In the late 1800s iron bed makers encouraged consumers to "wage war on dust, disease or vermin" by using a more sanitary iron bed. In addition to a "more sanitary condition," iron bed frames offered consumers elegant, beautiful designs that many wooden beds couldn't compete with. Because iron is a durable material that is less subject to breakage, many of these beds may be found in antique stores as well as city dumps today. If you have found a potential antique, you must study it closely to determine the date.
Look at the metal involved in creating the bed. The Victorians primarily used hand-crafted cast iron for their home products until the start of World War I. This included bed frames, headboards and foot boards. After that point, mass-produced beds made of aluminum were common. If your bed frame is made of aluminum instead of iron, it is a reproduction.
Look through antiques stores for bed frames in similar styles. Bed frames made in similar styles can date from the same time period. Some of the design styles that rose to prominence when Iron beds were popular include the Victorian style of the mid-1800s, the Art Nouveau style of the late 19th century and the Art Deco style of the 1920s and 1930s. Iron-bed frames created in these styles may date to these time periods.
Examine the bed for an impression, trade mark or stamp that identifies the manufacturer. This mark may include a date of manufacture. If the maker is no longer in business, you can narrow the date of the bed to the time period before the manufacture closed. Consult antiques books for a record of bed designs made by that manufacturer. Many furniture makers change their designs over time. An individual piece of furniture's design helps to narrow the date of manufacture down.
Look at the structure of the bed. Antique iron beds were built into the frame. They generally consisted of a headboard and foot board and side rails. The side rails connected to the head and foot board with hitches instead of brackets. If your bed has a separate frame or brackets for hardware, it may be a reproduction. Antique beds were also larger in size. A full/double antique bed from the Victorian era would be the equivalent of a modern queen or king sized bed.