The oval brushes are fine - think about it, there is clearance between the frame and the reveal, the bristles splay out enough to get into the corners, bit easier with a square brush but by no means difficult with an oval brush. Try a tucker dual trim/salmon/vikan square if the ionics is no good, but judging by what people have been saying for a while on cleanitup Ionics need to have another look at their brushes.