I have at least one friend-colleague that'll be imposing the eponymous ashes in a service this Wednesday. (This may come as a shock to some of you, but this may well be my least favorite Christian observance, or at least the ash-imposing part.) This raises the question, how does that little smudge get on the forehead? What do you use?
First, I got commercially burnt, pulverized and sifted palm-leaf ash. Unless you're thorough, parishoners will learn the hard way how abrasive palm-leaf ash is. A little packet (available in church supply stores) for a small congregation will last for years.
Some mix the ash with oil, creating an kohl-like paste, but dry works fine and is less messy. Don't overapply. (Either way, stash a wet cloth in the lecturn because your hands will be a mess; this ash is a good way to soil your duds and the church furnishings.) You can buy a vessel that holds the ash, but that seems like overkill.
I have these little salt cellars so small they can be palmed and the imposition can be made with the thumb. Or, in another IKEA find, a fifty-cent tealight holder can fill in, but this makes the service a two-handed operation.