Poultices may be made with corn-meal, bread, starch, ground slippery elm, flax-seed meal, or, in fact, any material that will retain heat and moisture. Flax-seed meal is usually selected because it is bland and non-irritating; because it contains considerable oil, which gives it great heat-retaining properties, and because it is cheap.

All poultices should be large, from half an inch to an inch thick, applied as hot as can be borne, and renewed as soon as cold. A covering of oiled silk or thin rubber cloth is useful to prevent rapid cooling and drying.