How to SkimLearning how to skim? There is an important step first wall preparation.
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. Progression through all the stages of skimming is in turn influenced by the firming up process. 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 twice as long to complete. 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. 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 of 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. 
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