Imposition

Imposition, not to be confused with the term exclusion ( hot type ), the specific arrangement of the sides of a printing form in the way that the printed and folded sheet gives the correct order of the page numbers. The sides need to keep the pressure register and vote after cutting the sheet and folding in the sequence. The imposition results from the format of the print and the type of bookbinding finishing. The most common binding methods Saddle, perfect binding, sewn binding and loose-leaf collection should be mentioned. In the field of the roller pressure are other special methods are used.

In the factory set 16 printed pages are usually arranged on a folded sheet, which corresponds to eight pages in perfecting printing. This indicates the benefit, how many bookbinders sheet of printed sheets is exploited. If on a press sheet of 16 pages arranged so this is once in 32 disposed sides, it is used twice.

The trimming is the edge which is also required in order to curtail the book block after the pressure. Here also the gripper edge of a sheet printing machine must be taken into account.

Furthermore, imposition, a term for the removal of the unprinted intermediate sheet that are placed against the set-off between the fresh sheet. The insertion of these intermediate sheet is called zeroing.

The example above shows the site distribution for a 16-page booklet. Eight pages come to the front side and eight on the back. After printing, the paper first is folded vertically ( side two falls on page three), then horizontally ( side four falls on page five ), and then again vertically (page nine falls on page eight). The following figure shows the result before binding and trimming.

Folds

The position and orientation of the pages on the sheet is first by folding scheme being used. The most common Falzfolgen are two break - cross-fold ( folded sheet with eight pages) and three-fold - cross-fold ( folded sheet with 16 pages). For products that consist of more pages than to a pressure or signatures match, also the collection process is important ( to collect deposits or multi-layer brochures ).

Imposition is exclusively computer-assisted in the production of CTP printing plates. For the standard Falzfolgen Imposition schemes are usually permanently stored in the imposition software. More folding layouts can be entered for, among other things with the help of Falzkatalogen. Meanwhile, the positioning and orientation of the pages can also be solved algorithmically. Well-known computer programs for imposition are ApogeeX ( AGFA ), Prinect Signa Station ( HEIDELBERG ) Preps (Kodak), GRAPHIAware Nicola ( GRAPHIA ) or Imposition Publisher ( Farrukh Systems ). Especially for nesting optimization, Metrix ( Lithotechnics ) is suitable.

During imposition must be considered, such as the sheet is printed. The most common options are the obverse and reverse pressure, turning, turning ( pressure), the eversion or nesting.

In determining the Falzschemas to be used is the running direction of the paper, that is, whether wide, narrow or machine train to note. This is an important criterion when further processing of the printed sheet to be certain parts of the sheet is perforated or punched done by folding machines. Incorrect direction of paper flow, for example, lead to a perfect-bound book can not scroll.

For more technical terms: Three Break fold, four- break - fold, wrap, altar or z-fold, plant sites, printed marks ( color bars, registration, investment, and cut marks, bookmark).

Three break - fold

This rebate is also included in Kreuzbruchfalzungen as the two or four- break. The number of folding breaks but is determined by the sheet size, paper characteristics as paper weight or volume by the binding method. To use this type of folding is frequently used in the brochure and book production. This is usually around 16- sided arches. If a plant can not be divide by 16 pages, ½ or ¼ sheets are used.

Displacement

Multiple sheets of paper were folded and trimmed, the pages inside are laterally shorter. The exact value of this - displacement or creep mentioned - the effect is dependent on the number of pages and paper grammage and volume of used paper. When designing a brochure (especially with saddle stitching ), this must be considered.

Most imposition softwares are able to take into account this effect. These pages are continuously engaged by the desired amount to the center of the signature back into the waistband or completely scaled. The engagement is at bund overflow pages - also called deserters - but not always possible, what to take when layouting consideration.

Color guide

The color bar is used the printer for accurate adjustment of the color guide. The individual strips are cut to different presses. They consist mostly of the color fields for the process colors cyan, magenta, yellow and black as well as a different number of special colors and special focus areas. Be measuring these fields with a densitometer or a control stripe reader. The determined values ​​are transmitted to the printing machine and correct the color management in the corresponding color zones. During the contact pressure arc are removed and measured it again and again.

Flattermarken

In collating marks are marks on the back of folded printed sheet. They are used to control the correct order of the arch. In most cases, a black line on the order of 2 × 10 mm is used, which in an adhesive bond in the routing edge - so the back - is located. For example, the brand of the first sheet is 10 mm from the upper edge of the sheet; the mark of the second sheet 20 mm, 30 mm, that of the third, etc.; So always displaced, according to this example, the value of a brand. Looking at the back of the collected sheets, the collating marks form a staircase. If an arc lying in the wrong position, the stairs would be interrupted. This control process is called also collate.

Registration mark

Registration mark, cross or pass short registration refers to a graphical figure, with the fit of the individual colors can be monitored in the overprint. In most cases, this brand consists of a circle and a cross made of thin lines, similar to a cross hair. The Mark is ( if necessary special colors CMYK) positioned in each color exactly in the same place. During the printing process are repeatedly printed sheets with a magnifying glass ( thread count ), now also electronically controlled by optical scanning. This is necessary in order to avoid the so-called misregistration, the inaccurate overprinting single color printing. Misregistration lead to blurring in image and font rendering and color deviations or so-called " speed cameras ".