title: Effect of cotton padding on the setting properties of plaster slabs.
abstract: BACKGROUND
  Plaster of Paris (PoP) impregnated bandages have been used to maintain the position of bones and joints for over a century. Classically, wool dressing is applied to the limb before the PoP, which can then be moulded to the desired shape. A modification of this practice is to wrap the PoP bandages circumferentially in cotton before wetting and applying to the patient in an attempt to reduce inhalation of plaster dust and reduce mess. However, this may affect the water content of the cast and therefore also its setting properties and strength. This study compared the setting properties of PoP casts when used with and without cotton wrapping.
  
  
  METHODS
  Sixty specimens, compliant with the American Society for Testing and Materials standards for three-point bending tests, were prepared, with thirty wrapped in cotton. All were weighed before and after water immersion, and wrapped around a plastic cylinder to mimic limb application. Bending stiffness and yield strength was measured on a servohydraulic materials testing machine at 2, 6, 12, 24, 48 and 72 hours.
  
  
  RESULTS
  The water content of cotton-wrapped plaster was significantly higher (50%) than that of standard plaster. It had significantly lower strength up to 24 hours and significantly lower stiffness up to 72 hours.
  
  
  CONCLUSIONS
  The initial decrease in strength and stiffness of the cast wrapped in cotton may comprise the ability of the backslab to hold the joint or bone in an optimal position. Any modification of the standard plaster slab application technique should allow for the potential adverse effects on the plaster setting properties.
authors.affiliation: Robert Jones and Agnes Hunt Orthopaedic Hospital NHS Foundation Trust, UK. daveybarlow@hotmail.com
authors.forename: D
authors.initials: D
authors.lastname: Barlow
authors.forename: R
authors.initials: R
authors.lastname: Bansal
authors.forename: T
authors.initials: T
authors.lastname: Barlow
authors.forename: S J
authors.initials: SJ
authors.lastname: Rhee
authors.forename: J H
authors.initials: JH
authors.lastname: Kuiper
authors.forename: N K
authors.initials: NK
authors.lastname: Makwana
mesh_terms: D001458:Bandages; D002133:Calcium Sulfate / Q000737:chemistry*; D002370:Casts, Surgical / Q000592:standards*; D032561:Cotton Fiber; D006244:Hardness; D018583:Pliability; D013997:Time Factors; D014867:Water / Q000032:analysis
chemical_list: D014867:Water; D002133:Calcium Sulfate