Step 1

The technique for applying finishing plaster is the same whether you skim over drywall sheets (as here), render, or undercoat plaster, though the surface preparation varies. An undercoat should be slightly damp when plaster is applied; use a mister to dampen it, if necessary. Practice using plastering techniques on a small area before tackling a whole wall.
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Step 2

Covering board graphic

Covering board graphic

©2007 Dorling Kindersley Limited

2007 Dorling Kindersley Limited

Tip: Covering Board

Drywall can be skimmed with plaster to make the surface suitable for painting or papering. Use tape to cover the joints between boards. Apply a layer of plaster across the entire surface. Then follow the steps below to achieve a smooth surface. The same type of plaster should be used for each layer.

Step 3

Smooth Drywall Joints

Use drywall tape to cover joints between drywall sheets, attaching it with a little prepared plaster (Image 1)

Trim tape with scissors to get a neat edge. Fill any gaps greater than 1/8 inch with pre-mixed plaster (Image 2).

Step 4

Prepare Plaster

Half-fill a bucket with clean tap water, and slowly add the plaster, carefully following the manufacturer's instructions. Mix more as you need it (Image 1).

Use a power stirrer to mix the plaster. Submerge the stirrer before starting the drill and use at a low speed. You can also mix manually (Image 2).

Keep adding plaster and mix until it has a creamy consistency. Run a trowel around the edge of the bucket to incorporate all the dry plaster (Image 3).

Pour the plaster onto a board. It should be thick enough to spread evenly over the board without running over the edge (Image 4).

Step 5

Apply the Plaster

Use a trowel to cut away a section of the mixed plaster, and transfer it to a hawk. Use a small amount at first to get used to handling the hawk (Image 1).

Holding the hawk in front of the wall, cut away a section of plaster, using the plastering trowel. Push the plaster up and onto the wall surface (Image 2).

Spread the plaster across the wall surface, pressing firmly and distributing it as evenly as possible. Work from the top of the wall to the bottom, in broad, vertical and horizontal strokes. Aim to work quickly to cover the surface before the plaster starts to dry (Image 3).

Continue to add more plaster, building up a rhythm of loading the hawk and transferring the plaster to the wall surface (Image 4).

Step 6

Smooth the Plaster

Once the surface is covered, go back over it, smoothing the plaster to an even thickness. Do not try to achieve perfect smoothness yet (Image 1).

Leave the plaster to dry for another half hour, until it is harder, but still slightly damp (Image 2).

Sweep a clean, dampened trowel blade across the entire surface, smoothing the plaster and redistributing any excess to fill small indents. Hold the blade at a slight angle with only one edge on the plaster to achieve a smooth finish (Image 3).

Leave the plaster to dry for at least half an hour, until the surface is firm enough to touch without moving the plaster, but is still damp. Repeat the smoothing process, again using any excess surface plaster to fill small depressions. If necessary, use a wet brush or garden spray gun to dampen the plaster as you work. Aim for a smooth finish at this final stage; it is more effective than trying to sand rough plaster when dry (Image 4).

Use a small, damp brush to finish edges and corners neatly (Image 5).

Step 7

Finish an Outside Corner

To produce a sharp, straight edge when plastering an outside corner on drywall, use a corner bead. This acts as a guide for the finishing plaster, but is covered by the plaster to give a clean finish. Saw the corner bead to the length you need using a junior hacksaw or tin snips (Image 1).

Attach the bead to both walls at the corner ensuring that the bead is tight against the corner (Image 2).

Apply plaster over the top of the corner bead, allowing the plastering trowel to rest on the apex of the bead to give you a good finish (Image 3).

Step 8

Tip: Applying a Second Layer

An alternative to smoothing off the first layer of plaster is to apply a second, thinner layer, giving two topcoats. If you want to follow this option, do it after smoothing the plaster for the first time, before allowing it to dry. Most professional plasterers do this to achieve the flattest, highest-quality finish. Once the second layer has been added, continue the step titled Smooth the Plaster from Image 2 onward.

Step 9

Second Thinner Layer of Plaster for Quality Finish

Second Thinner Layer of Plaster for Quality Finish

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Tip: Finishing an External Corner

An alternative to using a corner bead on an external corner is to smooth the plaster with a corner trowel. This gives a more rustic finish, rather than a clean, straight line. A corner trowel is not suitable for achieving a high-quality finish; corner beads give better results. A similar finish is achieved on an internal corner by using an internal corner trowel.