Fan apart carbonless sets are business forms that stick together in individual sets rather than a pad of multiple sets.
Take for example a 2 part invoice. You have a top copy for the customer and a bottom copy for the retailer. This is what is called a ‘set’ and the two sheets stick together. However, they do not stick to the the next 2 part set in the box of invoices. This way you do not have to keep pulling them apart.
Whilst the top and bottom sheets stick together they will not stick to any other sheet of paper.
It is really clever how fan apart carbonless sets stick together without gluing to the next set. However, to understand it you first need to know how the carbon copy is made.
Basically, the top sheet has a special carbonless chemical coating on the back of it. It is invisible to the eye but you can feel it is different from the front of the sheet. Where as, the bottom sheet has a special invisible chemical coating on the front of it. Put them together and nothing happens. However, add pressure and the carbon copy is made. The pushing together on the two chemical surface causes the bottom copy to change colour where the pressure is applied. So when you use a pen on the top copy an exact replica of your writing in made on the bottom sheet.
Now We Add the fan Apart Carbonless Glue to the Equation
This glue reacts with the chemical coating on the back of the top sheet and the front of the bottom sheet. It causes the two sheets of carbonless paper to stick together. However, because there is no chemical coating on the back of the bottom copy or the front of the next top copy in the pile it will not glue them together. This way you can sack thousands of two part invoices together and glue them all in one go. You do this by painting on the fan apart adhesive with a brush. Then when the glue drys those same thousands of invoices only stick together in 2 part sets and not into on big block or pad.