Plastering Guide (Sample)
Trowel technique
Only the trowel is used to apply and finish the skim coat. There is no magic to skimming – it is the combination of firm pressure combined with the correct angle of your trowel (how far the leading edge is from the wall)
Initially when your trowel is loaded with plaster, the leading edge of the trowel will be a long way from the wall. As this amount plaster reduces the leading edge will need to gradually be flattened into the wall. When there is no plaster on the trowel and it is being used for flattening, the leading edge will be approximately 10 – 15mm away from the wall.
Six stages of skimming
Skimming is definitely not a case of applying the plaster and smoothing out immediately – there are many situations that can only be resolved in the later stages.
It is also not a case of just moving from one stage to the next. Progression through the stages is determined by how quickly the plaster starts to firm up.
Beginners have a tendency to try and do too much too soon, often surprised at just how much can be achieved when the plaster is quite firm.
If at any stage you do not see any improvement, this does not necessarily mean there is anything wrong with your technique, but possibly that the plaster is too wet.
In the early stages the objective is flatness - not smoothness. The smoothness will come later – but only if you have achieved flatness, so always remind yourself of the objective (section 3) of each stage.
Plaster staying workable
The plaster can firm up for two different reasons either:
• due to the natural setting process
• or due the moisture being sucked out of the plaster by the backing coat.
The single most important aspect to be aware of is suction.
If you don't have it under control then no matter how good your skimming technique is, you will never be able to achieve a good finish! The plaster will firm up too quickly, and can be so quick, that it prevents an even finish coat from being applied.
Controlling the Suction....