Cromalin is a proofing production method, developed by DuPont in the 70s. The production of Cromalin proofs are done by layers of successive exposures on film which are then laminated onto special paper.
Today Cromalin are no longer important in the production of proofs. It wasi completely replaced by cheaper and faster digital Inkjet proofing.
A Digital Proof (Contract Proof) is an ISO certified test equipment for the graphics industry. A digital proof simulates the colour of offset printing or gravure printing colour accurate binding within the tight tolerances of ISO 12647-7. Today, a digital proof is processed via a RIP and then produced with pigment inkjet printers on special proofing papers.
The proof data is converted to colour separations, then reassembled into a composite image to simulate overprinting and trapping correctly. The data is then passed as a composite image to a usually more than 8-colour inkjet printer, which prints the data. In addition to the proof data, a digital proof must carry a Mediawedge by UGRA / FOGRA or IDEAlliance to be legally binding. Thanks to the standardized mediawedge, the print shop is able to check the proof for correctness. Since many printers don’t have the neccessary metrology at hand, digital proofs are often directly provided with a test report, which documents the accuracy of the measured values of the media wedge directly on the proof.
Older proofing methods as chromalin or Kodak Approval etc. are today hardly any more found in the market.
In addition to the term “digital proof” even terms like colour proofing, proofing or online proofing are common.
In the ISO 12647 “Contact Proofs” (ISO 12647-7) are the highest standard of proofs, but the term “Validation Prints” (ISO 12647-8) is also defined. A “Validation Print” is distinguished in that it is less accurate in colour, but therefore can also be produced on laser printers. Compared to the contract proof, a Validation Print has higher colour variations and is NOT automatically legally binding – only after prior consultation. A real “proof”, ie a real contract proof according to ISO 12647-7 is currently not only the most colour accurate and best option, but also the only legally binding proof.