Job Planning, Layout and Proofing

From Machine Proofing to Digital Proofing

After the color separations have been produced, the use of a prepress proofing system is suggested. The probability of error is high in color separation work because every original is different and the process is usually performed under time restrictions.

The primary purpose of a color proofing system is to catch errors or mistakes prior to the press run, where corrections would be expensive, mistakes will reduce profits and could prevent potential future work from a customer.

There are two traditional methods of proofing color separations, and a third techniqure that is evolving with the new electronic technologies.

The first traditional method is to proof with a set of inks on the press. The second is to use a photographic or photomechanical proofing system. The photo-mechanical proofing systems are more popular and more economical.

Photo-mechanical proofing systems are categorized into single sheet or laminate color proofing systems and overlay color proofing systems.

The advantage of single sheet or laminate proofing is that the viewing light is reflected from a single surface and light refraction is limited.

A major advantage of overlay proofing is that individual colors, secondaries, and three color overprints, can be examined independently. with the increase of undercolor removal in four color separations, overlay proofing is becoming more important to the press crew that must compare the press sheet to the proof.

The third technigue of pre-press proofing is emerging from electronic pre-press technology. The electronic or digital color proofing systems can be either soft proofing on the visual display terminal, or hard copy proofing using recorders, cameras, or ink jet printers.

Many prepress proofing systems are available. Each of these systems has their own advantages to the industry.

Regardless of which proofing system is selected, some basic requirements should be observed. Basic requirements of a proofing system include:
1 .The proofing system should match the press run or ink capabilities.
2. The proofing system should have consistency in results.
3. The proofing system should have a minimum of operator skills requited.
4. The proofing system should have customer acceptance.
5. The proofing system should be practical for in-plant use (pressroom).
6. The proofing system should selected should work from both negative and positive final films (separations).

Most large color separation houses will use several different systems of prepress proofing. This is done in an effort to give the client a selection or choice.