<p>A domed cleaning appliance filter assembly (22) comprises a sheet (20) of filter medium folded along a fold pattern comprising a plurality of rows of zig-zag lines having alternating vertices and a plurality of rows of straight lines running transverse to the rows of zig-zag lines and passing through the vertices. The zig-zag lines comprise alternating lines of a first type and a second type, the first type of zig-zag line having vertices of a first angle and the second type of zig-zag line having vertices of a second angle different from the first angle.</p>
