The present disclosure provides an example where a non-Newtonian white ink can include an aqueous ink vehicle, from 5 wt % to 60 wt % of white colorant, and from 0.1 wt % to 5 wt % of amphoteric alumina particles dispersed in the aqueous ink vehicle. The white colorant can include white metal oxide pigment having an average particulate size from 100 nm to 2,000 nm, an alumina coating on the white metal oxide pigment forming an alumina-coated pigment, and a polymeric dispersant associated with a surface of the alumina-coated pigment. The amphoteric alumina particles can have an average particles size from 2 nm to less than 100 nm.