Canon iP1800 Series - Manual (Page 21)

17 Routine Maintenance
Examining the Nozzle Check Pattern
Examine the nozzle check pattern output by the printer, and clean the Print Head if necessary.
1
Confirm the printed nozzle check pattern.
(1) If lines of this pattern are missing, the print head nozzle needs cleaning.
Example: When lines are missing (Black ink)
(2) If these patterns have white streaks, the print head nozzle needs cleaning.
Example: When white streaks appear (Color ink)
Note
The nozzle check pattern will not be printed correctly if there is not enough ink. Replace the FINE
Cartridge if the remaining amount of ink is insufficient.
See “Replacing a FINE Cartridge” on page 26.
(2)
(1)