How to skim plasterboard

Summary: Learn how to skim plasterboard, mix plaster, skim with plaster, use a hawk and float, apply plaster to a wall, apply a second coat of plaster to a wall and polish plaster.

Plastering requires a high level of skill and can only be acquired over a long period of practice. However, there is no reason why a novice cannot learn how to plaster by starting on small jobs, moving on to plastering larger areas as his or her skills and confidence develop. Here we are looking at skimming plasterboard assuming the joints have already been sealed as covered in Fixing plasterboard to a stud wall.

Mixing plaster

Skimming plaster is bought in bags which will have the mixing instructions printed on the bag. But generally the mixing method is as follows:

  • Place a spot board on a firm support that brings it to about waist height. This is the best height for loading the hawk.
  • Fill a plastic bucket with water up to about a third of its capacity.
  • Start adding the plaster from the bag, or scoop it from the bag and add to the water. Do not add too much plaster in one go. Add 3 or 4 scoops to the water and then mix it using a piece of batten. This method of mixing avoids lumps of plaster forming.
  • Keep adding plaster and mixing until you have a smooth, creamy consistency.
  • With the plaster mixed to the right consistency pour and scrape the contents of the bucket onto the spot board.

Loading the hawk and float

  • Holding the hawk in one hand and a plaster’s trowel in your dominant hand, load an amount of plaster onto the centre of the hawk with the float.
  • Keeping the hawk at just above chest level, practice loading the plaster’s trowel from the hawk. It is a good idea to remain at the spot board while practicing to avoid dropping the plaster on the floor.
  • With the blade of the trowel held at a right-angle to the bed of the hawk, push a small amount of plaster to the edge of the hawk furthest from your body. While carrying this out, slightly tilt the hawk towards your body and as the hawk tilts produce a scooping action with the trowel. This must be done in one fluid movement. Begin slowly and you will soon master this technique.

Applying the first coat of plaster

  • At one end of the plasterboard wall apply the plaster with the trowel starting at floor level, moving up in a sweeping action and stopping just before you reach the ceiling. The trowel should be held against the plasterboard at an angle of about 30°. Apply the plaster about 33mm thick.
  • At the corner where the wall meets the ceiling apply plaster to the plasterboard in a downward action to meet the plaster applied in the upward sweep.
  • Continue plastering in this fashion until you have covered the wall evenly. But remember at this stage you do not want to cover the taped joints.

Applying the second coat of plaster

  • When the first coat has been applied it needs to be left to dry a little. If plastering a wall with a large surface area, you may find the first coat has dried sufficiently at your starting point to begin applying the second coat immediately.
  • Apply the second coat by beginning at the bottom corner of the wall. Apply the plaster to the wall with a long, fluid sweeping action, beginning each sweep at the bottom corner of the wall.
  • In this fashion, work along the wall until it is covered in an even coat of plaster. This time covering the taped joints.
  • Clean your trowel thoroughly and when the second coat has dried a little, glide the trowel over the wall to remove any marks or ridges. At this stage ensure the plaster is smooth and even in the corners and where the wall meets the floor, ceiling and adjacent walls.

Polishing plaster

  • When the plaster has hardened it needs to be polished. Clean your trowel thoroughly once again. Then after splashing water onto the surface of the wall using a plasterer’s brush (or large paint brush), run the trowel over the surface of the wall.
  • The water allows the trowel to pick up a film of plaster, which fills any minute holes or uneven areas. It is important to remember not to apply too much water, as the wall only needs to be moistened – not saturated.
  • The newly plastered wall must be left to dry out thoroughly before any decorating is carried out. How long this takes will vary on the size of the wall and the time of year, but the plaster will turn a lighter colour as it dries.

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