Colour space
Files intended to print in four-colour process should be supplied in the DeviceCMYK colour space, and contain only cyan, magenta, yellow, and black. Any objects in RGB, calibrated RGB or LAB must be converted before being imported into your layout application.
Total Area Coverage (TAC)
Combined colour values should not exceed 300 per cent. This may be required to be lower depending on the paper being printed on. This TAC applies to pictures printed in colour - 300 per cent in the darkest areas with a maximum black of 80 per cent.
Image specification
Resolution and size
Colour and greyscale continuous-tone images should be saved at 300dpi at a print size relevant to its final size on the page. Bitmap images (linework) should be saved at at least 1200dpi and preferably 2400dpi. Resolutions lower than this or images smaller than the final size on the page will lead to a loss of quality.
Format and Compression
Ideally images should be saved as TIFFs, but JPEG compression can be used to reduce file size. I do not recommend the use of RAW files from digital cameras or PhotoShop .psd files as results can be unpredictable if not properly handled.
JPEG compression is a "lossy" format where pixel information is thrown away to reduce file size. Algorithms rebuild the discarded data when the file is decompressed. LZW compression within the TIFF format is a lossless method, replacing repeating code with a tag which is replaced when the file is decompressed.
Vector graphics
Files originated in vector-based illustration software such as Adobe Illustrator should have all fonts embedded or outlined. The colour space should be CMYK and all transparency must be flattened.
Placing graphics
When you place pictures in your layout application allow a "safety margin" between the edge of the picture box and any part of the image that is not meant to appear. This will avoid "rebates", particularly noticeable when you place keylines around your images.
Fonts
Do not style fonts bold and/or italic using the styling buttons in your layout application. Always select the styled version of the font from the font list. If this is not possible, remember that not all fonts have bold and italic versions.Your screen does not recognise this and will display them regardless of whether italic or bold printer fonts exist (common examples are symbol fonts such as Zapf Dingbats or Symbol, for which there are no italic or bold printer fonts). With no associated printer font, a styled screen font will output unstyled, as the default font or not at all. Do not trust your screen - always check that Printer fonts are available before styling bold and/or italic
Outline and shadow text created by style menus should be avoided. Most desktop printers will not successfully show the final printed result, and you may get unexpected or undesirable results.
Fine lettering
Thin lines, rules, medium and small type sizes should be reproduced in a single colour only wherever possible.
Do not use rules defined as "Hairline" in your DTP application. Desktop printers and similar devices will not give an accurate representation of a hairline rule on your proofs.
Keep to a minimum rule weight of 0.25pt for a solid single colour.
Reversed out lettering
Reversed out lettering, or knocked-out type, should be out of a minimum of colours. Type or objects smaller than 10pt in size should ideally be reversed out of one colour only. Small letters reversed out of multiple colours - particularly fonts with fine serifs - will show colour in white type areas even with the slightest mis-registration on press. Check to ensure that reversed-out lettering does not become illegible due to the text's background.
Tints and backgrounds
If you wish to reproduce a large solid black background I would recommend that the black prints at 100 per cent, along with a 60 per cent cyan tint to provide more density. This is often referred to as a "shiner", and produces what is sometimes called a "rich black".
The inclusion of a common colour background or strap heading across several pages of a feature or sections of a magazine can draw attention to the natural minor variations in colour balance that occur across a press/presses and during a press run. This can be minimised by creating these common colours out of as few process colours as possible. Give careful consideration to the use of one, or perhaps two colours to produce the common colour. Such a colour will enable a more consistent reproduction than the same object defined using all four process colours. However, certain two-colour combinations can also be prone to unattractive colour shifts - particularly when both colour values are midtones. Two-colour combinations where one colour is considerably higher than the other prove more stable, producing a more consistent, balanced result.
To assure accurate reproduction on press it is advisable to supply a colour swatch or contract-colour proof.
Black overprint
100% black elements will automatically overprint other colours. This prevents normal black text knocking "holes" in tints. Therefore, it is important that larger 100% black page elements, such as boxes or very large point size text, do not have variations in colour beneath them. These will show through in the printed page. Alternatively a "shiner" (see above) can be used to produce a heavier, more consistent solid.
Trims and Bleeds
All page content that runs to the edge of the page must extend off the page by a minimum distance of 3 mm. This minimum distance is referred to as bleed. If bleed is not applied there is a risk of an unsightly white area appearing at the bleed edge.
Elements that do not bleed should be a minimum distance of 5 mm from the edge of the page. This is referred to as the margin. Elements closer to the edge than this standard risk being trimmed off during the finishing process.
Do not attempt to place text sitting exactly on the trim - you will almost certainly be disappointed with the finished trimmed result.
Consideration should be given the the binding style when setting the margins.
For perfect-bound titles consideration should be given for the area in the backs lost in the spine glueing.
For wire-stitched titles remember that larger paginations cause "bulking" resulting in the centre pages of the magazine being considerably shorter in width than the pages at the front and back. The uneven fore-edge is trimmed away after it is stitched. You may wish to allow a larger fore-edge margin in such cases or a larger margin in the backs to allow for "feathering" at the imposition stage. Check with your Production Controller at Headley Brothers for advice on how to proceed.
Particular attention must be paid to the covers of perfect-bound magazines. The cover is glued along the spine and attached to the first and last page of the contents and can lose an area of around 6 mm in the "hinge". Check the Downloads Page for the PDF "DPS For Covers Template" that will guide you in dealing with this.
Elements across spreads
Accurate alignment of elements that go across a spread cannot be guaranteed. Items that can look bad across spreads on a final printed result are: rules; tint edges (especially diagonals); text and lineart. If it is necessary to run a line of text across a spread make sure the spine falls between words.
This is even more evident in perfect-bound titles which cannot be opened out flat. There is always a certain amount of the page in the backs that cannot be seen. To overcome this, pages which cross a spread should be "thrown out". Check with your Production Controller at Headley Brothers for advice on how this is achieved.
Ink Rubbing
Ink can be transferred through abrasive contact on press and bindery handling systems during the manufacturing process. Matt and silk/satin papers are particularly susceptible to ink rubbing. Consideration can be given to this at the design stage. Where possible avoid facing pages of heavy ink coverage against white, unprinted pages.
Where possible avoid designs where the outside front cover is heavily inked and the outside back cover has large areas of white space or vice versa.
If this is unavoidable, consider a seal, which can sometimes prevent marking.
Web growth
Paper has a tendency to expand as it absorbs moisture and shrink when it loses moisture. In the heatset web offset process heat is applied to the paper in order to flash off solvent and dry the ink. After heating the paper is cooled, and a layer of silicone emulsion is applied to "recondition" it. The heating of the paper removes a percentage of the moisture content which cannot be replaced in the printing process. The width of the web will have reduced by several millimetres when it leaves the press, which results in about one millimetre of shrinkage per page.
In sheetfed printing the opposite occurs. Paper takes up water in the printing process and may stretch due to water absorption.
When sheetfed covers are bound with web offset sections, the covers are trimmed flush with the inner sections. After the trimming the covers release moisture into the air and the web offset sections absorb moisture from the air. The covers may shrink slightly and the web sections will grow and hence show a difference in size. Since the industry-accepted best-practice is to run paper grain parallel to the spine, web growth beyond the sheetfed cover will normally be evident on the fore-edge.
This effect is common within the printing industry and is most often seen when sheetfed covers are bound with web offset sections.
It may be possible to minimise the impact of this effect by careful design of the cover and page one of the content. Speak to your Production Controller at Headley Brothers for advice.