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A Prepress Guide for CMYK Printing

By May 28, 2024Training Guides5 min read

A Prepress Guide for CMYK Printing

User-friendly guide for designers in preparing prepress artwork

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17 Essential Steps For Graphic Designers

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Creating prepress artwork for lithographic offset printing requires precision and attention to detail to ensure your final product looks perfect. Follow this comprehensive checklist to set up your artwork correctly and avoid common pitfalls. This guide will help designers navigate the prepress process smoothly.


Keep All Text at least 3mm from any edge

Ensure all important text is within safe margins to prevent it from being cut off during trimming.

Steps in Illustrator:
- Use the "Rectangle Tool" to draw a box with a margin of at least 3mm from the edges.
- Position your text inside this box.


Convert All Files to CMYK Colour Mode

RGB colours can cause printing issues. Convert your files to CMYK to ensure accurate colour reproduction.

Steps in Illustrator:
- Go to "File" > "Document Colour Mode" > select "CMYK Colour".
- Check your colours in the "Colour" panel to ensure they are CMYK.


Convert Any Spot Colours to CMYK

Ensure all spot colours are converted to CMYK to avoid unexpected colour shifts.

Steps in Illustrator:
- Open the "Swatches" panel.
- Double-click any spot colour swatch to open the "Swatch Options".
- Change the colour type to "Process Colour" and adjust to CMYK values.


Flatten Lens Effects and Special Effects

Flattening ensures that complex effects print correctly.

Steps in Illustrator:
- Select the object with effects.
- Go to "Object" > "Expand Appearance".
- Repeat as necessary for all objects with effects.


Confirm Type is Embedded or Outlined

Embedding or outlining fonts prevents unexpected font replacements.

Steps in Illustrator:
- Select all text objects.
- Go to "Type" > "Create Outlines".


Check for and Remove Any White Overprint

White overprint can cause hidden elements in your print.

Steps in Illustrator:
- Go to "Window" > "Attributes".
- Select all objects, then check the "Attributes" panel to ensure "Overprint Fill" is unchecked for white elements.


Apply Trapping to Type on Solid Backgrounds

Trapping prevents gaps between colour registration.

Steps in Illustrator:
- Select your text and background.
- Use "Window" > "Pathfinder" > "Add to Shape Area" to merge and create a trap manually if needed.


Include Trim Marks and Fold/Crease Marks

Trim and fold marks guide the trimming and folding process.

Steps in Illustrator:
- Go to "Effect" > "Crop Marks" to add trim marks.
- Draw lines manually with the "Line Segment Tool" for fold/crease marks.


Ensure No Hidden Objects in the Background

Removing hidden objects avoids printing errors.

Steps in Illustrator:
- Use "Select" > "Object" > "All" to highlight all items.
- Check the "Layers" panel for hidden items.
- Use "View" > "Outline" to preview and remove or make visible as needed.


Use Rich Black for Backgrounds

Rich black ensures a deep, solid black colour in prints.

Steps in Illustrator:
- Set your black colour to a mix of 50% Cyan, 50% Magenta, 50% Yellow, and 100% Black in the "Color" panel.


Ensure High-Quality Images

High-quality images prevent pixelation and ensure clarity.

Steps in Illustrator:
- Ensure all images are supplied, and set to at least 300 DPI.
- Go to "File" > "Document Info" > "Linked Images" to check the resolution.


Visually Inspect for Anomalies

A thorough inspection catches any last-minute issues.

Steps in Illustrator:
- Zoom in and visually check your artwork for any anomalies or errors.


Ensure Proper Type Size

Small type can be hard to read or print poorly.

Steps in Illustrator:
- Check and ensure type size is appropriate, especially for text smaller than 6 points.


Flatten Transparent Objects or Layers

Flattening ensures print compatibility and avoids issues.

Steps in Illustrator:

- Go to "Object" > "Flatten Transparency".
- Adjust the settings and click "OK".


Use Crop Marks in Registration Color

Crop marks should be in registration colour to ensure they appear on all separation plates and provide accurate alignment.

Steps in Illustrator:
- When applying crop marks, set their colour to "Registration".
- You can do this by selecting the crop marks and setting the colour in the "Swatches" panel to "Registration Color" (the colour with a small cross icon).


Save Documents as High-Quality PDFs

High-quality PDFs ensure print accuracy while being compatible with all providers.

Steps in Illustrator:
- Go to "File" > "Save As" > choose "Adobe PDF".
- Select "PDF/X-4:2010" or "Press Quality".
- It may be a good idea to ensure fonts are outlined, and also avoid any excessive compression.


Utilise Adobe Acrobat Pro’s Preflight Check

Preflight checks catch any remaining issues.

Steps in Acrobat Pro:
- Open your PDF in Acrobat Pro.
- Go to "Print Production" > "Preflight".
- Run the "Digital Printing" or relevant preflight profile to check for errors.


By following this comprehensive checklist with detailed guidelines, you’ll ensure that your prepress artwork is set up correctly for lithographic offset printing. Proper preparation can save time, reduce errors, and ensure a high-quality print outcome. Happy designing!

John Kokkinos

Born and raised in Melbourne, John's roots in the packaging and printing industry run deep, shaped by a family legacy of craftsmanship and innovation. With over three decades of dedicated experience, he has honed his expertise in print packaging, demonstrating exceptional skill in managing production lines with finesse. John's professional journey has led him to China, where he spent more than 20 years spearheading the establishment and optimisation of packaging facilities. Renowned for his leadership and industry acumen, he has earned a reputation as a trusted leader and innovator in the field.