A method is provided for changing the visible light transmittance of a coated article having a functional coating having at least one anti-reflective material and at least one infrared reflective material. The anti-reflective material includes an alloying material capable of combining or alloying with the infrared reflective material. A protective coating is deposited over the functional coating to prevent or retard the diffusion of atmospheric gas and/or vapor into the functional coating. The coated article is heated to a temperature sufficient to cause at least some of the alloying material to combine with at least some of the infrared reflective material to form a substance having a different visible light transmittance than the infrared reflective material.