Have you ever wanted to screen print CMYK, but didn't know where to start? Here's a crash course. In the video, print expert Colin Huggins shows you how to do CMYK color separation in Photoshop and how to screen print a photo in CMYK using water-based inks.
CMYK printing is done by layering four colors (cyan, magenta, yellow, and black) on top of each other to re-create art or a realistic image with only four screens. You can print CMYK with both plastisol and water-based inks.
CMYK printing is best done on white or light garments. When printed through high mesh counts like 305, the inks are translucent, and will not show up on dark garments at all. Because these inks are so translucent, thousands of colors can be created by layering just four inks.
In the broadest sense, designing for CMYK means that you need to convert an image to a CMYK color space and adjust colors if needed. This process starts and stops in Adobe Photoshop.
DESIGN BASICS IN PHOTOSHOP
Every image is different, so most education around CMYK printing either focuses on color corrections in general or pinpointing issues in a certain piece of artwork. As all images are different, they will all need a slightly different approach. In the video, Colin chose a bright image of multicolor roses for this job.
To prepare the artwork for printing, Colin has a few tasks to do first.
DOWNLOAD CMYK PROFILE
Head to “Edit” and “Color Settings” on the right hand side of the color settings window. Click the “Load” button and load your color profile to Photoshop. It’ll show up in your CMYK settings in that color window.
CONVERT TO CMYK
With CMYK printing, you can print photorealistic images. When you want to screen print an image, whether from a photo taken from your phone or found on the internet, it’ll start as an RGB image. In order to make this something you can print, you’ll need to turn the RGB colors into CMYK colors.
Converting an RGB image to CMYK is pretty straightforward. Simply go to “Image” and “Mode,” scroll to “CMYK Color” and hit “OK” in the pop up window.
Depending on your image, the CMYK conversion will be significantly more dull than the original. You are always going to experience some color shift. How much shift happens depends on the image you’re using. When you convert an image into CMYK, Photoshop needs to re-color the design using the four colors specified in your CMYK profile.
CMYK color profiles for textile screen printing do not hit the same breadth of color that other inks do. To see which colors CMYK isn’t able to reproduce, you’ll need to check for “Out of Gamut” colors. Go to “View” and scroll down to “Gamut Warnings.” When you click it, grey will show up in your image. The grey indicates which colors cannot be reproduced in the CMYK profile you’ve loaded.
Another way to see if a color is out of gamut is by using the eyedropper tool and looking at your info window. When you see an exclamation point next to the color readout, it means that color is not reproducible, and the settings shown are the maximum photoshop can provide.
Many of the colors in this image are out of the CMYK gamut and will need to be adjusted by hand.
Colin switches through different CMYK profiles to illustrate how much colors can shift based on which CMYK profile you’re using. If and when you have colors out of gamut, you’ll have to make adjustments manually. If you are looking at being “color accurate” on press, then you will need to go back in and make adjustments to the colors that shifted. We’ll cover that a little later.
MANUALLY ALTERING COLORS
Because so many colors are out of gamut in this image, the best way to get the CMYK image closest to the original is to alter it manually. To start this process, head up to the “Image” tab again. Scroll to the “Adjustments” tab and click “Selective Color.” This will bring up a pop-up window that allows you to adjust primary colors that affect the CMYK image. You can adjust red, yellow, green, cyan, blue, magenta, white, neutral, and black. This method is the primary way of getting into core color spaces to improve color balance.
Each core color is made up of four sliders: cyan, magenta, yellow, and black. You can adjust a color as much as you want and still be able to print it with the CMYK inks you have. When you select any of the core colors and move the slider left and right, all of that color in the image adjusts as well. Colin illustrates this with the red color: he selects the cyan slider within the red core color and moves it all the way to the right and left. The cyan in the entire image becomes saturated or disappears depending on the slider’s position and percentage of saturation. When adjusting colors, it’s always a good habit to maximize and minimize the sliders to see how much you have to work with.
