The ritual drawing of the boundary of the magic circle – also known as "casting the circle" – is usually done with either a ritual sword or an athame, in traditional coven practice. For open rituals in public places, this is sometimes done with a ritual wand or staff instead, since there may be legal complications involved with swords and daggers in public places, even when the edges have been dulled. In most traditional covens, the athame is associated with the magical element of fire, so the circle is considered to be cast in etheric fire. This fire is traditionally envisioned as blue, indigo or violet; although it may equally well be envisioned as other colors. When the circle is ritually purified after being cast, that is traditionally done with the remaining three elements—air (incense), water (salt-water), and earth (salt) – because the element of fire has already been imbued into the circle during the casting, by the use of the athame.