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Preparing Artwork for Screen Printing in Adobe Illustrator

Getting t-shirts printed is an ideal way to promote your business, organization or event. They are a promotional item that people can actually use, and they have the added bonus of being an advertisement for you. In this post, Adobe Illustrator will be used to create a three-color screen print using a fictional company logo, and have it set up to allow a screen printer to easily print the color separations that create the separate screens for each color print. [Links checked February/15/2017]

Although some printers prefer to create their own separations, it’s always good to understand the process. Be sure to communicate with your printer as they will specify their requirements, and will often give you tips for avoiding potential issues in the process.

Further Reading on SmashingMag: Link

Printing Techniques Link

As the t-shirt is going to be printed in three colors, we have to create separate artwork for each layer of color. Each of these layers interact with each other to form a complete image.

Examples of Trap, Knockout and Overprint
Examples of Trap, Knockout and Overprint

There are three artwork techniques commonly used for this type of printing: Trap, Knockout and Overprint. The Trap technique is when the bottom color “bleeds” under the top color, ensuring no gaps are left from inaccurate printing of the second color (when the so-called “registration” between the colors is “off”).

Screen printing is not always an exact printing technique, especially when printing onto fabric surfaces; for this reason the Knockout technique is rarely used, as it relies on printing a color precisely in a gap left on the bottom color. The third technique, Overprint, is the easiest to achieve as the top color prints directly on top of the bottom color; often this produces a new color, as the top ink color is not always opaque.

Preparing Your Artwork File Link

1. Create Layers for Each Color Link

The most reliable way to produce artwork for screen printing is to manually prepare it in Adobe Illustrator. Each of the three colors is going to form a separate artwork in a separate layer, using elements from the main image for each color. Using Layers does not affect how your artwork is output by your screen printer; it just makes it easier for you to work on.

Opening the vector artwork in Illustrator presents the graphic in Layer 1. Select the drop-down menu in the Layers window and select Duplicate Layer twice, to produce three layers of the same graphic; name the three layers after their respective colors, as this will help prevent confusion later on. Ensure the order of the colors is correct: the bottom layer is White; the next color layer is Orange; and the top layer is the Dark Red, which will be printed last, on top of the other colors.

Layers being created and renamed
Layers being created and renamed

2. Create a Temporary Background Color Layer Link

At this stage — because the artwork is being prepared to be printed on a dark t-shirt — create a fourth layer for a temporary background color and name it Temporary Background. A rectangle is drawn the full size of the art board, and given a dark color; this layer will be removed later in the process. Drag the layer to the bottom of the layers, and Lock it. Each color of your artwork produces a separate screen, and the order in which the colors are printed is usually from the lightest to the darkest color.

A Temporary Background layer is created
A Temporary Background layer is created

3. Remove Excess Objects From the Layer Link

The first layer to be worked on, is the bottom White layer. Hide the Orange and Dark Red layers by clicking the Eye icon next to their layers, and make sure the White layer is selected in the Layers window by clicking on its name. As the artwork layer was duplicated in full, all the objects of the graphic are on this layer; some objects must be removed, leaving the shapes that form the white outline of the rocket, the text, and the orange fan shapes used in the background.

4. Outline All Strokes Link

The rocket outline is a solid shape so no further work is needed on the rocket, but the white outline of the text is a thick stroke applied to the text shapes; working with strokes can be unpredictable, so it’s best to create outlines from the stroke by selecting the text and choosing Object ? Path ? Outline Stroke. This ensures consistency if the artwork needs to be resized (Strokes can often be pushed out of proportion when resized with the Scale tool).

Outline Stroke on text objects
Outline Stroke on text objects

5. Create and Apply a Custom Spot Color Link

Select all the objects in this layer and apply a light color to each of them. Avoid using absolute white, as you won’t be able to see the objects when checking Separations later. Apply a color of 20% Yellow to the objects and then, in the Swatches window, select New Swatch from the drop-down menu. Name the swatch “White base” and choose Spot Color from the Color Type menu. Even though it’s set to 20% yellow, it will output as a solid color, titled “White base.”

Creating a new Spot Color Swatch
Creating a new Spot Color Swatch

The swatch now will be in the Swatches window and there will be a dot in the corner to denote a Spot color. The Spot color should be applied to all the objects in the White layer.

