Plastering and Skimming Coats

Both plasters and skim coats are used to improve the appearance and quality of wall surfaces.

Plasters

Plasters are coarse mortar, applied directly onto substrates like concrete, brick or block walls to a thickness more than 5 mm to create a level surface. Also used as a base layer before skim coat.

Skim Coats

Skim coats are fine mortars applied onto walls and ceilings to a thickness of 2–5 mm to create a flat, smooth and uniform surface, to be painted or re-textured.  

Skim coats are fine mortars applied onto walls and ceilings to a thickness of 2–5 mm to create a flat, smooth and uniform surface, to be painted or re-textured. As a guide, you should apply at least two skim coat layers to achieve a smooth and consistent surface.

The number of layers may differ, depending on the final optical appearance required.

1. Substrate – concrete or masonry/brick wall
2. Preparation of substrate – concrete repair, crack filler, primer
3. Thick layer for first levelling e.g. masonry – plastering
4. Thin layer(s) for smoothing – plastering, skim coat
5. Final coatings – post-treatment, paint, wallpaper, tiling

One of the main differences between general plastering and a skim coat is the thickness of the coating. Skim coats are typically thinner (applied to a thickness of up to 5mm), while general plaster can be applied to a thickness of anywhere from 5mm to 30mm.

What’s the difference between plastering and skimming? 

The term plastering is typically used as the general reference for the trade and activities related to preparing and coating the internal walls and/or ceilings of a building. 

There are various types of plastering techniques, and skimming is one of those. Another common difference in using the terms plastering vs skimming is that many people refer to plastering when it’s a new wall or ceiling, while skimming is often used to describe freshening up an existing/old wall or ceiling. 

When is plastering skimming? Skimming specifically refers to the process of applying a thin layer of finishing plaster to create a smooth finish for the surface of walls or ceilings, usually so that it’s ready for painting or covering with wallpaper. In the stages of plastering a wall or ceiling, skimming is generally considered to be the final stage. 

What is plastering vs skim coat? A skim coat refers to the layer lime that is applied over rough cement, which may then be smoothed out using various plastering techniques. One of the main differences between general plastering and a skim coat is the thickness of the coating. Skim coats are typically thinner (applied to a thickness of up to 5mm), while general plaster can be applied to a thickness of anywhere from 5mm to 30mm.

Leave it to Men@WorX who understand how to work in a slow, systematic and neat fashion. Men@WorX uses a step by step guide to plastering, and we will take you through everything you need to know, and with a beautifully finished plastered, and skimmed wall, or ceiling. 

First things first, Men@WorX has the adequate tools and materials for the job.  

Tools and Materials

It’s always a good idea to be prepared for wall plastering well in advance.  The tools and materials we have to complete the job include a trowel and bucket trowel, plasterers float, corner trowel, hawk board, two buckets, mixing stick or a paddle, adequate plaster, PVA, dust sheets', clean water, sandpaper, stepladder or stilts, and a dust mask.

Step 1: Preparation 

Before Men@WorX begins working on the walls, or ceiling we make sure to lay down a dust sheet to protect your floors and gather any potential debris or spillage of plaster. Men@WorX will ensure that the wall, or ceiling you want to plaster is dust-free and we get rid of the debris, as this is particularly important if we are plastering an older and worn-out wall. Men@WorX will cover any holes and cracks we may find in the wall, or ceiling using screen tape. In case we are plastering over newly erected plasterboards, we use the screen tape to mask all the joints in between the boards.

Step 2: Apply PVA To the Wall, and Ceiling

Being a latex-base product, we use a similar to glue that seals the pores of the drywall, applying PVA to the walls, and ceilings we are about to plaster will ensure that the layer we will use will dry out equally. First, we to dilute the PVA in a 1:4 ratio – one-part PVA and four parts water. We roll the PVA mixture onto a brush, applying it onto the wall, or ceiling, and check that that the entire surface is covered. Once we go over the wall with the PVA glue, the first plaster layer can be applied.

Step 3: Mix the Plaster 

Depending on what type of plaster we will use for the project, we use the manufacturer’s manual, and mix it accordingly. We wear dust masks as we open up the bags of the material. Men@WorX will pour it into a bucket of cold water and whisk briefly until it has the consistency of thick custard with no lumps.  We continuously mix the plaster into the water.

Step 4: Apply Plaster onto The Walls or Ceilings

Once we got the walls, or ceilings cleaned, and the plaster mixture is ready, we start applying the first coat of plaster using the hawk board, the trowels, and a floating tool. 

Men@WorX places the plaster on the hawk board using the trowel and we use the float to push the material from the hawk onto the walls, or ceilings. We spread the plaster firmly upwards and flatten the float at the end of each sweep. We apply the plaster from the bottom left-hand corner and upwards, filling a whole section from bottom to top before moving on to the next section. We use small amounts of plaster combined with a firm pressure on the float, so we ensure a smooth look and avoid excess plaster coming off the wall, or ceiling in which we replicate this movement until the entire surface is covered with plaster.

Step 5: Skim and Smooth

Right after the first coat of plaster is applied, we wait for 20 minutes to allow the plaster to dry. Afterward, we get rid of bumps and lumps by smoothing the wall over with a trowel. We smooth out the corners with the corner trowel and the bottom and top of the wall, and ceiling too. These are the trickiest areas to plaster correctly, so we use adequate tools to even the edges out.  

Step 6: Scrape 

Scraping is optional, but Men@WorX prefers to scrape the wall, or ceiling before adding the second coat of plaster for the second coat to adhere properly. The simplest way to scrape the wall is by using a devilling float, a tool specifically designed for 

Step 7: Second Coat

Men@WorX applies the second and final coat of plaster to the walls, or ceilings. This one will be of a thinner consistency than the first one, which we dilute the plaster mixture with some more water. We plaster a thin 2 mm layer on the wall, or ceiling, and we leave the material to slightly dry.

Step 8: Finishing Touches 

Once the plaster is slightly dried, we polish our work. We add some water to the walls, or ceilings using a spray gun. Men@WorX makes sure to spray the edges of the plaster and we use a trowel to smoothen out the surface with inward strokes. We finish it off by running a clean float over the entire wall, or ceiling to flatten out any curves and bumps. When the plaster is completely dried, we use some sanding paper to remove any excess material.

Step 9: Painting and Wallpapering 

Your walls, and ceilings are now ready to be painted over or wallpapered if that’s what you prefer. Men@WorX uses an undercoat to prime the surface before we apply paint. The same goes if we’re about to hang wallpaper, even though it may be best to use a wallpaper adhesive instead. We ensure to apply two coats of adhesive to prime and seal the surface.

Final Words 

Plastering & Skimming with Men@WorX – We get it done!

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Email : [email protected] Visit us on www.men-at-worx.co.za 

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