NCR paper (No Carbon Required) is a type of paper that is coated with a special layer of micro-encapsulated dye or ink on the back of the top sheet. When pressure is applied to the top sheet, the micro-capsules break, and the dye or ink reacts with a clay coating on the bottom sheet, creating a copy of the original writing or printing.

The exact composition of the coating can vary depending on the specific manufacturer and formulation, but generally, it includes a mixture of chemicals such as:

Micro-encapsulated dye or ink: This is the main component of the coating and is responsible for creating the copy when pressure is applied.

Clay: This is used as a binder and provides a smooth surface for the dye to react with.

Resins: These are used to increase the strength and durability of the coating.

Solvents: These are used to dissolve the resins and other components of the coating to make it easier to apply.

Catalysts: These are used to speed up the chemical reaction between the dye and the clay, ensuring a quick and accurate copy.

Overall, the coating of NCR paper is carefully formulated to ensure that it produces a high-quality copy that is both legible and long-lasting.