- Assessment of the work front
- Preparation of the coating and premises for work
- Mixing rules
- How to apply and level the plaster composition
- Differences in work with start and finish
- Final alignment and validation
Instead of hiring a team of plasterers for each repair, you can learn how to putty yourself, save money and be sure of a good result. In this article, we will show you how to level walls with plaster putty, and explain why it only seems such a difficult skill..
Assessment of the work front
Walls plastered with cement mortar can have a total drop in the plane of up to 50 mm and local drops of up to 10 mm per meter. This is unacceptable if you are planning high quality decorative finishes or using materials that require a smooth and durable base..
First, take enough time to examine all surface imperfections. Use a rule or level at least 200 cm long.Applying it to the walls, mark with a construction pencil the boundaries of depressions or bumps, and inside write the approximate value of the difference in millimeters.
Check the verticality of each wall. At the same time, on the floor and ceiling, apply risks that determine the thickness of the leveling layer. Stretch the chopping line with the dye so that it coincides with as many marks as possible and lay a line along them.
Now, knowing the approximate layer thickness and calculating the total surface area, determine the amount of material based on the consumption rate. Please note that even protruding bumps need to be covered with a layer of putty at least 2 mm, and when reinforced with a mesh – at least 4.5 mm.
Preparation of the coating and premises for work
Start leveling the walls only if other work in the room is finished or suspended. Do a thorough cleaning: remove debris and dust, sweep the walls and wipe the floor. Remove unnecessary building materials and tools from the premises.
Moisten the walls with water from a spray bottle, after 15–20 minutes apply the deeply penetrating primer with a brush-brush, as abundantly as you can. Using a brush will pick up loose sand from the wall and make the surface more durable, so do not use a roller. The deep penetrating primer should be applied in several coats, the quality of the impregnation is easy to check: dip the brush into the primer and squeeze it against the wall. If the drip length is less than 2 meters, apply another layer. After impregnating the wall with a primer, it is recommended to apply another layer of highly adhesive compound..
For further work, you will need a high table or stepladder and a new plastic mixing bucket. Of the tools you will use: a wide spatula of at least 450 mm, a 120 mm spatula and a rectangular trowel, a sponge trowel and an abrasive mesh. Keep a few skeins of Serpyanka handy.
The mixture should be prepared only in a clean bucket, the presence of remnants of the old composition accelerates hydration and hardening by 30–40%. Get in the habit of cleaning the bucket immediately after mixing, and the tools and mixer immediately after use. Wash off the putty with a conveniently used abrasive mesh.
Pour the correct amount of water into the bucket according to the cooking rate. If in doubt, pour 3 times less than the volume of the finished composition you need. Putting dry putty on the trowel, add twice as much powder as the water poured. First stir the mixture several times with a mixer to make the solution wet, then mix at medium speed for 1.5-2 minutes.
Adjust the thickness of the compound by adding dry putty or water. When a small amount is collected on a trowel, the composition should not spread by itself. Mix the putty at low speed for another 2-3 minutes until a completely homogeneous mass is obtained. Leave the putty to stand for 5 minutes and stir again, then start working. The life of a properly prepared mixture is no more than 60 minutes. Do not whisk the putty at high speed and do not cook less than 3 kg in terms of dry mixture, all this increases the hardening speed by 4-5 times.
How to apply and level the plaster composition
Spread a small amount of the mixture over the edge of a wide spatula and spread it as evenly as possible along the entire length. Holding the trowel with both hands, place it against the wall and press firmly until a small amount of putty emerges from under the edge. With an even motion, pull the spatula with the handle forward, thus spreading up to 2/3 of the composition. Use a narrow spatula to pick up the remaining mixture from the edge and stretch it again along the edge. Apply the composition crosswise to the previous stroke. Using a cleaned trowel, level the composition in different directions from the center.
When leveling and applying the composition, the angle between the trowel and the wall plays an important role. The smaller it is, the more composition you apply and the less you remove when leveling. When setting the trowel at an angle of more than 45 °, you will leave a lot of scratches, but you will be able to pull off a thicker layer.
Begin to apply the composition to the wall from vertical and horizontal corners, adjusting the layer of the composition along the skipping. Then put putty on the grooves in the plane of the wall. Let the first layer dry and again examine the wall with the rule, mark the unevenness. Remove strongly protruding furrows with a dry spatula.
With a second layer, remove the remaining irregularities and smooth out the composition, leaving as few stripes as possible. Smooth out irregularities with a trowel with an abrasive mesh and apply a third even layer over the entire surface of the wall, carefully leveling the composition with a trowel.
Differences in work with start and finish
The finishing putty creates a hard, smooth and perfectly flat surface on the wall for laying tiles, subsequent painting, or, for example, marbled finish. The optimum layer thickness is 2–3 mm, for leveling it is allowed to apply to areas up to 5 mm of the composition. After applying the first layer of the finish, a serpyanka mesh is laid in the corners and stretched with a spatula.
For preliminary leveling of the walls, a starting putty is used. Its composition is more grainy and malleable, which makes it possible to apply it with a wide tool and even a lighthouse rule. The starting putty has a lower hardness and reacts better to the shrinkage of the building, serves as a damper pad between the bearing surface and the finishing layer.
A layer of starting filler is reinforced with a fiberglass mesh, laid on a freshly applied compound and pressed with a spatula. After the first layer has dried, the remnants of the mesh must be cut off and the surface level with the second. The perforated profile is also applied to a thin layer of “start”, then the angle is leveled with a wide spatula along the edge.
Final alignment and validation
If the highest quality of preparation of the coating is required, the finishing filler is applied in several thin layers using a wide trowel. After drying, the surface is treated with light movements with a grater with a grid of 120 grit, or rubbed with a damp sponge the next day after application. Then primed and apply the next layer.
The finishing layer of the finish must be checked for evenness with a building level, then treated with a 180 grit mesh and covered with a penetrating primer. Pay special attention to all the inner corners, where irregularities can most often be found. Curves in the corners must be leveled, otherwise wallpapering and installing baseboards will be of poor quality.