How to Skim
An Overview of the skimming process.
Learning how to skim? There is an important step first wall preparation (in Index).
The Finish Coat
The skim (finish) coat is the final coat and is responsible for smoothness. It is not designed to flatten so the background to which it is being applied must be flat – if not it can be near impossible to remove trowel marks.
Not only this but an uneven background can result in some areas having a greater thickness of plaster. The firming up process is influenced by the thickness of plaster. When the plaster begins to firm up - it behaves differently so whilst cannot be flattened so easily - holes and hollow areas can be filled and trowel marks removed.
Therefore if one part of the wall is twice as thick as another, it could take twice as long for it to firm up, which means it cannot be finished like the areas that are becoming firm. This is inconvenient if confined to one edge of the wall but if there are several areas like this then it can result in an inconsistent and sub standard finish.
The importance of a flat backing coat can't be underestimated.
An understanding of all the stages of skimming is essential in achieving a nice flat and smooth finish. It is not just a case of applying the plaster and immediately smoothing it out: if you feel you are going round in circles, solving one problem but creating another, there's a chance it is too wet. Walking away from the wall and allowing it firm up a bit before you try and complete the next stage may be all that is needed!
There are 6 stages of skimming to complete - once you know what you are aiming for at each different stage, and how to carry this objective out, skimming becomes much easier - honest!
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