Despite their names, both cast iron and wrought iron are actually alloys, meaning they contain certain amounts of other materials in addition to iron. Cast iron is usually 2 to 4% carbon and contains small amounts of silicon, manganese and occasionally sulfur and phosphorus. Cast iron is made either by smelting iron ore or pig iron (an intermediate iron ore product) then mixing it with carbon and other metal alloys.

Another factor that works in favor of colored aluminium window frames is their comparative superiority over other materials. Take examples of fiberglass, vinyl, and wood frames; aluminum works well then all of them. A big reason for this is aluminium reduces heat and cold. The surface of colored aluminium window frames is most often endowed with thermally-improved qualities. This particular facet makes colored these work well with improved energy efficiency.