How do glued NCR pads separate?
How printers glue carbonless paper
- Collate. The printed sheets are stacked in set order: top copy, middle copy if any, bottom copy, then the next set, and so on.
- Knock up and clamp. The stack is jogged so the top edges line up exactly, then clamped.
- Apply adhesive. Fan-apart adhesive is brushed along the edge that will become the top of the pad.
- Dry and fan. Once dry, the stack is flexed or fanned. It comes apart in single sets, each glued at the head.
- Pad up. The sets are gathered in pads, a backing board and cover are added, and the pad edge is glued again to hold the pad together.
Why each set stays together but the next one lets go
Carbonless paper has coatings on specific sides. In a set, the coated back of one sheet sits against the coated front of the next, and the adhesive holds those sheets together. Between sets, the uncoated back of the bottom copy of one set sits against the uncoated front of the top copy of the next. The adhesive is designed not to form a lasting bond there, so the sets release from each other.
That only works when the paper and the adhesive are made to work together and the sets are collated in the correct order. Paper makers describe some grades as designed for self-separating gluing; GiroForm, the carbonless paper we use for our pads, is one of them. If you want to know more about the coatings themselves, How does NCR paper work, and is it the same as carbonless or thermal paper? explains CB, CFB and CF sheets.
Why home-made NCR pads usually fail
- Wrong glue. PVA, spray adhesive and padding glue for plain paper bond every sheet to every other sheet.
- Wrong order. If a set is collated upside down or out of order, it may glue to its neighbour, and the copy will not work either.
- Loose edges. Without clamping and a squared-up edge, the glue line is uneven and sets tear as they come off.
People who print their own forms often hit this after solving the printing problem. If you are thinking of doing both at home, read Can you print on NCR paper with a laser or inkjet printer? first.
How to use a pad without tearing copies
- Slide the cover or a card under the set you are writing on, so the pressure does not mark the sets underneath.
- Write with a ballpoint, pressing firmly, on a hard surface.
- Hold the backing board down and lift the finished set from a bottom corner, peeling towards the glued edge.
- To split the copies, pinch the top edge and pull the sheets gently apart.
If you are designing a form for a pad, keep text clear of the top 15mm, where the glue sits. Anything printed there can be hidden or damaged when the set comes off.
Pad or book?
Pads suit forms where every copy is handed out or filed, such as delivery notes, order forms and kitchen tickets. Cafés and restaurants use them for exactly that, as What size order pad works best for a café or restaurant? explains. If you want one copy kept bound in number order, a book is better. What are NCR pads, and how are they different from NCR books? compares the two, and What should a delivery note include? shows a typical pad layout.
NCR pads that separate cleanly
Discoverprint's NCR pads are printed on 82gsm GiroForm carbonless paper and glued along the top edge to a strawboard back with a white card cover, so each set lifts off whole. Choose A4, A5 or A6, duplicate with 100 sets or triplicate with 50, numbered on every part if you need it. Design is free, pads are dispatched 5 to 6 working days after proof approval, and delivery is free anywhere in Ireland. See the full NCR pads range.
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Frequently asked questions
- How do you glue NCR paper?
- Printers use a special fan-apart adhesive brushed along the edge of a stack of collated carbonless sets. It bonds the sheets within each set but not the sets to each other, so the stack comes apart in single sets.
- Why won't my NCR sets separate?
- Usually because the wrong glue was used, the sets were not collated in the right order, or the paper is not designed for self-separating gluing. Ordinary glues such as PVA bond everything together.
- Can I make NCR pads myself?
- It is possible with carbonless paper, fan-apart adhesive and a way to clamp the stack, but results are unreliable in small quantities. For regular use, printed pads are cheaper and tidier.
- How do I tear off a set cleanly?
- Hold the backing board flat, lift the set from a bottom corner and peel it towards the glued edge, then separate the copies by pulling gently apart at the top.
Sources
- Printing Supplies Direct: GiroForm carbonless paper (self-separating gluing)
- Printing Supplies Direct: How does carbonless paper work?
- Discoverprint: NCR pads (specification)
