A method of coating a substrate with a washcoat is disclosed. The method comprises engaging the substrate with a headset of a substrate coating apparatus so as to locate an upper surface of the substrate below a washcoat showerhead of the substrate coating apparatus; and discharging a washcoat out of the washcoat showerhead towards the upper surface of the substrate; and drawing the washcoat through the substrate by applying a suction force to a lower surface of the substrate.