The currently available infrared data on scattered light from the dust comae of Cernis and Bowell set stringent upper limits to the contribution of icy grains. For Comet Cernis the data is consistent with only a 10% mass fraction of water-ice included within silicate-organic-carbon grains of scale radius 15 microns, while for Comet Bowell there is no evidence for any ice component. A coma of small (10–100Μm) organic grains containing a fraction of OH-bearing molecules that evaporate over weeks at 5 AU and leave an absorptive carbonaceous grain residue is the simplest model for Comet Bowell.