Chemical Reaction:

   • When pressure is applied (e.g., writing with a pen or printer impact), the microcapsules on the CB layer rupture, releasing the colorless dye.

   • The dye reacts with the CF layer’s acidic coating, turning it into a visible color (usually blue or black).

3. Result:

   • The exact copy of the original marks appears on the underlying sheets instantly, creating duplicates without carbon smudges.