Spot color in the Swatches window. Note dot in corner of selected=
Spot color in the Swatches window; note the dot in the corner of the selected swatch

6. Manually Creating Trap Link

Hide the White layer and select the Orange layer. Remove any objects that are not relevant to this color layer, such as the white background objects and the dark red objects. The remaining objects are going to be printed in orange underneath the dark red. Due to the inaccurate nature of screen printing, you can’t simply knock out the shape of the orange elements from the top red color and precisely print over the orange; you have to create Trap between the two colors, to allow for slight “wobbles” in color registration.

Potential mis-registration of two colours, seen between orange and dark red
Potential mis-registration of two colours, seen between orange and dark red

Select an Orange object and choose Object ? Path ? Offset Path. Offset the path by 1 mm to make the object larger in shape. Oftentimes printers specify how much Trap they require, similar to how they might specify Bleed. On this artwork, the white background outlines the color objects, but if you wanted the white to be printed directly behind the colors, without a white outline, you could offset the path of the White objects by a minus figure (for example -1mm).

Left: Before offsetting path by 1mm; Right: After offsetting path to create Trap
Left: Before offsetting path by 1mm. Right: After offsetting path to create Trap

7. Deciding on a Spot Color Link

Once Trap is created for all the orange objects, select all the objects and create a Spot color from the Swatches menu. If you are specifying a Pantone color, name the Spot color with the Pantone Matching System (PMS) reference; otherwise, name it descriptively, in this case, Orange.

Bear in mind that it is often the case that printers have inks that they keep in stock and you could save some cost by using an indefinite “orange” rather than specifying a Pantone color, such as Pantone 179. Additional charges can be placed on inks that have to be bought or mixed for a specific project (especially with smaller print quantities). Talk to your printer and see what your options are, as they might supply you with ink color samples to choose from. Samples are definitely worth paying for; they give you a much better idea of color than swatches do.

Pantone Colors can be found under Window-> Swatch Libraries-> Color Books
Pantone Colors can be found under Window ? Swatch Libraries ? Color Books

8. Knocking Out for the Trap Below Link

Once the Orange Spot color is applied to the Orange layer, hide the Orange layer and show the top layer, the Dark Red layer. Again, remove unneeded objects such as the white background elements, but leave the Orange highlight objects.

Artwork with White base color removed
Artwork with white base color removed

For each object with an Orange highlight, use the Pathfinder tools (Window ? Pathfinder) to Exclude the highlight color, effectively creating a void in the object shapes. This is Knockout; but as we created Trap on the Orange layer objects, we won’t get any registration issues. When using the Exclude tool, the object takes the color of the top object which is excluded. Change the color back to the original Dark Red using the Eyedropper tool on one of the other other objects.

The Exclude tool (circled in green) is excellent for removing shapes from within objects
The Exclude tool (circled in green) is excellent for removing shapes from within objects

If the artwork was not being split into layers, the Knockout and Trap could be created automatically using overprinted strokes. This does save time but allows less control on the final print and is more prone to errors (such as forgetting to add Trap to objects).

9. Trap is Not Always Necessary Link

There was no Trap created for the Dark Red text on the rocket, as it will be Overprinted on to the Orange. In situations where the printing area is small, it’s best to not create Trap as the area left open below the Overprinting color usually ends up being insignificant.

For smaller text and objects, the Trap is too small, so the object is Overprinted instead
For smaller text and objects, the Trap is too small, so the object is Overprinted instead

Again, select all the Dark Red elements and create a new spot color. If you are using non-specific colors, always supply the printer with a printed proof to allow them to match the color as closely as possible. This printed proof often helps the printer identify issues with your artwork before they move onto the expensive stage of producing film for creating the screens.

10. Checking Your Separations Link

Once you have completed the last step, you are now ready to prepare your artwork to send to the screen printer. First, you have to set the Orange and Dark Red colors to overprint. Select Windows ? Separations Preview. From the window that opens, first check the Overprint Preview box and then hide the CMYK separations by clicking the eye icon beside CMYK. The temporary dark background should disappear.

