Carbonless copy paper has revolutionized the way we create copies of documents without the need for carbon paper. In the past, carbon paper was used to create duplicates of handwritten or typed documents. However, with the advent of word processors and nonimpact printers, carbon copies have become increasingly rare in correspondence and memos.

The key principle behind carbonless copy paper is the use of an emulsion oil-carried color former that is encapsulated in microcapsules. These microcapsules are applied as a coating on the backside of the copying paper. When pressure is applied through writing, the microcapsules are broken, causing the color former solution to flow onto the front side coating of a receiving sheet. The front side coating then reacts with the color former, creating an image.

This innovative principle was originally patented by National Cash Register (NCR), who named the method NCR (no carbon required). While the NCR patent was in effect, other systems were developed and marketed. However, once the patent expired, the NCR principle was widely copied, leading to the development of carbonless copy paper as a commodity with multiple suppliers. Today, the market for carbonless copy paper has matured.

The sheets in a set of carbonless copy papers are designated based on their coating and position in the set. The top sheet that receives the original writing is known as CB or coated back. The bottom sheet, which only receives an image, is called CF or coated front. The middle sheets, which also receive and pass on an image, are referred to as CFB or coated front and back.

Carbonless forms are preprinted using methods such as normal offset or web offset printing. By printing an inhibitor on certain fields, copying can be selectively prevented, adding a layer of security to the documents.

To create sets of forms, the printed forms can be collated in the desired sequence and cut. A watery glue is then applied to the side of the pile of forms, which enters between the CB and CF coated surfaces, bonding them together. This leaves the uncoated top of the top sheet and bottom of the bottom sheet dry. This effect is achieved by making the coatings hydrophilic and hydrophobic, selectively sizing the uncoated surfaces.

The majority of carbonless copy paper is used in continuous stationery form printers, where security and backup copies are required. Continuous forms are preprinted using web offset or flexo printing, and the rolls are collated in roll collating machines. To ensure proper operation, it is important for the rolls to have an equal length. Dimensional stability, internal tensions, and controlled humidity are crucial factors in this process.

Carbonless copy papers are primarily produced on normal fine paper machines, with the CF coating applied on-line using blade coaters. In order to preserve the microcapsules, the CB coating is applied using airbrush or softer methods. The basis weights for CB are typically around 50-70 g/m2, which is lighter than normal stationery papers to allow for better pressure transfer. Base sheets for CFB are about 40 g/m2, resulting in a 50 g/m2 sheet with coatings. The CF bottom sheet can be made independently of pressure transfer, and a heavier 70-120 g/m2 sheet is often used to provide stability to the form set.

While carbonless copy paper was once made in different colors to distinguish the form layers, this practice has declined due to the ability to print in various colors for the same purpose.

In conclusion, carbonless copy paper has significantly changed the way we create duplicate documents. Its innovative technology and widespread availability have made carbon copies a thing of the past. Whether it is used in office forms or continuous stationery form printers, carbonless copy paper continues to play a crucial role in creating reliable and efficient copies.