Plastic abrasive is used extensively in the aerospace industry where it has virtually replaced all chemical strippers. This is also likely to happen in the masonry cleaning industry because of growing controls on disposal of chemicals in local sewers. Plastic abrasive is generally made from plastic off cuts, usually the acrylic thermoplastic (type 5) kind. It has very low specific gravity and hardness, and it must be used in specialised equipment because of its poor flow characteristics. If used correctly, plastic abrasive will remove difficult coatings without damage to delicate substrates such as titanium, aluminium, and anodised and cadmium-plated surfaces.