Separations Preview
Separations Preview

Check your separations by hiding each color, one at a time, starting with the Dark Red. You will notice that the Trap you created earlier is gone and the white background is only an outline. This happens because the Orange and Dark Red are not set to overprint the colors below them.

Separation of the three colors before Overprint is set
Separation of the three colors before Overprint is set

11. Setting Objects to Overprint Link

First, uncheck the Overprint Preview box in the Separations Preview window. Then, hide all the layers except the Orange layer (you can also delete the Temporary Background layer; it’s no longer needed). Select Window ? Attributes. With all the Orange objects selected, check the Overprint Fill box in the Attributes window. Do the same with the Dark Red layer, ensuring all the Dark Red objects are selected when you check the Overprint Fill box in the Attributes window.

Setting Overprint Fill on two colors
Setting Overprint Fill on two colors

12. Recheck Your Separations Link

Go back to the Separations Preview window and check the Overprint Preview box. You should now see a color variation on the artwork, where you created Trap earlier. If you also look at the White layer, you’ll see that the whole shape is left intact, due to the Orange and Dark Red set to overprint.

Left: Trap can be seen by darkened area around Orange; Right: White base returns to a solid shape (shown with temporary background for illustrative purposes)
Left: Trap can be seen by darkened area around Orange. Right: White base returns to a solid shape (shown with temporary background, for illustrative purposes)

13. Ensure There are No CMYK Objects in the Artwork Link

One thing you have to ensure before saving your file to send to the screen printer, is that there are no CMYK elements in your document. This can be checked easily by choosing File ? Print. Select your printer as Adobe Postscript File and click the Output option on the left side. Select Mode as Separations (Host-Based). On the list of colors below, if the printer icons shows next to any of the process colors (Process Cyan, Process Magenta, Process Yellow or Process Black), you have elements in your artwork which are set in CMYK colors.

Checking for CMYK objects using the print dialog box
Checking for CMYK objects using the Print dialog box

14. Finish Up and Send It Off Link

Once you are sure your Spot colors will separate as you expect them to, save your file as PDF and send it along with either a JPEG or printed proof. Sometimes printers request the original Illustrator file, in case they need to make alterations themselves. A good printer will check your files, and let you know if there’s an issue before the process of creating screens begins.

Final Note Link

There are many alternative techniques to prepare your artwork for screenprinting; today’s post concentrates on more manual techniques, for demonstration purposes and also for reliability. Your artwork will probably be output on a different hardware and software configuration to yours; the more complex your artwork, the greater the possibility of errors during output.

There are two areas you must pay close attention to: make sure you are only using spot colors, and ensure all pieces of your artwork get output by the screen printer as you expect it to.

Often, a stray object set to a CMYK value is left somewhere on your artwork, which causes one of two issues: either the screen printer outputs an extra color(s) to film (with which the screens are created), possibly incurring extra cost; or the screen printer only outputs the specified Spot colors, and part of your artwork goes missing on the final print. Use the Separations Preview window to check the different layers of your artwork, making sure colors overprint where they should and that all pieces of your artwork are present and correct.

It’s important to strike up a good relationship with your screen printer, whether they are a local company or one you found on the Web. They can give you vital advice, and could potentially spot mistakes before the screens are made or any t-shirts are printed. Also, if they’re a local business, try to get a tour of their print shop; screen printing is a great process to observe, and being familiar with the process is a great help when making design and preparation decisions.

Further Resources Link

(ik) (rs)

Footnotes Link

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John Rainsford is an Irish web designer with a penchant for web standards and printing stuff. You should follow him on Twitter, read his blog, check out his photo on Flickr or visit his place of work,

  1. 1

    Thanks for listing my article at VectorTuts as a resource. I love how detailed this article is and it’s full of some great tips.

  2. 2

    The Read Aloud Creative

    December 7, 2010 8:46 am

    This should be know for any type of printing! OKay. Litho has a higher tolerance, but definitely flexographic printing! You’d save a whole world of shit if you just used ArtPro instead on Illustrator as well!

  3. 3

    David Dilling

    December 7, 2010 7:06 am

    Excellent piece, which I just re-tweeted.

