How to Apply Finish or Skim Coat
How to Apply the finish coat with six stages.....
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. You move from one stage to the next once the plaster has firmed up and gone tacky. Many beginners try and do too much too soon and are 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 then this does not necessarily mean there is anything wrong with your technique but probably 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 do do always remind yourself of the objective of each stage.
The plaster can firm up for two different reasons either:
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 suction test should always be carried out. If you are applying the skim coat on plasterboard then you need not worry as the suction is controlled for you with the paper.
In some instances if the backing coat is very porous the moisture can be sucked out almost instantly. This is definitely not good as by the time you have finished applying plaster to the whole wall, the first application will be totally dry and therefore firm which will make it very difficult if not impossible to carry out the next stages.
Apply 1st coat of finish plaster approx 2mm thick
Aim – flat even coat that is not bulging. Trowel marks and ridges no problem
How – Gradually flattening trowel loaded with plaster.
Download the Step by Step Guide with details on all stages.