Aluminum windows, including storm windows, are lightweight alternatives to heavier window materials. However, like all windows, aluminum windows can develop problems over time. If the windows are not adequately maintained, it may become more difficult to slide the panes. If you have aluminum windows that meet with resistance when moving the panes, there are steps you can take to make them slide more freely once again.
Brush and clean the windows. Start by removing any dirt or debris around the windows, in the frame and in any tracks or channels. You can use a vacuum, brush or a damp cloth depending on the amount of dirt and debris present. You can also use a cloth or brush with a small amount of detergent dissolved in a bucket of water.
Treat with a lubricant. There are a variety of lubricants you can use for aluminum windows, but a silicone-based lubricant that will not corrode the metal is a good choice. Spray the lubricant in the window tracks, and move the panes back and forth to spread the lubricant over the parts you cannot spray. Repeat this several several times until the window slides freely.
Wax the frame. Once your windows are clean, you can use an automotive wax on the metal frame and channels. The wax will not damage the metal and will serve to protect it against corrosion.