To understand why the ink coverage of your file is important, it is good to know what ink coverage is. Ink coverage is the amount of ink that is used for your printing. If too much ink is used, it could cause staining on the print. In this article you can read how you can prevent this from happening.
Printing is done by using four colours: Cyaan, Magentha, Yellow and Black (Key). If, for example, a yellow square is required, you could use 100% Yellow. This means the ink coverage is 100%. A yellow plane is easy, because yellow is 1 of the 4 colours from CMYK. If you want an orange plane however, you use 100% yellow and 40% Magentha (pink). The total ink coverage is 140% in this situation.
Watch out for a high ink coverage
Files that contain an ink coverage above 300% can develop stains. This is why we recommend to not use a higher ink coverage then 280%. For black text it is recommended to 'just' use 100% black (K).
Dark images often have a high ink coverage. This happens because black (key) is not the only colour that is being used. In this situation, all of the colours will be used. This means the ink coverage is above 280% and thus increases the probability of staining.
But how do you adjust ink coverage?
You can adjust the ink coverage of your file by changing the colour profile in Adobe Photoshop. This is done by using the following method:
Step 1: Open your file that has high ink coverage in Photoshop.
Step 2: Go to the colour settings menu in Photoshop.
Click Edit and then go to colour settings. The key combination Shift + Cmd + K may also be used to do this.
Step 3: Click CMYK and select the option Adjusted CMYK.
Step 4: Set the ink limit.
A menu will appear containing the colour separation option at the bottom. Set the limit of black ink to 100%. Set the total ink limit to 280% and click OK.
PAY ATTENTION: you are not finished yet. The next step is very important
Step 5: Change the colour mode
You always need to change the colour mode, because the settings that you've just set won't be used otherwise. The colour mode needs to be changed to CMYK. Is the colour mode already in CMYK? Then you still need to change it. This is explained in the text below.
You can change the colour mode by going to Images -> Mode -> CMYK. Is it already set on CMYK? Then change it to RGB, and change it back to CMYK. If this isn't done and the colour mode is kept on CMYK, Photoshop will use the old CMYK settings and then all your trouble will be for nothing.
Step 6: Click OK
Step 7: Save your file as TIFF or PDF
Go to File -> Save as, or use the key combination Shift + Cmd + S. Select the appropriate extension at the format.
- What is the maximum amount of ink coverage?
- What is the minimal amount of ink coverage?
- How do I convert a file from RGB to CMYK in Photoshop?