On-screen Anti-aliasing issues illustrator
Sometimes when you create a new pattern in CS6 and repeat it there is a white hair-like line showing up on parts of the design. These lines seem to disappear if you zoom in or out. This is due to the way illustrator displays your image.
All you have to do is turn off the anti-aliasing option from your preferences.
Go to :
Illustrator > Preferences > General and un-click anti-aliasing
Now return to your pattern and no line should be showing!
You can also watch our online tutorial