Lime is a versatile building material with a wide range of applications. Main application in construction: plastering walls with lime mortar. The advantage of this material lies in its high adhesion (adhesion) to any surfaces. The composition equally adheres to concrete, brick and wooden surfaces, forming a refractory and antibacterial layer. The lime layer performs the function of heat and vapor barrier, while it does not crack during finishing work. The only disadvantage of such plaster is the dependence on the level of humidity in the room, therefore it is better not to use lime mortar for finishing bathrooms, or to provide it with additional protection by introducing cement into the composition. Consider how to properly prepare the mixture, and tell you in detail about the application process.
Varieties
There are several recipes for making lime plaster. The difference between the compositions lies in the use of additional components that act as a filler and plasticizer. For interior decoration of premises, the following materials are added to the lime mortar:
- Cement. If you make a solution of lime with the addition of cement, you get a reliable and moisture-resistant coating. One of the options for use is the finishing of basements with high humidity and lack of sunlight. Please note that lime-based cement plaster is not used for wall decoration in new buildings. Given the cost of materials, it turns out too expensive. But for repair and restoration work, such a mixture will be indispensable.
- Gypsum. The best option for finishing wooden surfaces, however, requires certain skills in work. The fact is that gypsum has a fast setting, so the solution is made in small portions and immediately applied to the surface.
- Sand. This is the most common version of lime plaster. Prepare the mixture and perform finishing work even for a beginner. In addition, the cost of lime-based sand plaster is surprisingly low, which may explain its popularity. Please note that before starting work, the sand must be sifted and washed, otherwise it will not work to get an even layer of plaster.
- Clay. The use of this material as a plasticizer is extremely rare. This is due to the specifics of the application: leveling and fixing clay surfaces.
Proportions
Ready-made lime mortar can be purchased ready-made, however, real masters prefer to mix the composition on their own. For this, there are special recipes for each of the above fillers. We’ll clarify right away that average proportions will be given here, which can be changed to obtain the optimal consistency.
- Sand plaster on a lime basis. To prepare such a solution, mix lime with sand in a ratio of 1: 4, respectively. The amount of water depends on the desired consistency of the solution. To ensure better adhesion, some masters include PVA glue in the composition.
- Gypsum mixture. In the manufacture of such a composition, a ratio of 1: 3 for lime and gypsum, respectively, should be followed. Please note that the prepared mixture begins to harden literally 5 minutes after kneading. Therefore, the recommended volume of finished plaster should not exceed 4-5 liters, otherwise you simply will not have time to use it.
- Lime-clay. The proportions of clay and lime in the composition are 1:1. In addition, it is recommended to add 1/6 of the sifted sand.Please note that pure clay is not used for the preparation of plaster. Therefore, you will need to pre-prepare the clay dough. This material is obtained as follows: quarry or powder clay is diluted with warm water and settled for 2-3 days. The resulting mixture is then filtered through a fine sieve. Such a solution does not have high strength indicators, so sawdust or shavings can be added to strengthen it.
- Lime-cement. This is a complex mortar, which is ideal for finishing damp rooms. Recommended ratio: 1:5:1 for cement, sand and lime respectively.
Subtleties of cooking
Please note that only slaked lime is used to make any solution. Given that lime slaking is a rather long process, finishing work must be prepared in advance. To prepare lime for further use, it is necessary to mix quicklime with water in a ratio of 1:2. For these purposes, it is necessary to select a large volume container: in the process of slaking, lime increases at least two. In addition, the process is accompanied by high temperature and the release of lime fumes, so take care of a respirator and rubber gloves.
After slaking, the lime must stand for 24 hours, and only after that you can start making the solution. To shorten such a long preparatory process, you can use quick-extinguishing lime: it will take 30-40 minutes to prepare it.
Application process
Work with lime mortar consists of several stages. Let's consider each item in detail.
First, knead the solution to the optimum consistency. You can check the readiness of the plaster for use as follows: we pick up the finished composition with a shovel. If the mixture flows freely, then there is an excess of water in the solution - we add material. When the shovel hardly comes off the mixture, it means that the solution turned out to be too viscous - add water. The best option: the solution lies evenly on the surface of the shovel.
Having prepared the plaster, you can start leveling the walls. To do this, the surface is cleaned as much as possible from the remnants of the old coating and dust. Then they install special beacons made of a metal profile. This nuance will greatly simplify the process of applying plaster to the wall surface. The distance between the beacons should not exceed the width of the rule with which the mortar will be leveled.
After that we carry out surface spatter. To do this, you will need to prepare a mobile solution using two parts of sand, one cement and 1/5 lime. The composition is sprayed on the surface of the wall with a spatula or trowel. It is not necessary to equalize the mixture.
Next, we apply the main layer of plaster, prepared according to one of the above recipes. The solution is applied from the bottom up, the recommended layer thickness is no more than 5 centimeters. When the plaster sets, beacons are removed, the surface is leveled and a finishing layer is applied.
The drying time of the plaster directly depends on the materials used. For example, the applied gypsum mortar will be ready for further finishing in an hour, and the lime-cement mixture will dry for 2-3 days.
