Both fibreglass and plaster casts are applied to injured limbs to immobilise them and allow the bones, ligaments, tendons or muscles to heal after an injury such as a break, sprain or dislocation. They are also applied after surgical procedures including correction of club foot and other congenital limb deformities. While fibreglass is usually the material of choice in the United States, plaster casts still are used for orthopaedic immobilisation.
Differences in Composition
Plaster cast material is made from a type of naturally occurring gypsum known as plaster of Paris that is used to coat fibre bandages. Fibreglass casting tape is made from woven fibreglass that is coated with polyurethane resin.
Differences in Appearance
A plaster cast is smooth and always white as only white plaster of Paris bandages are available. A fibreglass cast is webbed in texture and appearance and it is often coloured. Common fibreglass cast colours include blue, pink and green. Both types of casts can be and often are signed and decorated with felt tip markers.
Differences in Weight, Strength and Durability
Fibreglass casts are lighter and stronger than plaster casts. They also last longer as they are more resistant to water damage and wear. However, neither type of cast is waterproof, unless a specific waterproof lining is used with a fibreglass cast.
Porosity, Drying Time and Flexibility
Fibreglass is more porous than plaster, so that a fibreglass cast is often more comfortable to wear. In addition, a fibreglass cast takes 30 minutes to two hours to dry as opposed to up to 48 hours for a plaster cast. However, plaster is easier to mould than fibreglass.
Plaster is less expensive than fibreglass. Some insurance plans may not cover the cost of a fibreglass cast.