cromalin proofs

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chromalin proofs are CMYK laminated printing proofs

Cromalin Proofs Definition

Cromalin Proofs are the product of a proofing process. They are used to approve offset CMYK printing before going on press. Cromalin is a proprietary brand name and process created by duPont. The Cromalin Proofs definition means that these are press proofs used to approve a final design in printing. The next step in the printing process would be the press check. Cromalin proofs are one type of proof that is used in printing, and is typically created by a pre-press professional at the printer. In 2002, duPont introduced a lower-cost digital Cromalin proof.

 

How Are Cromalin Proofs Made?

The process of making a Cromalin Proof is a photographic process. This process uses ultraviolet cured high-intensity polymer pigments (toner). After the 4-color negatives for a print job are produced, the prepress lithographer can make a Cromalin proof. First they coat a sheet of gloss white card with a clear photosensitive layer using a heat roller. This photosensitized clear plastic layer is actually made of two parts. Once it is exposed to the image on the first yellow negative using UV, the prepress lithographer peels off the top layer and the substrate beneath is then tacky in the areas where the yellow toner should be applied. Then the sheet is carefully dusted with a powdered yellow polymer toner. The toner adheres to the sticky surface dots.

Then the process is repeated for the other three colors – cyan, magenta and black. this process can take from 45 minutes to an hour. Once all four sheets are exposed and powdered, they are aligned with registration marks and laminated together to form the final Cromalin proof. This is a very close simulation of what a final printed sheet might look like when printed. And it used to get a final sign-off from the designer and their client.

 

What is the Purpose of a Cromalin Proof?

Cromalin proofs are overall useful for confirming correct sizing and position of page elements. It is also used to confirm colors and check the registration of the color plates in CMYK printing. It is also used to check for blemishes and marks on the plates/negatives that will be used to print on press.

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