Underbase Effect

Ryan Blake

Updated August 28, 2024 12:37

The underbase effect is used to create a "primer" coat of base color that the actual image will be printed on top of.

A solid underbase is generally used with vector objects and text. It consists of a solid coat of a single spot color, typically white, that follows the contour of the objects above it. The ink is always at 100% coverage. A solid underbase can be the same size as the objects above it, choked down to fit inside the object margins, or bled to extend outside the margins.
A variable underbase is used with bitmaps and gradients. The density of the underbase varies to match the image above. This allows the color of the media to show through behind a transparent area (a picture, for instance).


Solid Underbase	Original Bitmap	Variable Underbase

After creating an underbase, the underbase and associated objects are joined together into a compound object. These make use the Underbase Spot Color. This spot color is device dependent, but the vast majority of devices that support underbases use it. If you use a different color for an underbase, it MUST be a Spot Color.

Creating a Solid Underbase

Select the desired objects.
From the Effects menu, point to Underbase and select Solid Underbase.
- The Underbase tab appears in DesignCentral.

In DesignCentral, select either Choke or Bleed .
Set the size of the Choke or Bleed in the Choke Distance field .
Check With holes to make holes in the underbase beneath any holes in the selected objects above.
Select the color of the underbase from the dropdown list.
Click Apply.

Creating a Variable Underbase

A variable underbase will still use the same spot color, but it will change the saturation of the ink dependent on the parent bitmap image.

Select the desired objects.
From the Effects menu, point to Underbase and select Variable Underbase.
- The Variable Underbase tab appears in DesignCentral.

Set the size of the choke in the Choke Distance field.
Select a Resolution from the dropdown list that the underbase will be applied at.
Select the color of the underbase from the dropdown list.
Click Apply.

Making a Vector Object into an Underbase

Select the desired object.
From the Arrange menu, point to Underbase and select Make Underbase.
Select the color of the underbase from the dropdown list and click OK.

Separating an Underbase from the Objects It Was Based on

To make the underbase into a separate object and the objects it was based on into normal objects again:

Select the compound object containing the object and its underbase.
From the Effect menu, select Separate Underbase.
Alternatively, right click the object and select Separate Underbase

Removing an Underbase

Select the compound object containing the object and its underbase.
From the Effects menu, select Clear Underbase.
Alternatively, right click the object and select Clear Underbase

Releasing an Underbase Back to a Vector Object

Select the objects.
From the Arrange menu, point to Underbase and select Release Underbase. This will create the object as a normal vector object again.