Plastering techniques

There are some beliefs that surround traditional plastering. And since many of the methods used in traditional plastering are all but obsolete, it is easy to consider many observations regarding the craft as standard practices.

Better understanding the materials, using traditional tools and minute examination of the original installations are the keys in unlearning many wrong presumptions and proper repair of priceless plasterworks.

1.      Mixture proportions. According to the popular belief, ideal proportions should be one part lime to three parts of pit sand for initial coats and equal ratios of lime and silver sand for final coats.

It takes some practice to achieve a flat and smooth surface that plasterers always aim for. Basic insights and experience on plastering should be able to equip you with the knowledge on proper preparation, tools and most importantly the adhesion of the plaster.

It is essential to master the basic skills and techniques in plaster application in order to achieve the expected output.

Handling the Plaster:

A trowel full of plaster would be enough when starting out. Place the plaster on the surface of the hawk. The hawk should be carried towards your body and not away from it. Scrape half of the plaster from the hawk using a trowel. While lifting the plaster up, the trowel should be oriented horizontally to avoid spoilage of the plaster.

Cracks, holes, bulges and detachment from the laths are some of the common problems with plaster installations.

These problems can emerge during the progressing plaster job or later in the succeeding years. Though these problems can be easily repaired, addressing the causes of plaster failure can save the plaster from further damage and can be very helpful in preventing such problems to reoccur.

1.      Structural Failure

•  Overloading. Load-bearing walls are prone to stress cracks. The stress imposed on beams, joists and studs might be greater than expected. This can be caused by renovations in some areas of house (e.g. cutting-in a door or window) wherein installation of additional load-bearing support was not considered resulting in additional stress directed to the walls.

General Types of Plaster:

Gypsum Plaster – This type of plaster is wildly known as plaster of Paris because of a  large gypsum deposit in Montmartre, Paris.

Gypsum plaster is produced by mixing water with calcium sulphate hemihydrate, a by-product of heating gypsum to about  300⁰ F.

Gypsum plaster was popularly used before to mimic the surfaces of  wood, stone and metal.

Lime Plaster – Is a mixture of calcium hydroxide (commonly known as slaked lime) and  sand. Limestone is the raw ingredient of lime plaster. Limestone is first heated to produce quicklime and added with water to form the slaked lime. Slaked lime is distributed as a white powder or in airtight containers that prevent the wet lime from settling. Before it could be utilized, water would be added to give the lime paste the right consistency  Lime plaster is commonly used for wall surfaces through the process known as lath and plaster.

Plastering is perfected through the mastery of application. It is a skill that can be acquired through experience and proper training.

To master plastering techniques, one should take into consideration the tools that are essential in the process of plastering. Proper usage of each tool eases the application of plaster and ensures positive outcome if properly handled.

Mixing Tools:

Mixing Bucket – a must in mixing plaster and drywall adhesive. It should be noted that the bucket kept clean. The cleanliness of the bucket affects the performance of the plaster.

Mixer Drill – Manual stirring and mixing tools can be utilized like a piece of wood or  steel but for fast and accurate mixing, a mixer drill is recommended. Mixer  drills are high powered (runs in 1050 watts) and has a paddle attachment   for ease in mixing.