Colin walks through adjusting all the core colors in the image by hand: red, yellow, green, cyan, royal blue, magenta, white, neutral, and black. Every image is different, and you have to be patient and willing to play around with the image to get it looking the way you like it.
Some colors aren’t reproducible in the CMYK color gamut. Colors like bright reds, greens, and teals will look a little faded no matter what you do. Make sure you test each slider to see how much difference it makes before you move on to the next color.
Adjusting every core color in your design can help you more closely match the original.
If you’re looking to go one step further to take your design as close to the original as possible, open up your curves window by selecting a layer and hitting “Command M” on your keyboard. By adjusting the curves in your shadows, you can create depth that is missing from the converted image. This isn’t necessary, but can be helpful if you feel that your CMYK image is missing something from the original.
Once you’re happy with the colors in your design, check out the color separations on the far right menu in Photoshop. You should have four separation layers—black, yellow, magenta, and cyan—and a “CMYK” layer that shows your design in color.
You can sharpen the contrast in individual layers. To do this, choose the layer that has the best contrast. Colin then performs an “Unsharp Mask.” This feature will give greater edge contrast to your design. Click on the layer you want to unsharpen. Go to “Filter,” “Sharpen,” and “Unsharp Mask.”
Colin applies the unsharp mask to the cyan layer to give the cyans a little sharper edge quality.
When it’s all finished, Colin compares the two images. The RGB image on the left is more vibrant than the CMYK image on the right, but considering that most of the colors were out of gamut for the CMYK profile, he’s happy with the results. Now it’s time to print the films.
Adjusting shadow curves can bring back some density in the CMYK image.
Printing films for CMYK artwork is just like any other job. You’ll need to print films for every color: cyan, magenta, yellow, and black. Make sure you have registration marks so you can properly register your print on press.
To print CMYK, start printing with the lighter colors and end with darker colors. Set up off contact to be 1/16 of an inch. If you’re printing on a manual press, the squeegee should be at a 10-15 degree angle and apply good pressure. Adjust based on what you see on the shirt.
Let’s talk about garments for a minute. Since CMYK inks are translucent, you’ll be able to see any rough texture through the inks. For that reason, you’ll want to use a smooth fabric like a ringspun garment to print on, as this will minimize the amount of texture or bumps you’ll see through the ink.
Colin prints with water-based CMYK process inks. Speed and consistency are both super important when printing water-based inks. Water-based ink can dry out during the run. Because of this, Colin uses the wet-on-wet technique to print. To help maintain the moisture in the inks, keep a spray bottle of water nearby to rehydrate your inks if they start to dry out. Keeping the ink wet is important, especially when printing fine detail. You’ll start to lose fine detail throughout your print run as the ink dries in the small dots. If needed, clean your screen between prints before continuing.
To print CMYK, you want to do as few print passes as possible. That way, you won’t oversaturate your screen. As Colin prints, the image loses a little bit of color density. In your first test print, you might notice that the design looks faded. This will happen in your shirts until you reach an equilibrium with your inks. Usually, that equilibrium happens at around five test prints. If your print looks correct after just the first couple of shirts, you’ll end up oversaturing your design by the end of the run.
After confirming the design on a test pellon, Colin prints on 100% cotton promo weight t-shirts. The weave of the fabric will leave a lot more open space than a test pellon will. The density of your final print on a garment might not be what you experienced on the test pellon, and you won’t be able to resolve as much detail.
When printing on a ringspun triblend garment, the image is more saturated than the cotton shirt. Triblend shirts are much smoother than cotton shirts and mimic the test pellon print more closely. There is a limit to what you can accomplish with CMYK on a t-shirt. As long as you’re happy and your customer is happy with the outcome, don’t sweat the small stuff too much.
Printing with CMYK doesn’t have to be stressful. It all starts in the design phase. As always, practice makes perfect. The more you print this way, the better you’ll get.