What is Slug in Adobe InDesign? An In-Depth Guide

As a professional graphic designer, you know that the devil is in the details. Meticulous attention to every aspect of your designs, from concept to completion, is what separates good design from great. Part of mastering InDesign, the industry-standard layout application, is understanding all its powerful features – even legacy ones that may not be used as often, like the "slug" area.

In this comprehensive guide, we‘ll answer the question "What is slug in InDesign?" in great depth. You‘ll learn the fascinating history behind this printing term, see how it applies in modern design scenarios, and discover best practices for making the most of the slug area in your own layouts. Whether you‘re an InDesign novice or a veteran user, this article will level up your expertise!

The Origins of "Slug" in Printing

The term "slug" actually has a long history in the world of printing, dating back well before the advent of desktop publishing software. In metal typesetting, a slug referred to a single line of text cast as a solid piece of metal, such as lead or zinc. These slugs were assembled to create full pages of text.

Another use of slug in traditional printing was as a term for the title or identifying name of an article or story. This slug would be cast separately and stored for future use or reference by the printer.

When phototypesetting replaced metal type, slug came to refer to the paper tape that was punched with text data to control the typesetting machine. Each story on the tape was still referred to as a slug.

So how did slug make the leap to the modern era of digital publishing? In page layout applications like InDesign, the slug area serves a similar purpose as in traditional printing – it‘s a designated space to hold printer-specific information, instructions, and marks outside the live design area.

What is the Slug Area in InDesign?

In InDesign, the slug is a defined rectangular area that sits outside the bleed area, on the outermost edges of your document. Any content placed in the slug will print, but will then get trimmed off after printing, along with the bleed.

The slug is specifically meant to hold information like printer marks (crop marks, registration marks, color bars), job specs, legal disclaimers, or special finishing instructions. It provides a place to include details the printer needs to see that shouldn‘t be part of the actual design.

Slug can be set up when you first create a new InDesign document, or added to an existing layout via the Document Setup dialog. The size of the slug area is customizable per your printer‘s specifications.

How Often is Slug Used in Modern Design?

With the shift to digital workflows, slug isn‘t used as universally as it once was. According to a 2020 survey of over 500 print designers by InDesignSecrets.com, only 26% said they use the slug area on every print project. 41% use slug occasionally, while a full 33% never use slug at all.

However, certain types of print projects still frequently require slug. For example, packaging designs and dielines often utilize the slug area heavily to convey specific cutting, folding and gluing instructions for the printer.

Additionally, some high-end commercial print shops may request that all jobs include slug, either to streamline their own processes or to have space for internal marks and barcodes. So while not ubiquitous, slug remains an important tool for professional designers to understand and utilize when needed.

Detailed Guidance for Setting Up Slug in InDesign

Now that you grasp the concept of slug, let‘s walk through exactly how to control and configure it in InDesign. Whether you‘re creating a new document or modifying an existing one, it‘s crucial to set up your slug precisely per your print provider‘s guidelines.

Setting Up Slug for a New Document

When you create a new print document in InDesign, you have the opportunity to define your slug area right from the start:

1. Go to File > New > Document to open the New Document dialog box.
2. Click the More Options button to expand the full set of document controls.
3. Locate the Bleed and Slug section and expand it by clicking the triangle next to the title.
4. You‘ll see fields to enter the Top, Bottom, Left and Right slug values. If your printer specifies the same slug on all sides (which is common), click the link icon to the right to bind the fields together.
5. Enter the desired slug offset amounts as decimals or whole numbers. Common slug sizes are .5, .625, .75 or .875 inches, but always defer to your printer.
6. Set your bleed while you‘re here, which typically extends .125 inches beyond the trim on each side. The slug will sit beyond the bleed, on the outer edges of the layout.
7. Click Create to generate your new document with the defined slug and bleed.

Adding Slug to an Existing InDesign File

If you‘ve already started your layout and need to add slug after the fact, InDesign makes it simple:

1. Go to File > Document Setup (or press Ctrl/Cmd+Alt+P)
2. In the Document Setup dialog, locate the Bleed and Slug section and expand it if needed.
3. Enter your desired slug amounts into the Top, Bottom, Left and Right fields. Remember, click the link icon to set the same slug on all sides.
4. Click OK to apply the slug and close the dialog.

InDesign will display the new slug area on the outer edges of your document. You may need to zoom out to see it, or switch to the Normal or Slug view mode via View > Screen Mode.

When and Why to Use Slug – Appropriate Use Cases

So when is it appropriate (or necessary) to utilize the slug in InDesign? Let‘s look at some common use cases:

1. Printer marks – If your print provider requires crop marks, registration marks, color bars, or fold marks, these often get placed in the slug area. InDesign can auto-generate printer marks in the slug when you export to PDF.

2. Dielines and package specs – Designers creating packaging comps or dieline files will make heavy use of the slug to include all the relevant cutting, folding and gluing instructions needed for production. The slug is the perfect place to put this crucial info outside the actual package design.

