Before beginning any plastering work it is important to understand what ‘suction’ is and why it is important in plastering. When plasterers use the term ‘suction’ they are referring to the absorption power of the wall. If a wall is ‘high suction’ it will absorb a lot of moisture, and quickly. High suction walls need to be dampened before the application of plaster. If you apply plaster directly onto a high suction wall, it will drink up the moisture content of the plaster faster than the plasterer can flatten it, resulting in a dry, crumbly mess! Plasterers use various techniques to dampen high suction walls.
Depending on how porous a wall is, it may require more or less saturation. In some cases, the wall may need to be damped with a sponge, in others a more forceful method may be required such as a hose. Contrary to high suction walls ‘low suction’ walls present different concerns. If a wall is too low suction, plaster will not adhere to it and therefore require the use of a bonding agent to help it stick.
To find out if a wall is low or high suction, you will need to test a small amount of plaster on a section of the wall. Make sure the room is not too hot as this can affect the drying time of the plaster. If the plaster has dried after a couple of minutes it is likely you have a high suction wall.
The correct plaster is key to a professional looking finish. While many plasters are suitable for multi use applications, plaster is not a ‘one mix suits all’, so you will still need to check you are using the correct formulation for the intended purpose. If you’re ordering plaster online, the product description should explain what applications the plaster is suitable for. If you’re buying from a DIY shop, ask a salesperson for advice, they should be happy to advise you in the right direction.
If you want to achieve a smooth, and more importantly, level plaster finish you’ll need the right equipment to help you. The trowel is perhaps the most important tool when plastering. It is used to apply and smooth the plaster. Smaller trowels tend to be easier to manage, especially if you are new to plastering. While there is some concern that smaller trowels will leave marks in the plaster, longer trowels require more skill to handle and can make it especially hard to achieve an even surface.
Next on the tools list is a plastering hawk. This is the square shaped sheet with a stick shaped handle. Plasterers use Hawks to hold plaster as they work. This tool isn’t absolutely necessary, but it is rare you will see a professional plasterer without one.
As with any DIY job, the use of a hawk and trowel requires skill and technique. Watch some demonstration videos on how the professionals do it. Then, practice your technique on a dummy wall (a sheet of plywood) until you feel confident enough to try it in your home.
Plastering hawks are found in various materials. The best type for beginner use is a foam hawk. Foam hawks don’t weigh very much and so are perfect if you’re not used to manual work (plastering can really take its toll on your arm muscles). Foam hawks are also pretty cheap and therefore can be replaced easily once they become worn.
When mixing your plaster you may find it easier to use a plaster mixing tool. Plaster mixers are designed to take the strain out of plaster mixing. Think of it as the plasterer’s version of an electric cake whisk. If you know you have a lot of area to cover and plan on doing more plastering in future, it may be a good idea to invest in your own plaster mixer. Otherwise, you may just want to rent/borrow a mixer from a local company or someone you know.
Other Plastering Tools
Other tools which are essential for plastering are:
- Jointing knife
- Plaster mixing bucket
- Sponge/water brush
- Plaster bucket cleaning brush
Now you know a little bit more about plastering, you may feel confident enough to give it a go. Remember, all it takes to achieve a professional plaster finish is patience and practice… lots of practice that is!