| abstract |
A recording ink including a colorant dispersible in water, a humectant, a surfactant, and a wetting agent, wherein the rate of viscosity increase associated with evaporation of moisture in the recording ink is 5.0 mPa·s/% or less while the evaporated moisture content is less than 30% by weight based on the whole weight of the recording ink, the rate of viscosity increase associated with evaporation of moisture exceeds 50 mPa·s/% while the evaporated moisture content is 30 to 45% by weight, and the average particle size of the colorant in the recording ink is less than five times the average particle size of the colorant in the initial recording ink, and is 0.8 μm or less, at the stage of the recording ink when the rate of viscosity increase amounts to 50 mPa·s/%, wherein the rate of viscosity increase associated with evaporation of moisture (mPa·s/%) is defined as the increment of viscosity (mPa·s) versus the increment of evaporated moisture content (%). |