3. Job information – Some printers may request the job name, due date, designer name, file name, and other identifying details be included in the slug on every page for tracking and archival purposes.

4. Legal requirements – Certain print pieces, like financial documents or sweepstakes mailers, may be legally required to include specific disclaimers or eligibility details. The slug provides an unobtrusive place to put these mandatory elements.

5. Paper stock call-outs – If your piece will be printed on multiple stocks, the slug is an ideal place to indicate where each paper should be used, along with any other substrate specs.

6. Finishing notes – For projects that require special finishing like spot coatings, foil stamping, embossing or unique folds, the slug area can hold explanatory notes for the printer to reference.

In all these scenarios, the key is that the content in the slug is specifically meant for the printer‘s eyes only. Notes meant for clients or internal reviewers should be handled through other channels, like PDF annotations or 3rd party review tools.

Risks and Downsides of Improper Slug Use

Just as proper slug use can enhance your print projects, incorrect use of the slug area can cause major headaches. Some hazards to watch out for:

1. Placing live design elements in slug – Avoid this at all costs! Anything put in the slug will be trimmed away, so never flow your body copy, graphics, images or other essential content there. That‘s a quick way to ruin your final pieces.

2. Using slug for non-print content – Don‘t fall into the trap of treating your slug like a surplus area to stuff anything and everything. Stick to printer-only information to prevent confusion.

3. Omitting slug when required – If your print vendor explicitly asks for specific information in the slug, don‘t neglect to include it. The job may be kicked back to you for correction, delaying the timeline.

4. Slug overflow – Be judicious with what you place in the slug. If crammed too full of content, it can actually create print issues or get cut off if the slug area isn‘t wide enough.

5. Inconsistent or inaccurate slug – Whatever slug details you include, be consistent across every page and double check that the information is correct! Conflicting or erroneous slug is worse than none at all.

Slug vs Bleed – A Detailed Comparison

Since the slug and bleed are adjacent parts of the layout, they often get mixed up by less experienced designers. Let‘s clearly define the differences:

Bleed:

• An extra .125" (or 3mm) margin beyond the trim size of the document, on each side
• Ensures design elements and background colors/images extend fully to the document edge with no white borders after trimming
• Part of the actual design/artwork, should be identical in color and content to the corresponding trim edges
• Gets trimmed away but is considered part of the final piece

Slug:

• A (usually larger) margin that extends beyond the bleed area, often .5" or greater
• Meant to hold information for the printer only, like crop marks, color bars, registration marks, fold lines, etc.
• Not part of the actual design – elements in slug have no relation to the artwork and won‘t be seen in the final trimmed piece
• Gets completely cut off and discarded during finishing

So in the printing process, content in the bleed area prints first and becomes indistinguishable from the design. Then the slug content prints outside that. Finally, the bleed and slug are both trimmed away, with the bleed becoming part of the background while the slug gets removed entirely.

Tips and Best Practices for Utilizing Slug in Your Design Workflow

To wrap up, here are some tips and expert best practices to optimize your use of the slug area in InDesign:

1. Communicate with your printer – Always start by asking your print provider what information they need in the slug, and what dimensions to use. Never assume!

2. Use slug templates – Set up InDesign template files with the proper slug already defined to avoid repetitive setup. Just edit the specific content for each job.

3. Stay organized – Keep slug content neatly arranged and labeled so it‘s easy for the printer to find the information they need. Use concise language and readable fonts.

4. Utilize layers – Place your slug content on a dedicated layer. This makes it easy to hide or remove the slug content if needed, without disturbing your designs.

5. Triple check before exporting – Always carefully review your slug content right before sending files to print. Make sure nothing is cut off and all details are accurate.

6. Consider other options – For simpler jobs, you may be able to skip the slug and just include printer instructions in the filename, or in a separate read-me file. Confer with your printer on their preferred method.

By following these guidelines and best practices, you can harness the power of InDesign‘s slug area to better communicate with your printers and elevate the quality of your print design projects.

Conclusion

We‘ve covered a lot of ground in this deep dive into the slug feature in Adobe InDesign! You now know that slug is a designated area on the outer edges of your document meant to hold printer‘s marks, production specifications, and other non-design details needed to properly produce the final printed piece.

While not required for every print job, proper use of the slug area is an important skill for professional graphic designers. By including the slug details requested by your print provider, you demonstrate your expertise and help ensure your designs translate perfectly from screen to paper.

Just remember, the slug is for printer eyes only! Reserve it for production notes, color bars, registration marks and the like. Never place essential design elements in the slug, or use it in lieu of proper client-facing annotation tools.

If you‘re ever unsure about slug, don‘t hesitate to contact your printer and ask. They‘re the experts on their specific requirements and will appreciate your attention to detail. With open lines of communication and proper slug technique, you‘re well on your way to mastering the art of print design with InDesign!