Covered or filled (with something foaming or resembling foam).
1988, Charlotte MacLeod (as Alisa Craig), The Grub-and-Stakers Pinch a Poke, New York: Avon, Chapter 6, p. 48,
[…] Minerva […] arrived with a huge armload of costumes, followed by Zilla and a couple more, all afoam with petticoats.
2000, Jan Thornhill, “Extremes” in Drought & Other Stories, Dunvegan, ON: Cormorant Books, p. 126,
Margot’s thick black hair afoam with Spic and Span, swooshing back and forth across a grimy kitchen floor