In rotogravure print, we are reversely printing on film up to 10 colors from the darkest color to the lighter one. Yes, darkest print first cause we print inside the film not outside to protect the ink from scratching.
We print CMYK process color for photo and spot color for illustration art, background color, important color such as the logo.
So for the area of Spot color and Process color overlap, we need to do “special treatment” – adding trapping to avoid seeing the misregistration. Misregistration is inevitable but we are controlled within +/- 0.2mm.
To avoid adding keyline, packaging designer can:
1. use a darker spot color design over on the CMYK background
2. use fewer numbers of color in one design
3. use less sophisticated design
Having said that, our design team can help to print the design at minimum change. Whatsmore, working with your packaging printer in the artwork development phase is always the best practice to understand the printing limit, material effect, the special aesthetic addons that can be chosen from such as stamp foil, matt, holographic, etc.
By the way, using digital print can ignore the keyline problem