Select File > Document Color Mode > CMYK Color.
Last updated on
Oct 27, 2026
Create overlaps between adjacent CMYK colors to prevent white gaps caused by printing registration errors.
During commercial printing, slight misalignment can create visible white gaps between adjacent CMYK colors. Trapping compensates for this misalignment by creating small color overlaps. Illustrator automatically determines whether to apply a spread or choke based on color values:
- Spread: A lighter object overlaps a darker background, appearing to expand into the background
- Choke: A lighter background overlaps a darker object, making the object appear reduced
Before you begin
- Convert your document to CMYK Color mode
- Ensure adjacent objects use different colors
- Confirm recommended trap thickness with your print service provider
Practice trapping techniques directly in Illustrator to see how spreads and chokes work with your artwork.
Apply automated trapping
Use this approach for simple objects that need automated trapping.
Select the adjacent objects you want to trap.
Select either:
- Window > Pathfinder > Trap (applies permanent trap)
- Effect > Pathfinder > Trap (applies editable trap effect)
Configure the trap settings:
- Thickness: Enter the trap width recommended by your print service provider (trap value equals half the stroke width)
- Height/Width: Enter 100% for equal trapping, or increase above 100% for thicker horizontal traps
- Tint Reduction: Enter a percentage to reduce the lighter trap color (verify with your print service provider)
- Traps With Process Color: Convert spot-color traps to process colors
- Reverse Traps: Enable to trap darker colors into lighter colors (does not work with rich black containing additional CMY inks)
- Precision: Enter a higher value to increase path calculation accuracy (available only when applying Trap as an effect). Higher values improve accuracy but require more processing time
- Remove Redundant Points: Remove unnecessary anchor points from the resulting paths (available only when applying Trap as an effect). This simplifies the resulting paths
Select OK.
Illustrator identifies the lighter-colored artwork and overprints it onto the darker artwork, creating the overlap area.
Tip
Apply trapping as an effect to edit the trap settings later.
Create a manual trap
Use this approach for complex artwork that needs precise control or when automated trapping doesn't work.
Select the topmost object that needs trapping.
In the Stroke box in the Tools panel or Color panel, set the stroke color:
- Match the fill color to create a spread
- Match the background color to create a choke
Select Window > Stroke and enter a stroke weight between 0.01 and 1000 points (your trap value equals half this stroke width).
Select Window > Attributes and enable Overprint Stroke.
Trap a line
Select the line that needs trapping.
In the Stroke box in the Tools panel or Color panel, assign a white stroke color.
In the Stroke panel, enter the desired line weight.
Select Edit > Copy, then select Edit > Paste in Front.
In the Stroke box, assign the desired color to the copied line.
In the Stroke panel, assign a line weight wider than the bottom line.
Select Window > Attributes and enable Overprint Stroke for the top line.
The white stroke creates a knockout while the overprinted colored stroke creates the trap.
Trap part of an object
Use this approach to trap specific edges rather than the entire perimeter, such as drop shadows.
Use the Pen tool to draw a line along edges that need trapping, or use the Direct Selection tool to select and copy existing edges, then select Edit > Paste In Front.
In the Stroke box in the Tools panel or Color panel, assign stroke color values:
- Match the fill color to create a spread
- Match the background color to create a choke
Select Window > Attributes and enable Overprint Stroke.
Trapping best practices
Apply these guidelines when preparing trapped artwork:
- Common process colors: Objects sharing a common process color create automatic traps and don't need additional trapping.
- Small black text: Use overprinting instead of trapping for small black text on colored backgrounds.
- Similar color densities: When objects have similar densities, use the Reverse Traps option if results are unsatisfactory.
- Print service provider guidance: Confirm trap thickness and tint values with your print service provider before finalizing artwork.
Learn more about Pathfinder effects and the effects overview to understand related techniques for combining objects.
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