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This page describes products and general use; it is not medical advice.
A plaster bandage, also called a plaster of Paris bandage, is a roll of gauze-like fabric impregnated with dry calcium sulphate hemihydrate. Dipped in water, it sets into a hard shell used for casts that immobilize a limb and for impression molds. It is used by orthopedic and emergency clinic staff, and it is bought and compared by supply buyers and students of orthopedics.
What a plaster bandage is
Plaster of Paris is calcium sulphate hemihydrate (2CaSO4·H2O), made by heating gypsum (CaSO4·2H2O) at about 120 °C to drive off part of its water. With water it sets into a hard, porous mass (Szostakowski et al., 2017). A plaster bandage carries that powder on a woven roll so it can be wrapped, wetted and molded. Gypsona is one brand name of plaster of Paris bandage; “plaster bandages”, “plaster of Paris bandage” and brand names all describe the same product class.
One manufacturer lists the intended uses of its plaster bandages as casts to immobilize limbs after fractures, operations and orthopedic corrections, and impression molding of a residual limb or foot for orthotic and prosthetic work (Lohmann and Rauscher, Cellona).
How it is built and how it sets
The roll is the dry plaster-loaded fabric. One product described by its manufacturer has a green core with holes that lets water into the roll and a firm core that helps prevent telescoping; each roll is individually sealed, 12 per box, and the product is labelled latex free (Lohmann and Rauscher, Cellona).
Setting is a chemical reaction with water, not drying. Generic plaster of Paris sets within roughly 5-15 minutes and takes much longer to dry completely (Szostakowski et al., 2017). The reaction gives off heat.
Setting and drying times by product
Textbook figures and product claims differ because products are formulated for different speeds. The table keeps the two sourced figures side by side.
| Stage | Generic plaster of Paris (journal review) | One extra-fast-setting product (manufacturer) |
|---|---|---|
| Setting | 5-15 minutes | 2-4 minutes |
| Fully dry | 36-72 hours | 12-24 hours |
Sources: Szostakowski et al. (2017); Lohmann and Rauscher, Cellona product page. Both checked 2026-10-30.
Sizes: one manufacturer’s range
Sizes are given as width by roll length. The table is one manufacturer’s Cellona range, not a universal standard.
| Width x length | REF |
|---|---|
| 2 in x 3 yd | 91380 |
| 3 in x 3 yd | 91381 |
| 4 in x 3 yd | 91382 |
| 5 in x 3 yd | 91383 |
| 6 in x 3 yd | 91384 |
| 8 in x 3 yd | 91385 |
| 4 in x 5 yd | 91162 |
| 5 in x 5 yd | 91163 |
| 6 in x 5 yd | 91164 |
| 8 in x 5 yd | 91165 |
Source: Lohmann and Rauscher USA, Cellona Plaster of Paris Bandages, checked 2026-10-30.
Plaster versus fibreglass
| Property | Plaster | Fibreglass |
|---|---|---|
| Weight and strength | Heavier | Lighter and stronger (described as three times stronger at one-third the weight) |
| Moulding | Allows moulding | Does not allow moulding |
| Swelling | Widely used because it can be applied acutely and moulded | Less accommodating to swelling |
Source: Szostakowski et al. (2017). For the difference between a cast and a splint, see what a splint is; for keeping a cast dry, see shower covers for a cast.
Heat and product differences
Setting is exothermic, and the review reports that faster-setting plasters carry a higher thermal-injury risk (Szostakowski et al., 2017). One manufacturer lists a “very low level” of exothermic reaction as a product feature; that is a product claim, not a general property of plaster. Set times, heat output and sizes vary by product, so the manufacturer’s instructions for use for the specific product are the reference.
Related reading on adjacent support products: buddy tape materials and limits and sports medicine clinic supply checklist.
Frequently asked questions
How long does a plaster bandage take to set?
Generic plaster of Paris sets in about 5-15 minutes (Szostakowski et al., 2017). One extra-fast-setting product lists 2-4 minutes. Full drying takes 36-72 hours for generic plaster and 12-24 hours for that product.
Is a plaster of Paris bandage the same as Gypsona?
Gypsona is a brand name of plaster of Paris bandage, so it belongs to the same product class. Specifications vary by product, so check the manufacturer’s instructions for the one in use.
Why does a plaster bandage get warm?
Setting is an exothermic reaction. The review reports that faster-setting plasters carry a higher thermal-injury risk.
Related supplies
For related items, see emergency, trauma and crisis response supplies.
Sources
- Szostakowski B, Smitham P, Khan WS. “Plaster of Paris – Short History of Casting and Injured Limb Immobilization.” Open Orthopaedics Journal 2017;11:291-296. doi:10.2174/1874325001711010291. https://pmc.ncbi.nlm.nih.gov/articles/PMC5420179. Checked 2026-10-30.
- Lohmann and Rauscher USA. Cellona Plaster of Paris Bandages. https://www.lohmann-rauscher.com/us-en/products/casting-materials/plaster-of-paris/cellona-plaster-of-paris-bandages/. Checked 2026-10-30.
