Distinguishing between film, open-reel audio tape, and open-reel video tape

If you look closely at film, you can see images in each frame that are readable to the human eye (though tiny). Information recorded on audio and video tape is not human-readable. Video tape is usually matte black, while audio tape is usually a matte reddish-brown or black color. If it says "video" anywhere on the media label, it’s not film. Film will also have little notches/holes along the edge, while audio and video tape will not.

Identifying nitrate film

Please examine any film in collections based on the following criteria: 

• Date: The use of nitrate film stock was discontinued after 1952. Any film dating from the 1890s through the mid-1950s should be examined out of caution.
  
  
• Film width: Take a ruler and measure the width of the film in millimeters from outer edge to outer edge. If you have any measurement other than 35mm (or slightly less if the film has shrunk), then chances are you do not have nitrate film. 
  
  
• Frames: Unroll a few strands of the film to look at the images. If the frames stretch from one side of the sprocket holes (the little notches/holes along the edge) to the other, it is silent film and more likely to be nitrate.
  
  
• Labels: Some nitrate film might have a star or the words "nitrate film" printed along the film edge, and/or horizontal dashes between every fourth sprocket hole.