As used in fine art inkjet paper, fumed alumina is alumina that has been formed by
the high temperature hydrolysis of gaseous aluminum trichloride so that it forms highly pure alumina particles. These particles have a nanometer scale primary particle size (average about 13 nm), with a very narrow particle size distribution. While these particles have no internal surface, they have a very high surface area-to-volume ratio and tend to have a specific surface area of about 75 m 2 /g. Unlike fumed silica, which has an anionic surface charge and which tends to be amorphous, fumed alumina has a cationic surface charge and is crystalline in form. The high specific surface area with a lot of accessible cationic sites helps to fix the anionic inkjet dyes and the crystalline nature of the particles contributes to the glossing potential of the coated inkjet paper surface.