How to Create a White Underbase in Adobe Illustrator  |

And we're back to Screen Printing Art 101! If you watched the video about making color separations in Adobe Illustrator, you'll want to watch our latest video as well. Screen Printing Expert Colin Huggins walks you through the process of creating the white underbase in Illustrator.

Huggins uses a three color design in the tutorial. The design has big open areas as well as tiny, intricate designs. Having the varying level of detail will help demonstrate the best way to create the underbase, no matter what art you're working with.

person working on design in adobe illustrator


  • Swatches for spot colors.
  • Layers for each color.
  • Strokes for trapping and choking.
  • Pathfinder for looking closely at layers.

Of course, there are always keyboard shortcuts that are super helpful to know when making designs. Here are a few you should keep in your back pocket:

  • CRTL/COMMAND V = Paste
  • CRTL/COMMAND F = Paste in Front
  • CRTL/COMMAND B = Paste in Back
  • CRTL/COMMAND 2 = Lock
  • CRTL/COMMAND G = Group

Insider's Note: Having a large monitor is extremely helpful! You'll have more space in the program to play around while still having easy access to all your tools.


Printing the wrong design or placing the design incorrectly is a costly mistake. To avoid this issue, Colin suggests putting as much information about the order on the film. Details like the date, where on the garment the design will be printed, mesh counts, colors, etc. It makes it easier for the printer and helps keep the process moving smoothly.

illustrator screen focusing on registration marks

When it comes to registration marks, it's up to you to decide what'll help you register perfectly and easily on press. Colin likes using 1 pt thickness for his registration marks because it helps him see when he's off quickly. Using 2 or 3 pt thickness makes it less obvious when registration is off.


Before making the white base, you need to clearly separate each color. With Colin's design, there are areas of it that need to be filled. Parts of the design overlap with other aspects, so those areas need to be merged in order for the white base to be made correctly. Here are the steps to follow to clearly define each color:

  1. Select and copy the whole design/reg marks/info.
  2. Turn off Working Layer.
  3. Enter the Colors and Separations Layer.
  4. CMD/CRTL F to paste the design in front.
  5. Lock black background.
  6. Select the design.
  7. Any strokes or editable texts needs to be converted to solid fill. Go to the Menu, click Object, then click Expand. A popup menu will appear. Make sure Object and Fill are both checked. Click OK.
  8. For parts of the design that overlap, you'll have to do this step. Select the whole design, go to Pathfinder and click Divide. The parts that overlap will show up as individual pieces. Select the aspects that you want to merge with the top layer.  Go up to Select and click Same Fill Color. Go to Pathfinder and click Unite. It'll become one with the part it was overlapping with. Do the same for all overlapping parts of the design.
  9. Your colors are ready to go!


Time to make the underbase. Let's look at the steps Colin takes to achieve this goal:

  1. Select the whole design and copy it.
  2. Go to the White Base Layer and CMD F (paste to front) the design.
  3. Select the whole design (not including the info and reg marks).
  4. Go to Swatches and apply your white. 

person's design in illustrator

As you see, Colin ran into a little issue. One aspect of the design did not apply to the white base. The program recognizes this area as an empty space; therefore, it noted the area as zero fill, zero stroke. That's actually a helpful hint for you. All you need to do is go to the menu on the left of your screen, select the color swatches that say Zero Fill and Zero Stroke. Go to Select, hover the cursor over Same, click Fill & Stroke. Select the layer and delete it.


When printing white underbases, printers do not want the white base to show on the print. To make sure that it doesn't happen, the white base needs to be slightly smaller than the design so that the colors can cover the edge of the white base. What you'll need to do is choke the white base. To choke the base, make the stroke not as thick as the strokes on the colors. If the strokes on the colors are one point, try 0.5 for the underbase.

Congrats, you now know how to make the perfect white underbase! I know, that was a lot of information. If you have any questions, please don't hesitate to reach out to us. We're here to help. Either email us at or call at 1-800-314-6390. 

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