Salt can work, but can cause trouble with analyses as pointed out by Simon. I would also avoid ethanol because it can also lead to variable changes in delta values - we summarized this in Versteegh et al. (2011).
We have had good results with simply sun drying in a place where there is a good breeze (such as a window sill).
Versteegh, E.A.A., D. P. Gillikin and F. Dehairs (2011). Analysis of $B&D(B15N values in mollusk shell organic matrix by EA-IRMS without acidification: an evaluation and effects of long-term preservation. Rapid Communications in Mass Spectrometry 25: 675-680. doi: 10.1002/rcm.4905
David P. Gillikin, Ph.D.
Associate Professor of Geology
Director: Union Stable Isotope Laboratory
Department of Geology
807 Union St.
Schenectady, NY 12308
Office phone: (518) 388-6679
Lab phone: (518) 388-8741
Lab Website: http://minerva.union.edu/gillikid/lab.htm