I consulted Advanced Practical Organic Chemistry (John Leonard) and Practical Organic Synthesis (Reinhart Keese). Both have useful paragraphs on dry loading, but one point is not clear. Does one use sand, and if so, is the sand above or below the sample-impregnated silica?
Sand on top of the sample loaded silica. So I make up the column, either wet or dry load, then add a bunch of sand, enough to protect the sample loaded silica so my cack-handed pouring of solvent doesnt disturb the sample layer.