A press proof is very precise in terms of colour and, due to the edition paper used, is almost identical to the later print. Compared to the classic proof, however, a press proof is usually tens of times more expensive and quickly costs several hundred euros. Moreover, a press proof needs much more time for the production. Therefore, it is hardly relevant today for economic reasons and is only used for very delicate prints with high print runs.
Process colours are the colours that are created in printing when several colours are printed on top of each other (usually using halftone screening).
In four-colour printing, this colour is composed of cyan, magenta, yellow and black. With these four colours a very large number of colours with different tonal values can be printed.
To “proof” means to produce a proof or have a proof produced. “I still need to proof the brochure” is the typical phrase for the word “to proof”.
Proofing thus means to have a colour and legally binding proof produced according to the current ISO 12647-7 standard. The current valid revision of this standard is ISO 12647-7:2016, which regulates the central parameters for “proofing” such as target tolerances and specifications for producing the proof, the job tickets and the test report.
Only when an UGRA/Fogra or, for the American proofing standards, an IDEAlliance media wedge is printed does the proof become a proof, i.e. the proofing process differs from the printing process. This media wedge does not have to be measured, but it is of course helpful for the printing company if it does not have to measure first but can see at first glance that the proof has been produced in colour and legally binding according to the current standard.
A proof (correct: contract proof) is an ISO-certified testing device for the graphic arts industry. A proof simulates the colourfulness of offset or gravure printing in a colour and legally binding manner within the narrow tolerances of ISO 12647-7. Today, it is almost exclusively calculated using a RIP and then produced with inkjet printers on special proof papers.
The proof data is converted into separations, then reassembled into a composite image to correctly simulate overprinting and trapping. The data is then transferred as a newly created composite image to an inkjet printer, usually with more than 8 colours, which prints the data. In addition to the print data, a proof must also carry a UGRA/Fogra media wedge in order to be colour-consistent and legally binding. Thanks to the standardised wedge, the printer is able to check the proof for correctness. Since many printing companies do not have this measuring technique at hand, the proof is often provided directly with a test report that shows the correctness of the measured values of the media wedge directly on the proof.
Earlier methods such as Chromalin etc. are no longer available on the market today.
ISO 12647 defines the term “Validation Print” (ISO 12647-8) in addition to the highest standard of contract proof, “Proof” (ISO 12647-7). The Validation Print is characterized by the fact that although it is less accurate in colour, it can also be produced on laser printers. Compared to the contract proof, however, it accepts much higher colour deviations and is only legally binding after prior consultation. A real “proof”, i.e. a real contract proof according to ISO 12647-7 is currently not only by far the best variant in terms of colour, but also the only legally binding proof.
Further information: https://en.wikipedia.org/wiki/Prepress_proofing
A proof becomes a proof that it is produced according to the specifications of the latest revision of the proofing standard ISO 12467-7 and that it is within the tolerances of this standard. The current revision is ISO 12647-7:2016, which has been tightened even further with this standard and has been supplemented by a certified edition of spot colours such as PANTONE and HKS.
But what makes a certified proof cheap? Well, the low price. Proofs are printed on certified proof papers on very high-quality pigment inkjet printers using mostly expensive proof software and measured with spectrophotometers. So how can you produce cheaply here?
The proof costs, i.e. the costs for a proof, are usually calculated according to the format to be proofed and the quantity of proofs. Whether different motifs or one motif is proofed several times is usually irrelevant. 30 proofs of one page each cost the same as a proof of 30 different pages each, because for the proof shops the RIP time is not decisive for the costs, but rather the ink and paper on which the proofs are printed.
Serious suppliers proof exclusively with original inks and Fora-certified proof papers, which also have a good strength of around 250gr/sqm for picture printing papers, and around 150gr/sqm for uncoated papers. By using non-certified papers of lower grammage and especially by using cheap compatible inks and printing systems, some service providers offer cheap proofs, but these can cause problems due to the inferior materials. Non-certified proofing substrates, for example, have not provided proof of durability in terms of mechanical aging; alternative cheap inks sometimes lead to uncontrollable metamerism effects.
In some cases, printing companies in particular also offer a “proof” that they produce in-house without media wedge evaluation. We personally know a printing company whose “proofing device” has not been recalibrated since 2003. The quality of such ” coloured prints” is perhaps decent, but such a print can of course never reach the precision of a “contract proof” according to “ISO 12647-7:2016”.
In 2016, ISO 12647-7 was updated, and with the appearance of a new standard, i.e. ISO q12647-7:2016, the previous standard is automatically cancelled. However, many suppliers do not keep their software up to date, and therefore produce “proofs” according to “ISO 12647-7”, but not according to the latest version of the standard. These proofs do not conform to the standard, and are therefore not colour and legally binding. For end users and buyers, however, these details are difficult to oversee.
The FOGRA certification helps here: whoever has a current and valid Fogra certification must prove that they have colour and legally binding proofs according to the latest standard. And because the certification is only valid for one year, a new certification, again valid according to current criteria, must be issued after one year at the latest. The companies that save themselves the trouble of obtaining such a certification usually have good reasons for doing so.