When choosing a PET base film, there are several considerations to consider. These include cellulose nitrate and cellulose diacetate. In the darkroom, these points are not as important. However, if you're loading film in bulk with a daylight loader, you should pay particular attention to the last few frames. Similarly, you should test any cassette with a protruding tongue.

Cellulose nitrate is a film-forming polymer. However, the degradation process of this material produces nitrous oxides, which are corrosive acid gases. They can damage metals and organic materials. Moreover, nitrate gases have low odour warning properties. This means that they can exist in high concentrations before their smell becomes apparent. In fact, chronic exposure to these gases can lead to headaches, blurred vision, and even emphysema.

When disposed of, cellulose nitrate film should only be disposed of by a professional agency. In addition, it should never be thrown away in a conventional trash container. This is because cellulose nitrate is flammable. It is essential to follow NFPA 40 guidelines when disposing of this film.

The production of cellulose nitrate film was discontinued in 1951, primarily due to its chemical instability. However, new plastic film bases, cellulose acetate, and polyester, were developed and remain in use today. They are the basis for many different products. So, if you're considering getting some cellulose nitrate film, make sure you read the label carefully.

Choosing the right plastic film base is vital for the long-term survival of your negative collection. Unfortunately, some plastic film bases can be very difficult to identify. However, there are some clues that can help you identify the correct one. Look for the tone and thickness of the film, as these can be indicative of the plastic type. If the tones of the film are a similar color, then the negative is probably cellulose acetate.