The onset of degradation is unpredictable and rapid. It can manifest itself in an advanced state apparently almost overnight. It is irreversible and in most cases, once started, unstoppable. The best that can be achieved is to slow down the process.
Degradation products from objects (e.g. acidic vapours) can contaminate other objects in the vicinity. Collections should be checked regularly, ideally at least once a year, and any object showing signs of degradation should be separated from the rest of the collection.
Causes and effects of degradation:
- excessive humidity can cause chemical breakdown of certain plastics.
- fluctuating temperature and humidity, cause shrinkage and expansion, which in turn results in crazing and cracks.
- migration and loss of plasticizers, cause surface bloom and /or surface tackiness and then to loss of flexibility and embrittlement.
- pollutants and exhaustion of stablisers cause chemical break down of the material's structure and, ultimately, collapse.
- light causes darkening, loss of flexibility and embrittlement of the plastic and fading of pigments.
- bad handling leads to chips, cracks and breaks.
Early signs of degradation can include:
- bloom, a white powder of the surface.
- corrosion of metal parts or surrounding objects.
- crazing and cracking.
- discoloured or even shredded packaging materials.
- distortion of the shape of the object.
- smells: mothballs (camphor), sweetness vinegar, vomit, rancid butter.
- Surface stickiness.
- Haze, a wet acidic deposit on the surface.
If you think an object may be degrading wrap it in charcoal cloth and store it away from other objects.