SWOP Specifications - Relevant to Wide Format printing?

SWOP - "Specifications for Web Offset Publications" was first envisioned in 1974. Those specifications have been amended many times since, but the principle remains the same. they're Specifications for Web Offset Publications. 

The intention is to create a set of standards, that offset presses are set to and certifified as complying with. Artwork prepared for SWOP meets specific criteria, and if output on several certified presses, should lead to similar prints from each system.

SWOP sets standards for viewing conditions (D50), Type Reproduction, Image trapping, Vignettes/shadows, screen rulings, screen angles, and total area coverage. It also sets standards that files should be CMYK only, meet certain resolution requirements. A SWOP certified press will use inks that that meet ISO2846-1 Part1. 

In short - SWOP means printed in a certain way, on a certain product, with certain inks.

That's great if what you want is a consistent result off many presses. That is what SWOP is for. But there is another way to look at this.

In meeting those standards, the training wheels are on. Even if more vibrant ink sets are available, to print to SWOP standards you have to limit your range. In short, colour capabilities are restricted.

Wide Format Digital Print - is SWOP useful?

Wide Format Printers invariably have much larger colour gamuts than the SWOP standard on most papers/media. In other words, you can get more colours from a wide format printer than you can from a SWOP certified Offset Press. When you think about it, that's why wide format printers are often referred to as proofers - you can simulate the output of the offset press on a digital printer because the digital printer can produce everything the offset machine can and more. 

So what does that mean for the artwork designer? 

US WebCoated (SWOP) v2 is the default CMYK working colour space that ships with Adobe Creative Suite. At the time of writing, CS5 was the latest, and it shipped with that space set as the default.

If you create a CMYK artwork, and don't specify a different space, you're in US WebCoated SWOP v2. If you create an RGB artwork, but save to pdf/x1a before you ship to a printer, you've converted to SWOP.

That's fine if you intend to do it. If your artwork is going to print on a SWOP certified press, then you're spot on - great artwork. But there are two main other conditions to consider.

(1) the artwork is to be output in several different ways, one of which is a SWOP certified press.

(2) the artwork is not being output on a SWOP certified press at all

In (1) you have a decision to make. Every output route has it's available colour gamut. Some devices can print more colours than others. If you want every print via every method to match perfectly side by side, you have to limit the larger gamut routes to the gamut of the smallest gamut device. For example, if you were printing posters to SWOP, and banners on a wide format device you could limit the gamut of the wide format device to SWOP. (you could do this by sending SWOP artwork to the digital printer, which is a VERY common scenario.) 

However, you have the option of accepting the limitations of the US Web Coated SWOP v2 space for the offset output, but choosing to use a wider gamut of colours from the wide format device. You'd do this by creating artwork in a larger colour space, eg Adobe RGB 1998. That artwork can go to the wide format printer, and be converted to the smaller SWOP gamut by the offset printer (or converted before you send it if the offset printer demands SWOP artwork.) Now your two prints won't match because your wide format print will use the full colour range of the wide format printer, which is larger than the offset press. This will only be useful in some circumstance. A lot of the time you will need the prints to match, so limiting to SWOP is your only route.

In (2) you don't have the decision to make. If you're only outputting to wide format, you don't have to limit yourself at all. Design in the a large working space. (most use Adobe RGB 98.) You then have the option to make use of the wider colour range available on wide format machines - making your design stand out when next to SWOP limited designs. If you build your artwork in a SWOP colour space such as US Web Coated SWOP v2, then you simply can't specify those colours! 

To conclude: SWOP is useful if you're preparing artwork for SWOP certified offset printers, or where that makes up one element of a multi faceted production that must match. SWOP is fine for wide format printing, but if your artwork is in a SWOP colour space, you are not using the full colour possibilities of the wide format printer. That situation is perfectly fine when it's intentional, but when it's an unfortunate by product of habit and default software settings, it's time to make some changes and get your designs SHOUTING! 

If this article has you thinking about artwork you produce for wide format printing and you'd like to discuss it further, call us on 01702 232500 and we'll do what we can to help you.