This mostly happens with pigmented ink – where the particles of colourant are too large to be absorbed into the surface of the inkjet paper.

Another cause can be where two different types of ink are used in the printer at the same time. For example if you have the Canon Pixma IP 8500 (this printer uses eight different ink cartridges) and you use half original Canon cartridges (B/C/M/Y) and half compatible ink cartridges (Photo Cyan/Magenta, Red and Green) the different formulations of ink can cause problems. The ink mixes in the printer head and because different manufacturers of ink will produce different qualities they won’t always interact together properly. We always advise customers to use either a full set of original cartridges or a full set of compatibles, if this is the case then the ink will mix properly and avoid similar problems that happen if you try to mix oil and water!