The main causes of damage to brasses are:
In floor brasses,
- wear from footsteps or the moving of furniture causing dents and scratches
- loose mountings leading to bending, flexing and weakening of the brass
- unsuitable matting accumulating damp
- grit and dirt under matting causing scratching
- Carpeting of floors where the carpet has an impermeable backing, such as rubber, causes damage to floor monuments underneath, including corrosion to monumental brasses. Such carpeting also drives moisture into the walls, leading to damaging levels of moisture in wall monuments.
- Damp: brass, an alloy of copper and zinc, is sensitive to moisture and develops a brown tarnish and green copper corrosion products.
- Dust can contain chemical contaminants and can also hold moisture on brass surfaces which causes them to corrode, even under appropriate conditions.
- Other materials such as iron nails or lime plaster touching a wall brass can cause corrosion.
- Frequent touching: the salts and grease from fingerprints can corrode brass surfaces
- Over-zealous cleaning can blur and wear away the design
- Bat droppings can badly damage uncovered brasses.