The pen touches the top sheet. The writing appears on the sheets beneath it too. Yet there is no loose sheet of carbon paper between the pages.
In a carbonless form, the extra marks are made by coatings on the paper responding to pressure. The ink from the pen makes the original; the prepared layers make the copies. Knowing that distinction helps when a lower copy is faint, a set has been rearranged or a new form is being specified.
The useful question is not simply how many sheets a pad contains. It is which sheets form one complete set, what each layer does and whether the information reaches the last person who needs a copy.
The copy is made at the meeting of two coatings
Paper manufacturer Koehler describes a system in which pressure breaks microscopic capsules containing a colour-forming substance. That material meets a reactive coating on the sheet below and produces a mark. Writing is one way of applying the pressure. An appropriate impact-printing process can do it too. Koehler’s explanation of carbonless copying sets out the mechanism.
The top and bottom sheets are therefore doing different jobs. A stack of ordinary blank paper does not become a carbonless set just because a pen presses through it. The receiving coating is part of the system, as is the material that creates the mark.
Nor is a vivid pen line on the top sheet proof that every lower sheet received a useful copy. Those are two different observations. The original may be clear while a lower part needs attention.
Three paper codes describe three roles
The abbreviations used in a conventional multi-part set are easier to understand when read as descriptions of coated sides:
- CB — coated back: the top sheet supplies the colour-forming material from its back.
- CFB — coated front and back: a middle sheet receives a copy on its front and passes the action onward from its back.
- CF — coated front: the final sheet receives the last copy on its front.
Koehler’s technical explanation describes the top, middle and end sheets. The middle sheet has two roles, which is why it is not interchangeable with a plain sheet.
A two-part conventional set can use a top and end sheet. A set with more parts needs the appropriate middle layer or layers. Confirm the actual product rather than treating the abbreviations as a universal recipe for every specialist paper.
There are exceptions. Koehler also describes self-contained paper, in which the ingredients for the reaction are together in one surface coating. Such products can work with an ordinary top sheet. That self-contained arrangement is a reason to identify the supplied paper before diagnosing it by appearance alone.
A colour sequence is not the mechanism
White, yellow and pink sheets make a multi-part form easy to recognise. The colours can help users distinguish copies and their destinations. The coatings, rather than the colour of the base paper, make the copy.
Do not assume that a yellow sheet always belongs in the middle or that a pink one always belongs at the bottom. Check the specified set and retain its order. Colours and available combinations depend on the product being supplied.
If an old form is being replaced, identify which copy goes to whom. “Three parts” describes a physical count. “Customer, office and delivery record” describes what those copies need to achieve. Use the actual recipients relevant to the job rather than borrowing those example labels automatically.
A book, a pad and a set are different things
One set is the group of sheets involved in a single completed form. Several sets may be supplied together in a pad or book. The binding and removal arrangements affect how the copies are handled afterwards.
Caralan’s trade NCR specifications, for example, distinguish loose sets, pads from which the parts are removed and books that can retain a bottom copy. Those are that supplier’s arrangements, not a rule that every printer uses the same terminology or construction.
When requesting a repeat, describe what should happen in use. Does the complete set leave the pad? Does one part stay in the book? Must a recipient tear out one copy while another remains? Agree the construction as well as the number of parts.
The same supplier explains a practical detail that is easy to overlook: a writing shield goes beneath the active set to prevent marks reaching unused sets below it. Follow the instructions for the supplied book or pad, rather than assuming the whole stack is meant to receive the pressure.
Check the last copy, not only the original
Before adopting a new form layout, complete a representative sample in the way it will actually be used. Look at each part separately, including the last one.
Check a short word, a number and any small box that needs a mark. Is there room to write without drifting outside the field? Do the copied marks remain understandable where they are needed? Does each recipient receive the necessary information?
This is a practical use check, not a guarantee that one successful sample covers every pen, writing style or future batch. If a lower copy is weak, describe the exact set, writing method and observed result to the supplier. Do not immediately solve the problem by changing the paper order or making an unverified production adjustment.
Keep the blank sample and the agreed specification together. A photograph of the top sheet alone will not show whether the lower copies were useful.
Printed information and copied information need separate attention
The fixed form artwork and the marks added during use are different layers of information. Decide which headings, instructions and recipient labels must be printed on each part, rather than assuming that everything important will transfer from the handwriting.
An office copy may need a different fixed instruction from the customer’s copy. If the parts differ, supply a clearly identified version for each. Check that writing fields still align through the set.
The pressure-sensitive copying process also does not establish that any carbonless stock belongs in an office laser printer. Koehler makes a specific reacto LASER range for toner-based digital printing. That product distinction is a reason to check paper and printer compatibility, not permission to use an unidentified pad as printer stock.
A brief that describes the complete form
A useful enquiry record can separate these questions:
- What is one completed form used for?
- How many parts are needed, and who receives each?
- Which fixed wording appears on every part, and what differs?
- Which parts detach and which, if any, remain bound?
- Is numbering required, and where should it appear?
- How will the form be completed: by hand or through a specified compatible process?
- What sample or proof will be checked before agreement?
This is an editorial preparation list. It does not establish a supplier’s capabilities, available paper, numbering method or production terms. Those need confirmation for the actual job.
The cleverness of carbonless paper is concealed in a familiar action. One stroke can make several records because the sheets have been prepared to work together. The useful specification is the one that keeps that whole set working—not merely the sheet the pen touches.
Sources and scope
Koehler’s linked technical explanation and laser-product page support the coating and paper distinctions. Caralan’s specifications provide explicitly attributed examples of binding and writing shields. The layout and sample-check suggestions are practical editorial guidance. No legal retention period, security guarantee, archival life, universal copy limit or unverified Time for Designs carbonless-printing offer is claimed.