MastaBlock Joint Compound Siniat

MastaBlock is a pink plaster based setting cement designed specifically for back-blocking ceiling joints in accordance with Australian Standard 2589.1. Back-blocking reinforces the joint, minimises deformation and possible cracking that may occur due to stresses from building movement. MastaBlock has a working time of 3.5 hours and sets in 4 hours allowing plenty of time to complete back-blocking and to maximise use of a single gauge. Great for skillion roofs as ceiling joints can be back-blocked progressively, working from below the board.

MastaBlock mixes easily by hand or electric mixer to a smooth gauge providing a strong bond between back-block and plasterboard lining, strengthening joints and minimising joint distortion and the possibility of cracking. MastaBlock is pink for easy identification.


  • Chemical setting
  • Designed specifically for back-blocking ceiling joints
  • Pink in colour
  • Strengthens joints
  • Minimises joint cracking
  • Long setting time
  • Available in a 20kg bag

Additional Information



Unit Size

20kg Bag


Powder / Dry Compounds (Siniat) – Safety Data Sheet
Plasterboard (Siniat) Installation Instructions
Siniat System (Siniat) Warranty


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