Does anyone here have any experience synthesizing low density alumina xerogels. I am attempting to reproduce the work by Frazee and Harris (Journal of Non-Cyrstalline Solids 285 (2001) 84-89) and was wondering about the gelation time given in that paper. It claims at one point 2 h at 50 degrees is sufficent but in other parts of the paper lists 24 h as the gelation time. I was also wondering what the color the gels should appear after toluene distillation? Any help at all would be greatly appreciated.