Thistle Undercoat Plaster Installation Instructions

Our guidance below shows the recommended way to apply Thistle BondingCoat. All times stated are approximate.

Thistle Undercoat plaster comes in handy smaller sized bags, and is perfect for repairing deep damage to walls.

Installation Guidance

0 mins

  • Add approx. 7.5 litres of clean water per 12.5kg bag to mixing bucket. Gradually add the plaster whilst mixing. Avoid excessive mechanical mixing
  • Apply layer 11mm (8mm on plasterboard & ceilings)

40 - 60 mins

  • Flatten off with appropriate tool for the size of the job (i.e. trowel or rule)


110 - 130 mins

  • Key surface by rubbing up with a devil float as the plaster firms up in preparation for finish coat application
  • Product is generally set around 200 mins dependent on background suction
  • Finish with a Thistle or ThistlePro finishing plaster

Times and processes are given as guidance. On site practice may vary. Finishing times are reduced by suction and extended by cold weather conditions.

Note: Thicknesses in excess of 11mm should be built up in a series of 8mm fully keyed coats (subject to background suitability). A new mix of plaster should be used for each new layer which can be applied after the previous coat has firmed up.

For certain backgrounds: Apply Thistle Bond-it before plastering (see Plaster Selector Guide for details on exact substrates).