Process Work

[dkelley]

Can anyone explain the process for doing process work
Such as color matching the printed sample. What do you match it to if there is no previous run (new job).

[mattbeals]

Approved contract proof for press guidance. Or, an in house standard of one variety or another. A lot of shops will run to standard densities and call it good.

[gordo]

Can anyone explain the process for doing process work
Such as color matching the printed sample. What do you match it to if there is no previous run (new job).

The presswork is aligned with (matched to) whatever proof has been agreed to by the printshop and customer. If there is no proof supplied (yikes) then the presswork is run to an industry specified print characteristic (e.g. ISO 12647-2) or the shop standard for solid ink density and you get what you get or whatever the press operator thinks is correct.

best, gordo

[jotterpinky]

Does the specification specify what the densities should be, e.g. a 50% halftone creates a 65% dot on the sheet? or is the standard density equal, e.g. a 50% dot in the artwork equates to a 50% dot on the finished sheet?

[gordo]

Does the specification specify what the densities should be, e.g. a 50% halftone creates a 65% dot on the sheet? or is the standard density equal, e.g. a 50% dot in the artwork equates to a 50% dot on the finished sheet?

There is standard ink density for the solids and there is dot gain/TVI.

The historical TVI values for a #1 paper are K 22%, C 20%, M 20% and Y 18%

Presswork is not normally linear - i.e. a 50% request in the art, or a 50% dot in the artwork, should not result in a 50% dot on the finished sheet.

best, gordo

[David Milisock]

In a shop that has their ducks in a row. The plate setter/press combination, is linerized and calibrated to the shop paper establishing ink densities based on the ink manufacturers recomendations and the paper. Usually an instruction set for coated and uncoated paper for each press is created.

Then the pressman will run to pre-established ink densities. It's really just that simple.

Some people want to calibrate the plate setter/press process to a standard such SWOP or Gracol using ICC profiles, others use a postscript color management, depending on the caliber of the technician either of these process can be dubious. Unfortunately in some cases even manufacturers tcechnicians can be suspect.

With an ICC system the color is converted to the ICC standard used for the press with an ICC profile controlled system and can allow the use of NON-CMYK color models in the RIP process with REASONABLE conversions from non-CMYK models to CMYK.

With a postscript color managed process the same thing happens and while the CMYK gamut of the press may be expanded slightly ONLY CMYK source color data can be processed properly

Color management is in the hands of the file creator as the press system once calibrated simply requires maintenance.

[gordo]

In a shop that has their ducks in a row. The plate setter/press combination, is linerized and calibrated to the shop paper establishing ink densities based on the ink manufacturers recomendations and the paper.

IMHO, in 99% of the cases there is no need to "linearize" the plates before applying a tone reproduction curve (it's a redundant step). Generally the SIDs come first since they are a print industry specification and are integral to the mechanics of the process. The ink vendor will then help the printer select the ink series that performs best at that spec.

best, gordo

[David Milisock]

IMHO, in 99% of the cases there is no need to "linearize" the plates before applying a tone reproduction curve (it's a redundant step). Generally the SIDs come first since they are a print industry specification and are integral to the mechanics of the process. The ink vendor will then help the printer select the ink series that performs best at that spec.

best, gordo

Maybe you and I are on the same page but reading the book in a different lanquage. What I mean by linearize the plate is running the plate setter base calibration process. This assures that the plate setter is responding to the input signal properly by verifying the plate output against a known target.

[TerryWyse]

What I mean by linearize the plate is running the plate setter base calibration process. This assures that the plate setter is responding to the input signal properly by verifying the plate output against a known target.

How would one know that the "plate setter is responding to the input signal properly" and what is "known target"? Seems rather ambiguous...can you be more specific?

Terry

[David Milisock]

How would one know that the "plate setter is responding to the input signal properly" and what is "known target"? Seems rather ambiguous...can you be more specific?

Terry

The last Heidelberg device I worked with had a target file you imaged on the plate and read it with a densitometer. How else would you know if the plate setter is operating properly?