Traditional Lime Plastering, sometimes called Three Coat Lime work is the process of applying and finishing three (sometimes four) layers of lime plaster at different stages in the plastering process. Each 'layer' of Lime Plaster is referred to as a 'coat.'

The first stage of lime plastering is commonly referred to as 'dubbing out.' This is the stage where large holes and any deeper undulations in the wall are packed with plaster, to create a somewhat level playing field ready to receive the scratch coat. These small areas then left to firm up sufficiently before applying the scratch coat. 

The scratch coat is the first coat of lime plaster over the area. This is designed to rough over the wall's initial surface and take up any suction of the substrate. Once applied, it is scratched diagonally in both directions with a scarifier tool or traditionally, some lathe! This leaves an excellent key for the next coat of plaster.

The scratch coat is then left to carbonate before the application of the next coat, which is usually a minimum of a week, but varying conditions mean this can take longer. Cracking commonly occurs in this coat, however it is nothing to worry about as long as the Lime Plasters bond to the substrate remains intact. Commonly in days gone by, this coat was nicknamed the "cracking coat."

During the 'float coat', which is the second layer of lime plaster, the wall really starts to take shape. In particular this coat allows you to get your wall flatter. This is applied in the same way that the scratch coat is applied, via trowel and it is usually the same thickness as the scratch coat.

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Once it has firmed up sufficiently, the float coat is 'rubbed up' with a traditional wooden float. This process is hard work, but allows the lime plaster to be compacted and compressed into the scratch coat, creating a good bond. This process can normally be completed on the same day, but it is not uncommon for it to take a couple of days before being ready to float. A 'devil float' is used at the end of this process to leave a key for the fine finishing plaster.

The fine finishing coat is the final layer of plaster applied to the wall. It is a much finer mix of lime putty and finer sand. This is applied in two consecutive coats and can be finished in a variety of ways depending on the desired outcome. Most commonly found in older cottages or on 'wonky' walls is a sponge finish for the lime plaster, whereas stately homes often had a trowelled or floated fine finish. Examples of various finishes can be discussed before any work is undertaken.