    However, one omission. One can simplify much of the checking part of the process with FlightCheck v6.76. This app is a Preflight and Packaging tool which will not only automated many of the great suggestions you made above to check for, but also helps you collect all used fonts and placed art-work into a job folder, even compressing the file for easy delivery to the printer!

    • 4

      John Rainsford

      December 7, 2010 7:46 am

      FlightCheck and Adobe’s Preflight (in Adobe Acrobat Pro) are definitely very useful for checking your print documents but are a tutorial (or seven) in themselves :) The main principle I was trying to get across in this article was to simplify where possible, at the Illustrator stage; the artwork will be printed on a relatively rough substrate and the screen printer will be doing the outputting, which will be out of your control (unfortunately). Thanks for your comments, I appreciate them!

      • 5

        David Dilling

        December 7, 2010 9:11 am

        Totally understand. You had some often over-looked, great production details in your article, which is excellent.

        • 6

          This is some really great advice! I worked in a printshop doing the registration and printing with automatic presses. Even with the added precision of a machine print, we printers still pulled our hair out over lack of trap or none at all. We would also see extra objects that the artist had forgotten to clean up before printing the separations. Even with an in-house graphic design team, these two things were constant issues.

  4. 7

    Way to switch things up! I was surprised to visit SM this morning and see this article. I’ve been screen printing for a few years now and this was definitely a good overview of the process. Thanks for a refreshing change!

  5. 8


    December 7, 2010 7:29 am

    John this great..I was in the process of getting shirts made for my website.

  6. 9

    I remember doing this the old skool method — by HAND. :-) Brought back some fond memories. AI no longer has that nasty habit of slicing curves or knocking out overlapping shapes when output to positives.

    You could take this a step further and go into process 4 color and index color seps…tho that might be a tad TOO specialized for SM.

    • 10

      John Rainsford

      December 7, 2010 8:19 am

      Rubylith FTW!

      Actually process color would be easier to write about- AI handles process artwork exceptionally well and involves very little extra work… but it’d be a lot more expensive to get printed and IMHO solid colors work so much better on t-shirts than process. Maybe next time ;)

  7. 11

    frederick Luna

    December 7, 2010 8:17 am

    – . – AWSOME John – . – and its as you said adding complexity to the artwork increase possibilities of errors.

    nice article.

  8. 12

    Spirit of Ken Richards

    December 7, 2010 8:30 am

    Fair play John,
    You should send this to every design house in Ireland!
    Its amazing how little some so called ‘Graphic Designers’ know of the limitations/ capabilities of the various printing processes.

  9. 13

    Wow. Excellent information for those of us not familiar with the process. I didn’t know what I didn’t know.

  10. 14

    Definitely bookmarking this one and sending it around. Printed. In my resource manual, and I’ve done t-shirts for years. One addition: always do a “press check” on the first one off the line.

  11. 15

    Very nice and useful post. Are you saying you can use Photoshop for something other than making your friends look fat?

  12. 16

    I really loved this tutorial!

    I had done some old school screenprint and even woodcut tshirts back in college, but I had never learned how to manage the process digitally.


  13. 17

    Great to see more Illustrator tutorials. I find this very helpful and informative. Great article John :)

  14. 18

    Jamie from Ink Brigade Screen Printing

    December 8, 2010 1:35 am

    Being the guy that outputs film at a screen printing shop, i’d just like to give a big thanks! Getting art ready for screen printing isn’t the easiest thing to explain to folks sometimes and i thought your tutorial was fantastic! Thanks!

  15. 19

    Nicholas Hammond

    December 8, 2010 12:06 pm

    In the clothing industry it seems as though a TON of designers still do not understand this process or even know how to do it. Big problem. But this is an absolutely awesome post! Definitely re-tweeting to make sure everyone I know can learn a little something :)

  16. 20

    The layering technique works good for overlaying specialty inks. One other thing on traps, I still used strokes on simple projects and sometimes reversed the stroke to the knockout. Works great on darks with white or light colored ink. Complex projects, definitely expand the strokes!
    Also in Ai, when dealing with gradients, I have to drop the percentage to at least 98% in the full coverage end, and 2-4% on the other or the gradient will not be gradual. I learned that through some trail and error on vellum.

