Before starting this job clear the room of furniture and any expensive electrical equipment. The job is messy and the materials used could easily cause damage which could result in a claim on household insurance.
Spread plenty of plastic sheets all over the floor of the room. Mix your plaster according to the instructions on the bag, remembering to always add the plaster to the water using a clean bucket. It is vital to mix the water and plaster thoroughly so that the ready plaster will have a thickish, creamy consistency with no lumps. During the warmer months, the plaster can set within minutes, so it is a good idea if you are a novice to only mix an amount that can be used straight away. Another good tip is never add any new plaster to an old mix and do not add extra water to the plaster in an effort to make it more workable.
When the mix is ready, get a trowel full of plaster from the mix and onto the hawk, and then transfer about half the plaster to the trowel. Try to keep the wrist as straight as possible and use a flicking action with the hand holding the hawk to move the plaster from the hawk to the trowel.
Starting at the bottom of the wall, try and use smooth strokes to press the plaster onto the wall. Slowly close the gap between the top edge of the trowel and the wall when moving the tool upwards. Keep the trowel at a slight angle to the wall at the end of each stroke. If the trowel is flat against the wall surface it could easily pull the new plaster away from the wall.
Go over the entire area with the aim of applying a base coat, uneven areas or holes are not important at this point. The coat should be around 2mm thick. Next job is to level and smooth the surface, but only do this when the plaster has hardened slightly. Waiting for the plaster to go off can vary from a couple of minutes during the summer to twenty minutes or more in cold conditions.
Use the trowel at a shallow angle to the wall and go over the entire surface smoothing it out. Leave the plaster to dry for around forty minutes. When it is dry it can be polished. Do this by wetting the face of the trowel and flick water onto the wall. The idea of this is to provide just enough lubrication for the trowel to glide over the surface and fill out any small holes and imperfections. Use sweeping strokes to start and finish with long continuous strokes across the wall. When happy with the finished effect, wash all the tools immediately ready for future use.