A method of preparing a rod for use in the preparation of a smoking article is described. The rod has a first end and a second end. The rod has located therein a solid support. The solid support extends in a linear fashion from the first end of said rod to the second end of said rod. At least a portion of said solid support is coated and/or impregnated with an additive. The rod is prepared using rod forming means, wherein said rod forming means comprises a channel ending in an open exit, wherein material may pass through at least part of the channel and leave via the open exit in the form of a rod.