Level | Cellulose nitrate | Cellulose acetate |
---|---|---|
1 | No visible deterioration | No visible deterioration |
2 | Film base turns yellow, and image shows signs of mirroring | Film base begins to curl and can turn red or blue |
3 | Film base becomes sticky and gives off a strong smell of nitric acid | Film base shrinks, becomes brittle and produces acetic acid (vinegar smell) |
4 | Film base becomes amber in colour and the image begins to fade | Film base can begin warping |
5 | Film softens and can weld to adjacent material or enclosure | Film base forms bubbles and crystals |
6 | Film turns into a brown acid powder | Film base forms channels |