December 19, 2011 Leave a comment
Why converting spot colour to process on process artwork is not such a good idea.
Ever had a supplier make contact to say that there are spot colours in the artwork supplied, and wondered “Why don’t they just convert it and leave me alone? Why are you bothering me with such a simple thing?”
1) Possible breakdown in communication
For the art department of the supplier, this will normally be the first time that they have seen the artwork and be totally unaware of its history or construction. All the art department will normally be concerned with is that the details on the docket match the artwork, and that the artwork meets the mechanical specifications for the press, such as correct colours, bleeds, page size, etc.
For a prepress operator, observing a spot colour in addition to process artwork raises red flags such as:
- Is the artwork actually meant to be CMYK+spot?
- Is the artwork meant to be all spot colour?
Similarly, if a prepress operator receives artwork with instructions that the artwork is to print in Pantone Red 032 for example, but the file is prepared in Pantone Warm Red, the prepress operator will ask the question: is the colour being printed on the docket correct, or is the ink in the customer’s artwork correct? This is not uncommon problem in a printing business and is a great way of delaying proofs and creating confusion.
2) How the conversion is done
“Converting” a spot colour all depends on how the conversion to process is done. Take for example the color Pantone Red 032. Depending on which application made the PDF, the colour can appear with several breakdowns:
- Adobe InDesign 5.0 (Pantone Solid Coated Library) – C0 M90 Y86 K0
- Adobe InDesign 5.0 (Pantone Color Bridge Library) – C0 M90 Y60 K0
- Quark Xpress 8.0 – Solid Coated Library OR Color Bridge (using the CMYK output) – C0 M90 Y60 K0
- Quark Xpress 8.0 (using the CMYK and spot/As Is methods) – LAB colour
In addition to this, the printer’s RIP also has the ability to convert spot colours to process in a PDF based on the alternate value within the PDF, or a value based on a spot-to-LAB-to-CMYK conversion.
Furthermore, a customer’s corporate stylesheet may have several colours of a logo depending on the circumstance that the artwork is being used, such as:
- if appearing in newsprint in process, use this breakdown;
- if appearing on glossy stock in process, use this breakdown;
- if appearing in newsprint in spot, use this spot colour;
- if appearing on glossy stock in spot, use this spot colour;
3) If the PDF has transparencies, drop-shadows or the like.
If the PDF has been made to Acrobat 4 compatibility (1.3) and features drop shadows or any effects above a spot colour which was flattened once the PDF was made, then a spot to process conversion may not even be possible. Areas which were flattened will become white, as demonstrated in the illustration below.
4) The client’s expectations of spot v process
Some spot colours such as metallics, fluoroescences, pastels etc convert terribly to process, regardless of which method to convert them was used. If the client has chosen spot colours from a swatch book with no process equivalent next to the swatches, and expects these colours to reproduce out of process colours and look identical to the swatch book, then they are setting themselves up for failure.
Some swatch books (such as Pantone Color Bridge) does display its swatches with the spot colour on the left and how it appears converted to process on the right.
The bottom line?
If artwork is to print process, prepare the artwork using process colours only. If the artwork is to print in spot colours, make sure that the spot colours in the document are going to be the same spot colours going to press. If your client has supplied you spot colour artwork which should be process, ask them to supply process artwork. If they complain and ask why, point them to this article.