Screen printing has become the modern go-to printing technique. But when your beautiful design includes gradients, preparing your artwork for print quickly becomes an unexpected nightmare. Don’t worry, we’re here to help.
What you’ll need:
- The Illustrator File (CS4)
- Adobe Illustrator
- Adobe Photoshop
A Brief Definition of Screen Printing
Screen printing is a printing technique in which ink is pushed through a fine mesh screen, which has a stencil of your design.
- First, you coat the screen with a light-sensitive emulsion.
- Then, you place your photo negative image on top of the emulsified screen. Your image is printed in pure black on a transparent surface, such as a piece of transparency paper, or vellum.
- Expose the screen to a strong light source, ensuring that your image is between the light and the emulsion. The emulsion covered by your image remains unexposed, while the exposed emulsion dries.
- Remove your image, and rinse out the screen. Like magic, the previously protected emulsion washes away, leaving a stencil.
- Push your ink through the screen…
- And now you have your print!
A visual representation of the screen printing process
Screen printing is a one-color process meaning you print every color separately using a separate screen. For example, if you want to print an image with dark red & pink, you would print the dark red first (1), then print the pink (2) on top of that to create a final image (1+2):
The Problem with Gradients
Gradients present an issue in Screen printing because of the screen burning process.
With digital printing, every color is printed simultaneously & precisely with varying percentages of Cyan, Magenta, Yellow and Black. When you use a digital printer, your gradient is perfectly fine as rendered on the computer because digital printers can print gradients by merely fading out the amount of ink used:
But when preparing your file for screen printing, it is essential to use halftones because you need a pure, solid color to block the light and burn your screen correctly.
Screens also vary by mesh: a higher mesh means a screen is more tightly woven, which allows for more detail but also allows less ink to pass through; a lower mesh is the opposite, more loosely woven allowing more ink to pass through to better print large areas of color. So you can create finer, smoother gradients by using a higher mesh screen.
Halftones are the answer
Changing your gradients into halftones allows you to create the visual appearance of a smooth blend but still block light properly. When done right, halftones are only visible at very close distances:
A close up showing halftones
How to Separate Gradients Using Halftones
Before starting the tutorial, here are a few important factors to keep in mind about your future designs:
- Just like other situations, if your original file is raster, create it at actual size.
- How fine of a mesh will your screen printer be using? If your artwork is very detailed, this is a good thing to specify.
- How many colors will you use? A ten-color design might look great, but often times clients will want a more affordable option – screen printers will charge more to print additional colors.
- And of course, is your design best-suited for screen printing? Sometimes a certain design, like a photograph, just doesn’t work as a screen print. It’s okay, accept it and move on.
This tutorial is geared towards beginner to intermediate screen printers/designers and people looking for a fairly simple, straight forward process without the need of additional programs or software. In this tutorial we will be preparing a vector rose graphic for a 3-color screen print. Let’s begin.
Create Spot Colors
We will first change each color into a ‘spot’ color, so that it is no longer a CMYK mix, or Process color. This makes it easier to separate each color into it’s own layer to burn separate screens.
1. Open the ‘halftone-gradient-tutorial.ai’ file (Download above)
2. With the Selection Tool, select the rose fill, the blue to red gradient.
3. Open up your Gradient window (Window > Gradient) and select the left, cyan color stop.
4. With the color stop highlighted, go to your Color window. Click and drag the cyan box into your Swatches window to create a new cyan swatch.
5. Now select the right magenta color stop in your Gradient window.
6. Your color window should now have a magenta box. As before, click and drag the box into your Swatches window to create a new magenta swatch.
7. Deselect the rose.
8. Double click your newly created cyan swatch.
9. In the dialogue box, change Color Type from ‘Process Color’ to ‘Spot Color’ and click ‘OK’.
10. Turn the magenta swatch into a Spot Color, using the same method.
11. Reselect the rose.
12. Click and drag the cyan spot color onto the left gradient swatch. Also replace the right color stop with the magenta spot color.
13. Your rose gradient is now using both spot colors.
14. Save your progress.
Separate Your Colors
We will now separate each color to print individually. Although each color will save as black, remember that a black ink image will block light the best for screen printing. You choose the actual ink color for your image once you’re finally printing through the burned screen.
1. Go to File > Print…
2. For ‘Printer:’ choose ‘Adobe PostScript File’ and leave ‘PPD:’ as is.
3. Select ‘Output’ from the options on the left.
4. For ‘Mode’ choose ‘Separations (Host-Based)’ (This could vary depending on your printer)
5. You can leave Emulsion, Image and Printer Resolution to their default settings.
6. In the Document Ink Options, turn off every ink other than the cyan spot color, by clicking the printer icons next to each ink. See screenshot below:
7. Click ‘Save’ – Name the file ‘Cyan Spot Channel’ and click ‘Save’
8. Repeat this process to save a file for the Magenta Spot Channel, and lastly for Process Black – you should end up with 3 separate saved files.
