What is a press-ready PDF?
PDF stands for Portable Document Format and was created by Adobe Systems primarily for document exchange. Most people will be familiar with the 2D fixed layout when exchanging files over email or downloading information from the web. PDFs are used to encapsulate the complete description of a file by embedding its fonts, images and graphics along with other information such as hyperlinks, etc so that the end user is able to view the file in its correct form without the need to receive any extra files in order for the layout to appear as intended by its creator.
Press ready PDFs are usually the preferred format for commercial lithographic printers when supplying artwork. Press ready PDFs differ from standard PDFs in that they must meet a certain criteria in order for the file to print without problems. Standard PDFs may include colours that may not print correctly or graphics that are fine to view on screen but will print at a very low quality. Each printer will have their own specifications for supplying artwork. However, it is understood that some rules are standard and all press ready PDFs will need to contain the following:
1. Embedded fonts. Embedding fonts into the PDF is necessary for the fonts to render correctly for print. This means that the fonts used in the document, being present on the designer’s machine will be embedded into the PDF. Therefore, the designer does not need to supply any fonts to the printers. If the fonts are not embedded within the PDF, they may appear correct on the designer’s machine as they will be present on that system but when viewed on a computer without the necessary fonts, substitutions are often made and missing fonts are usually replaced with the nearest font available. The Courier typeface has long been used in the printing industry as the default for most font substitutions and alarm bells will usually go off with most designers and printers when they see this font – unless it is being used as part of the design!
2. Bleed. Bleed is crucial to any design in which the pictures and/or colour run to the edge of the page. This is one of the most common errors we see when receiving PDFs that are not correct for print. A press ready PDF will include at least 3mm bleed on each side of the document which will make the final PDF 6mm bigger in size, both in height and width. The bleed is then trimmed away when finishing. For example, an A4 page measuring 210 x 297mm with a solid background would need to be supplied as 216x313mm with the colour extended to the edge of the page. Some programs make it hard to create bleed but it can usually be overcome by making the page size bigger and cutting into it.
3. Correct colours. A press ready PDF will contain the correct colours for print. This will either be cmyk, spot colours or a mixture of both. Press ready PDFs will never contain RGB or web colours as these are only suitable for digital viewing and not for lithographic print. A correct PDF will contain ONLY the colours needed for print. This means the designer will remove any default colours from their swatches palette so that the colours needed for final output is clear. It must be remembered that each colour is a separation and that becomes a plate on press. If a designer has created a 4 colour job plus a 5th spot colour, we would expect to see 5 colours only in the PDF. Any more or less and we will assume there is a problem and the PDF is not be ready for print.
4. Images. Images in a press ready PDF need to be at least 300dpi at the size they will be printed. For example, an A3 poster of one image will need to be 300dpi at A3, not at A4 and scaled up. They also need to be composed of CMYK or spot colours as per above and not made from RGB or web colours otherwise they will more often than not, appear washed out and de-saturated when printed.
5. Overprinting. The designer will need to check all overprinting carefully and make sure that overprint preview is switched on in Acrobat. This will give a guide as to which colours will overprint and which will remain unchanged. If this is not turned on, the file may not print as it appears on screen. Therefore, all overprinting must be correct in a print ready PDF. This is something that is very important for the designer to check as it is not always obvious to the printer, especially in larger files with many pages.
6. Transparencies. Transparencies need to be exported correctly and the safest way we have found is by using 1.4. Pdf’s before this version do not include transparency and will flatten all elements. Our systems and workflow support 1.4 and above. This is quite an in-depth topic which I won’t go into here. However, there is a nice link we have found that may help… http://docs.scribus.net/index.php?lang=en&page=pdflavor
The above points are all necessary and must be included and checked before supplying a press ready PDF. The following list is made up of further criteria that we think all good press ready PDFs should contain:
7. Page Layout. The page layout should be fairly obvious to the printer upon opening the PDF. We would like to see blank pages in the document if they are needed. If the document is perfect bound, we would expect bleed on all edges and a saddle stitched book with bleed on at least all three outside edges. We prefer not to have imposed files and do not like to work with printers pairs. Readers pairs are not really accepted as being in a correct print ready PDF. A complete document of single pages running from the front cover through to the back cover is our preferred format for PDF page layout.
8. Correct folding. If the document is to be folded such as an invitation or leaflet, the folding will need to be checked by the designer before supplying a press ready PDF. Do the pages back up correctly? Does any of the pages appear upside down or does the text run into the folds? etc.
9. Quiet area. The quiet area is often referred to as the area that is usually between 0mm to 5mm from the edge of the page. This applies to borders, text, images and in fact any element that sits too close to the edge. This is not to be confused with bleed. As there is often movement when trimming large quantities of printed material, elements that are within this quiet area are in danger of being trimmed into. As a rule, it is best to avoid this area when designing a document as the safest way of ensuring that this doesn’t happen.
10. File compression. While it is convenient to reduce files down to a manageable size, the designer must consider the final resolution of the print ready pdf. It will need to be at least 300dpi as discussed above. We find that various compressions such as LSW can often cause problems. Therefore, we think it safer to reduce the images separately at a suitable resolution first and then and save them with no compression.
Hopefully this gives a brief explanation of print ready pdf’s and an understanding of why they are so popular in the printing industry. In summary, supplying a press ready PDF can eliminate the need for the designer to supply all of the extra files to the printer and they are convenient and often smaller in size than the original documents. Creating a PDF that the printers can use without the need for loading all of these files onto their system saves a lot of time. It also stops the potential problems of fonts not loading properly and pictures being incorrectly placed. Pdfs are made primarily to be viewed and not amended. This is one of the reasons why PDFs are so popular and can eliminate the need for further proofs.
In short, Press ready PDFs create a consistently simple and uniform workflow between the designer and the printer, enabling a smooth and problem free transition from design through to print. There is a nice little site that we have found at www.prepressx.com/ which explains these points in some more detail.
Giving a press ready PDF to your printer
When a PDF is properly prepared, your printing company will be able to take the file and produce full colour output. The quantity of your print run will most likely determine whether your printer uses a digital or lithographic printing press. You should be aware that there are some differences in the way that you’ll need to present your PDF – related to CMYK separation. It therefore makes sense to speak to your printer in advance of preparing your PDF.
At PrintHouse we have nearly three decades experience in taking PDFs in for printing. We were founded in 1990 and PDFs were introduced in 1993 by the way.
If you have a PDF that needs to be turned into a printed item, contact us today and we’ll be delighted to provide you with advice and a quote. Call on 020 8963 0123 or use the contact form below:
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