Top-coat plastering or skim is a challenging DIY task and while it is not a complicated affair to apply plaster on the wall or ceiling, but getting it flat and smooth increases the level of difficulty and that requires patience and practice.
And rightly so, our first step is to practice every aspect of the project before you all out into the plastering process.
It’s really surprising to know just how quickly the top coat plaster hardens. Skimming a surface is all about timing, as getting it done too early or too late can result in a botched up plastering job. As a best practice, it is always recommended to apply two coats of plaster and the second coat should be applied immediately after the first one.
Hence, before you get started on your project, we recommend that you mix a small amount of material as a tester. Next, spread the material on a side of the wall and mark the time it takes to go firm but not hard. This is the time it takes to skim and smoothen the surface and clear the imperfections. Once your skim is hard enough, it can be smoothed finely using a sandpaper.
Hence, spending quality time to practice plastering will take you a long way in getting it right when your project is well underway. Remember, if you get it right, doing your own skim plastering can save you a lot of money. If you get it wrong it can cost you a fortune to correct those errors.
This important part of the plastering process is often overlooked and causes problems as you proceed with the plastering project. In order to get the right consistency, mix the dry plaster with cold water and not the other way around. The dry plaster must be mixed with enough water so you get a creamy paste with no lumps. Ensure you continue to move the mix while adding the plaster in little quantities. You can also use a paddle blade that could ensure a consistent mix.
To start the mixing process –
• Fill cold water into a two-gallon bucket to about one-third of its depth.
• Add the plaster mix gently until it rises over the water.
• Begin mixing slowly. If you’re using a paddle, then at a low speed run the paddle up and down, side to side within the bucket to evenly mix the plaster with the water. Keep an eye on the mix and add water or the plaster mix till you get a cream-like consistency.
Skimming ceilings is like an advanced level in plastering parlance, hence it requires a good deal of practice. Here’s how you start this stage:
• Take a small amount of the plaster mix onto a hawk.
• Tilt the hawk towards you while scooping the skim off the heap using the trowel, in one swift movement.
• Next, evenly apply the plaster onto the wall or ceiling and continue with the rest of the surface. Ensure this is done quickly to avoid the plaster from hardening too much.
Ignore the trowel marks at this stage and do not attempt to smoothen the surface as soon as you have applied the plaster. Ensure that your application is even and matches the required thickness (One coat of 3mm thick or preferably 2 coats of 1.5mm). If you are applying the recommended second coat, it should be done immediately after the first coat.
At this stage, you get to the smoothening process as you notice the plaster just hard enough to remove the trowel marks. If not, a third coat will be necessary. Once you have achieved the desired even thickness of about 3mm, go back to the portion of the surface from where you started plastering and begin Trowelling Up.
As the plaster sets it will darken in color, which means it’s time for the final trowel. While you trowel up, your float will drag plaster from excess or high spots and applies them evenly onto the lower areas. But you can always add more plaster to places where you think the surface is uneven or does not match the required thickness to the other portions of the wall.
The important element to bear in mind when plastering a wall is to work through all of the different stages one at a time and the polishing process gets easier as the plaster dries out. This could save you a lot of time and effort at the final sanding stage.
As we mentioned before that plastering isn’t easy, but Rome wasn’t built in a day either. So, if you choose to not hire professionals for the job and plan to plaster your home or office yourself, pick an extended holiday so that you have enough time at hand to go through each stage of the plastering process patiently and not in a hurry to finish the project.