Note: For future projects, be sure your artboard is the same size as your art, otherwise your Adobe PostScript File will be cropped.
Create the Halftones
We’re almost done, but we need to finish the process in Photoshop.
1. While still in Illustrator, go to File > Open to open one of your newly created PostScript files – I will use ‘Cyan Spot Channel’ as the example. On Mac, you must first specify Adobe PostScript files to open in Illustrator.
2. Select the black to white gradient with the Selection Tool.
3. Copy your selection.
4. Open Photoshop and create a new document. The settings should match that of your copied gradient, but just in case, the dimensions should be 2289px wide, 2269px tall, 300 ppi.
5. For ‘Color Mode’ choose Grayscale.
6. Paste the object into your Photoshop document – Paste As: Pixels – Click ‘OK’ – Hit Enter to commit to transform.
7. Hit Control + L, or Command + L on Mac, to bring up the Levels dialogue box.
8. Move the left black color stop to the beginning of the graph, around ’23′. Click ‘OK’.
9. Go to Image > Mode > Bitmap…
10. ‘Flatten Layers?’ click ‘OK’
11. Output: 300 ppi and for Method choose ‘Halftone Screen’. Click ‘OK’
12. You can leave Frequency and Angle at their defaults, but change Shape to ‘Round’ – Click ‘OK’. Note: Changing certain Bitmap settings will help you achieve your desired result, based on the amount of detail you require.
13. Go to File > Save As and save as whatever file type your printer needs – PDF’s are the most widely accepted format.
14. Simply repeat this last set of steps for both your other colors (in this case, Magenta and Black), and your files are ready to go! Note: You should make each file a different Angle for best results.
A zoomed in shot of the final screen-ready image. When zoomed in extremely close, the image will appear pixelated, but at actual print size, it works great. Again, you can also toy around with the Bitmap settings to achieve your ideal results.
If you have any comments, questions, or feedback, we would love to hear from you. Also feel free to share any tips or other strategies as to how to go about the gradient halftone separation process. Thanks for reading.
22 comments
J
December 8, 2010Is it possible to use a manual press to register something so integrated? Thank you for the info.
Brennan
December 8, 2010Hey J, it is certainly possible to register complicated screens on any press, even a manual press. Unless you want to do a lot of trial and error & just eyeball it, the best method is to use registration marks.
J
December 8, 2010Thanks for that advise. Do you know a way to simulate this process using CS2 illustrator?
Brennan
December 8, 2010Well, the closest way to simulate this process in Illustrator is to select your gradient-filled object then go to Effect > Pixelate > Color Halftone (Keep in mind this is merely a raster-Effect, giving the appearance of halftones, but not actually turning your object into vector dots). The other option is to simply do everything in this tutorial up until the Photoshop section. Under the ‘Separate Your Colors’ section, look at step number 6. You’ll notice you have a number of other options in the ‘Document Ink Options’, including changing ‘Dot Shape.’ Simply change the Dot Shape to either a circle or ellipse, and this will mimic the Photoshop effect.
Jene'
January 10, 2011Is it different if I am doing this in CS5? I am having a hard time separating a gradient of a dark blue and a light blue. Only part of the light blue shows up when I re-open it in photoshop and the same happens for the dark blue.
Brennan
January 10, 2011Hey Jene’,
I actually created this tutorial in CS5, but made a CS4 file available to include people who don’t yet have CS5. My only guess is that your colors are too similar. Because you are preparing this for screen-printing, it actually doesn’t matter what on screen colors you use, so you might have better luck if you use more opposite colors, for example, cyan and magenta. I would think changing the color swatches into spot colors would keep them separate, but maybe not. Try using 2 opposite colors, but feel free to let me know if this doesn’t fix the problem.
Innovative Ink
February 9, 2011Very informative…you went in depth into the process. Will be checking back often.
Jesse
March 14, 2011Just to be clear, this tutorial assumes you have a vector image to begin with right?
How would you approach the situation if you only had a raster file?
Brennan
March 14, 2011Hey Jesse,
Yes, this tutorial shows the process starting with a vector image. I find that if you’re starting from scratch, vector art translates very well to Screen Printing, due to the ease of color separation, and you can easily plan out how it’ll print. No matter if you’re using vector or raster art, it’s always best to know how you will eventually be printing it, so that you can create your art accordingly.
With that said, you can definitely start with a raster file. Let’s take a full-color photo for example. Make sure the file is full-size, and open it in Photoshop. Ensure that your color mode is CMYK (Image > Mode > CMYK Color) and at 300dpi. Open the Channels Window (Window > Channels) which shows you the CMYK channel (all 4 inks), then each of the four separated out.