    • 21

      John Rainsford

      December 9, 2010 2:06 am

      I agree re: strokes for traps, but what happened to me once was that I sent an artwork to a printer with strokes on objects creating the trap. Then, the printer decided to resize the artwork (without telling me) and the objects resized but the strokes remained the width that I set (why? I do not know), effectively removing the trap. It wasn’t pretty. That’s why I outlined strokes as I’ve heard references to different vector programs resizing objects and strokes separately, but I can’t pin down which ones and why.
      Make sure you talk to your printer before, during and after your job :)

      • 22

        Your stroke stayed the same because the setting “Scale Strokes & Effects” was not set on the version of Illustrator doing the modification. I would have made them reprint it on their dime if it happened to me.

        • 23

          John Rainsford

          December 14, 2010 3:01 am

          Yes, it’s the responsibility of screenprinter, but unfortunately, deadlines are usually short, so it’s best to get it right, first time :)

    • 24

      Daniel I like the tip about the gradients. When you mentioned about dropping the percentage to 98 and adding 2-4% are you referring to the Location Percentage?

  17. 25

    Being a prepress guy, this is an excellent post. It’s very rare that a file comes in properly setup, so its good to see a reputable resource.

  18. 26

    here’s another easy method of producing separations from adobe illustrator… the most important thing when doing any color seps is to make sure your colors are assigned properly. 3 different PMS blues will NOT combine magically during output to become the one spot PMS blue you really need.

    this method is best if you have access to a ‘film positive’ imagesetter, which most film-based imagesetters (used for printing negatives for printing plates) can do with an adjustment to the RIP/setter or within the desktop pub software itself.

    some art prep in Illustrator is still necessary to achieve any underprint areas or do any manual trapping

    if you place the Illustrator file inside an InDesign document, you can preview separations with InDesign’s separations pallete, and ‘print’ separations for each ‘plate’ or ‘color’ to a PDF, which can then be ripped and printed to film positive. This feature can also facilitate trapping via the software RIP and/or InDesign. you can save quite a bit of time with this method as well.

    ive also done this (for simple spot-color jobs) with a plain black and white laser printer on thin vellum sheets which were then used to burn the screens with an exposure unit. trapping done using vellum sheets must be handled differently than film, as the vellum sheets need to be held under a ‘flash unit’ to make the laser toner darker and more evenly opaque and prevent emulsion wash-out or weakening in the screen burning/development process. this changes the dimensional stability of the vellum, which makes vellum unusable for half-tone applications with a line screen ruling of over 65 lpi.

  19. 27

    One Suggestion… To avoid offsetting and keep registration tight you might wanna add Registration marks. Often printers take your file and make separations themselves and if the pre-press/screen operator doesn’t line up your separations correctly that’s when you get registration problems. Especially if you have no Register marks. Illustrator can make them for you upon exporting the file through distiller or you can make them manually. Other than that this is a decently written piece.

    • 28

      John Rainsford

      December 10, 2010 9:15 am

      If you were doing the screen printing yourself, use registration marks- absolutely. But from my experience both sending and receiving artwork for printing, printers prefer to put their own registration marks on output. Not every printer uses the same registration cross-hairs. For example offset lithography would use a .25pt thick line with 3mm offset, whereas screenprinting would use a much thicker line, or a square or circle shape even.
      It’s up to the printer to make sure registration is tight when printing- as long as you give them trap and bleed to their spec, the ball will be in their court. When in doubt, talk to your printer (your screen printer, not your laser or inkjet printer :)

      • 29

        Very true. If the files a designer sends are going to be turned into a multi-page alike publication, the positioning of reg marks is not needed at all. All that a prepress studio worker needs in this case are specified trim areas. Almost always then it is being centered by those areas and put into the template sheet. However, many designer fail to understand that some kind of are specification is needed, so if they place the registration marks here and there – it won’t hurt. At least this way guys at the printers know how to place the page correctly on the entire template sheet.
        With smaller projects or a project not filling a template, it is always better to ask the printing company first. They know better what do they need to make things work… at least most of the times.

        Anyways, the lack of registration marks is the least of the troubles for a printing technician. I used to work at the prepress studio for 2 years, seen so many (sometimes even stupid) mistakes that I’ve decided to write a book about it. Coming somewhere next year.

