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Product Focus

Plaster of Paris - Usage Advice

Plaster of paris bandages

Algeos' plaster bandages are used in the medical sector, for manufacturing sterile plaster bandages, limb supports, medical prosthesis and hearing aids. In this domain, our plasters are chosen for their excellent quality and grade, and capacity to accurately reproduce limbs, both in shape and dimension.

Bandages are manufactured through a process involves soaking a woven fibre material in a plaster solution, which is subsequently dried. Plaster bandages are fast and practical to use; soaked in water, the moistened bandage is applied to the limb, hardening rapidly, to form a resistant casting, which does not lose shape.

Modelling plasters are used in Orthopaedics as impression and modelling compounds. Limbs are moulded in plaster to serve as a pattern for artificial limbs. Plaster also serves to cast limbs or articulations which will facilitate the fitting of prosthesis.

These excellent plaster bandages offer enhanced mouldability for casts applied in circular turns, for immobilisation after fractures, othopaedic corrections and for treating general joint and bone disorders.

We supply these 'ready to dip' bandages in the following sizes:

3 inch (7.5cm) x 3m
4 inch (10cm) x 3m
6 inch (15cm) x 3m
8 inch (20cm) x 3m
6 inch (15cm) x 25m Slabs


Fine casting plaster (Plaster of paris)

Our Fine Casting Plaster is a hemihydrate plaster (CaSO4.1/2 H2O) produced from naturally occurring gypsum mineral. It is off-white in colour. Our plasters are chosen for their excellent quality and grade, and capacity to accurately reproduce limbs, both in shape and dimension.

Plaster based products are not recommended for conditions where they are likely to be located externally or in any way subjected to weathering or excessive dampness. When stored under dry conditions, this product will have a shelf life of three months from the date of manufacture.

Absorption of moisture can result in changes to physical properties including a reduction in the set strength of plasters and also a lengthening of setting time. To help protect the product during use, open or part used containers should be carefully closed or sealed.

We currently supply Plaster of Paris in 25kg poly tubs. This ensures safe transport and allows for a clean working environment.


Casting sundries

Algeos stock the following sundry products for the plaster room:

  • Bandage scissors
  • Cast shears
  • Electric cast cutters
  • Mixing bowels
  • Stockinette
  • Foot impression boxes
  • Plaster cast shoes
  • Algecast casting foam
  • Rubber latex gloves
  • STS copy socks
  • Cast rectification tools


Best practice guidelines for plaster products

In order to obtain optimal results from our plasters, some basic usage guidelines should be respected. Technical data sheets exist with specific usage instructions for each product.


Plaster to Water ratio

It is important to respect the indicated plaster to water ratio and to accurately weigh the water and plaster. Variations in the plaster to water ratio have a direct influence on product characteristics:

  • Absorption capacity
  • Density
  • Hardness
  • Setting time
  • Sedimentation
  • Expansion
  • Durability
  • Sprinkling

Plaster is always added to water and never the contrary. We recommend using a clean recipient and clean tap water at a constant temperature, for mixing plaster. The plaster should be sprinkled slowly and evenly across the entire surface of the water. The time taken to do this will vary between 1 and 3 minutes depending on the size of the batch. If the plaster is sprinkled too quickly, dense and dry lumps can form that will not disappear during mixing.



The soaking time should vary between 1 and 2 minutes, depending on the size of the batch. Sufficient soaking ensures that each plaster crystal is surrounded by water, and that air bubbles can escape from the mixture. If plaster is not allowed to soak for long enough, air bubbles may remain in the finished plaster mould. Soaking for too long gives rise to a shorter setting time, earlier hardening and a grainy surface.



The mixture should be stirred vigorously with clean utensils which are free from set plaster, to obtain a homogeneous lump-free consistency. The optimum stirring time is dependent on the size of the batch and the dimensions of the stirring device. If plaster is not stirred for long enough it will not be evenly mixed, and if stirred for too long the mixture will become too thick, in both cases this has a negative effect on product characteristics. Longer stirring times generally lead to: greater strength, reduced absorption capacity and shorter setting time. Plaster which is vacuum- mixed has lower absorption capacity, reduced expansion, and increased strength.



Apply a specific lubricant or separating emulsion, in as fine a layer as possible using a brush. Wipe with a cloth afterwards to avoid remnants and structuring. Incorrect or excessive use of lubricants may cause mildew, and lead to problems or defects during drying and lifting.


Drying plaster moulds

Plaster moulds must be carefully dried in order to achieve even and optimum physical characteristics. Ideal drying conditions are: 40-45C and 40% relative humidity. Dryers should record both temperature and relative humidity for effective mould drying.