Hide every channel except one (like Yellow for example). Select All, copy, create a new document (it should have the same dimensions as what you just copied, but make sure Color Mode: Grayscale). Paste your artwork into the new document, and you should have the single channel (in this example, just the Yellow channel). From here, just repeat the tutorial instructions, beginning at Step 9 under the “Create the Halftones” Section to create your screen. Repeat this for all 4 CMYK channels, and you will end up with 4 screens – print them in their corresponding colors to create a full-color screen print.
Hopefully that helps!
Jesse
March 15, 2011Hi, thanks for answering my question! I really appreciate it.
I am actually working with water based inks so that kinda rules out 4 color process (at least for the level of printing I’m at). Is there another way you would approach a raster image with several gradients? I’ve tried using the color range but it is rather ineffective when there are several gradients in the image.
Would it be alright if I e-mailed you the artwork of what I have been working on so you can see what I’m talking about?
Brennan
March 16, 2011Jesse, that would be very helpful. Go ahead and send it to: info@3roadsmedia.com, with a descriptive subject line, and I will see what advice I can provide.
Oliver
July 28, 2011Hi,
Thanks for the advice. When I try to copy my gradient shapes into photoshop they are coming out as gradient filled rectangles instead of the shapes.
Any ideas?
Brennan
July 28, 2011Hey Oliver,
I just tried to recreate the technical issue you’ve described. Once you have your PostScript file open in Illustrator, be sure that you’re selecting your object using the Selection Tool and not the Direct Selection Tool. When I copied the object using the Direct Selection Tool, it pasted a rectangle into Photoshop, as you described. So again, my only guess would be to ensure that you’re selecting your object using the Selection Tool. Hope that helps!
debbie
August 8, 2011I have a black and white photo I wish to make into a halftone to print a one color silkscreen image (black ink on white shirt) or white ink on black shirt) how do I produce a halftone image of the photo?
Brennan
August 9, 2011Hey Debbie,
Thanks for the comment. A black and white photo is actually pretty easy to convert into a halftone pattern. Open your image in Photoshop (try to make it actual size, like 8″x8″ for a decent t-shirt size, for example, at 300 dpi). Also, be sure you are in Grayscale Color Mode. With your photo open, go to Image > Adjustments > Levels to darken your blacks and increase contrast. Then go to Filter > Pixelate > Color Halftone. Change your Max. Radius to “4″ (you can use a higher radius for less detailed photos), and leave the Screen Angles on their default settings; Click “OK” and you should be all set.
Brennan
דפוס
September 6, 2011thanks a lot.. these are really good tips for the whole printing industry
braderj
October 2, 2011Hi there..nice tut u have there..
Can u elaborate more about this “Note: You should make each file a different Angle for best results.” How can we know what is best for each design? Thanks in advance.
Brennan
October 12, 2011Hey braderj,
To be honest, I have not looked into screen angles at great length, I just know that by having screens at different angles from each other will allow for more thorough coverage and you won’t have as many empty spaces. Wish I could be of more help.
Brennan
Alec
October 12, 2011Is it possoble to screen print an image made using gradient mesh?
Brennan
October 13, 2011Hey Alec, I am not too familiar with the gradient mesh tool, but I’d imagine it’s the same principle. Juts use spot colors and finish the process in Photoshop.
jo
October 17, 2011It’s funny how everyone has different ways to do things that work for them.
In more than one industry course, I was told to always use 45 frequency, 61 angle, elliptical dot for all halftones always.
I did a nice 2 color gradient but there was not full coverage. In this case I got around that by being able to use a nice garment color that worked. But of course I won’t usually have that liberty.
here’s my questions.
I wouldn’t really know this until I print it. Is there a work around?
If I change angles what do I change them to?
Brennan
October 18, 2011Hey jo, thanks for the comment. As mentioned in this tutorial, this is really meant for beginners and designers who want a quick fix for working with gradients. I am not extremely knowledgeable with specific, ideal screen angles. However, I have found that local screen printers are often times very helpful and friendly when it comes to questions like this, so my only recommendation would be to call someone local and see if they’re willing to answer your questions. Good luck!
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Screen Printing Guy
November 25, 2010[...] 3 Roads Blog has created a tutorial on Separating Gradients for Screen Printing Using Halftones. Click here To Check It Out [...]
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April 23, 2011[...] halftones simplified- awesome help to me… Here is a link that I think that spells it right out, you need illustrator and paint-shop, but i printed a great black halftone transparency with a Kodak 3200. Hope this helps someone like it did me.. Carl How to Separate Gradients for Screen Printing Using Halftones | 3 Roads Media Blog [...]
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