      • 30

        Maybe back in the day it mattered how thick the line was… its not like that anymore old man… I send artwork everywhere in the country and even to china everyday… They all require registration marks. Especially if you are layering colors for logos. The print shop may add their own register marks but they need them initially just in case the separations you send are moved inadvertently whether it be by your hand or a pre-press operator. Sending register marks has saved me countless times. As China likes to delay production by saying that you sent the artwork wrong. As long as you keep a copy of what you sent and it is correct on your end it keeps them from up-charging. And yes no register marks will delay production. :)

        • 31

          John Rainsford

          December 14, 2010 2:54 am

          I always recommend talking to your screenprinter- I recommend asking your printer before sending your files.
          Also, if your printer, regardless of where they are based (I have always had excellent working relationships with Chinese screen printers) deliberately delay production, due to an issue like no reg marks, to charge extra, then I’d go somewhere else.
          The good thing is that I’d assume you haven’t used every screenprinter in the US and China (and, the rest of the world, of course), there are lots of really good ones that will do their best to help you avoid extra charges and mistakes- communication is key.

  20. 32

    I’ve been preparing artwork for screen printing for close to 8 years at a local shop using CorelDraw. Great post on screen printing techniques with Illustrator! You covered everything that’s necessary for spot color printing. This guide will finally help me to move on over to Illustrator. Thanks!

  21. 33

    I did many many screen print design and now feeling happy to see this.

  22. 34

    This was very helpful! Thanks for the info.

  23. 35

    lots of good stuff, but not useful for someone trying to learn the process. There is no picture of the image to reference what you are talking about & I was stopped cold at step 5 when you say to apply a light color and don’t explain how to do that. How do you get the swatches window?

    I’d like to have a tutorial for someone trying to learn this.

    • 36

      John Rainsford

      February 22, 2011 9:49 am

      You might look for a ‘Using Illustrator’ tutorial- if I was to explain the basics of Illustrator, it’d easily double the length of the article and distract from the techniques in the article.

  24. 37

    Arlen Nielsen

    March 27, 2011 10:18 am

    I read your article and for the last 12 years that I’ve been doing printing, I’ve never had to worry about trapping for any print project that I’ve worked on and I’ve done hundreds which none went south.

    Don’t get me wrong, excellent article I learned a lot, but the scope of things have changed now for designers and the print shops. When InDesign came out and brought out PreFlight, that took out any potential errors on the designers end. It also set the basis of any potential problems by setting the base standards by setting the type of press which you are sending your project to i.e. web offset or sheetfed (which is standard for most work). That will set your document with the fundamentals of what is needed for any potential errors. Now all said and done, The press’ which have been around over the last 20 to 30 years have been so extremely accurate that if there was any mis-registration of any kind, there was a fundamental problem with the machine or a worn part which needed to be replaced, or the you were working with a lazy printer who just didn’t give a damn. The wonderful advent of direct to plate as given us a cleaner and more sharp image, not an increase in alignment.

    Prepress-men in the print house check the files to see if there are any warnings if there are any flags that pop up that don’t match with their system, hence trap numbers and such. If they don’t match, they adjust the numbers and send it to film or plate, then presto.

    Like I said your article is great, and by no means am I trying to take anything away from it. But for the most part, there’s a lot of extra work that is being done that is not needed anymore due to the software handling most items, pressmen adjusting for their press, and the press accuracy over the last 3 decades.


    • 38

      John Rainsford

      March 28, 2011 1:44 pm

      Hi Arlen, I’d agree that lithographic printing is incredibly accurate and that the tools supplied with InDesign, Illustrator etc make life a lot easier, but the article is about screen printing on a tshirt and screen printing still needs a lot of generous allowances and consideration, regardless of the software. Thanks for your comment though!

  25. 39

    Hi John,
    do you know where I can download the particular image, so I can walk myself step by step? thanks in advance.

  26. 41

    Great article. Save yourself some time and do not trap the artwork. If you have to trap the art for your screen printer their skill is very low. I own and operate a screen printing (t-shirt) shop and print no trapping without any problems and perfect registration. If you are designing for poster or sign screen printing then the trap method would be recommended.

  27. 42

    Great blog !!! Nice for learn skill on illustrator tutorial. Many thanks !!!


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