How to dilute plaster for topiary. Gypsum details

Smooth walls- this is collateral quality repairs. And one of the simple and reliable ways to level and decorate walls is to plaster them. In this article we will examine in detail all the issues related to gypsum plaster: what is it for, what are its features and specifications, pros and cons, and applications. We will also clearly show how to work with this material.

Application of gypsum plaster

Plaster mixtures based on gypsum are used for finishing primarily walls and ceilings living rooms, as well as other rooms with normal humidity.

It can be placed on such bases as:

• brickwork and clay walls;
• on top concrete walls and (requires concrete contact treatment);
• on old gypsum plaster, provided it has good strength;
• for cellular foam concrete, aerated concrete and expanded clay concrete;

Since gypsum is capable of absorbing moisture, it is used only for interior decoration dry rooms when preparing the surface or.
Gypsum plaster can be produced in the form of:

• starting mixtures or ready-made solutions;
• fine-grained finishing;
• decorative compositions.

Current prices:

Gypsum plaster

What's included

The main component of this type of plaster is building gypsum - calcium sulfate hydrate, obtained by firing gypsum stone and ground to a powder. The following may also be added to the composition:

• fillers that reduce weight and increase the thermal insulation properties of light plaster: perlite, vermiculite, foam glass or expanded polystyrene;
• plasticizers and retarders;
• additives that increase surface whiteness - salts various metals(zinc or titanium white) or lime;
• components that increase their strength;
• additives that regulate the setting time of the solution and its hardening time.

Gypsum plaster is environmentally friendly clean materials and is absolutely not hazardous to health. Moreover, due to its hygroscopicity, it is able to “breathe”, that is, absorb excess moisture and, on the contrary, release it, thus regulating the microclimate in the room.

A separate type of gypsum plaster is gypsum polymer. It is used for leveling brick and concrete surfaces. In some cases, gypsum polymer compositions can also be used for exterior finishing work.

Specifications

The quality of mixtures based on gypsum binder is regulated .

• According to this document, the main indicators of dry material include:
• humidity: moisture content is allowed no more than 0.30% of the total mass;
• maximum size of granules (grains);

volumetric weight: 800-1100 kg/m3 (loose) and 1250-1450 kg/m3 (compacted).

• Properties of the prepared solutions:
• water consumption when mixing - 0.6-0.65 l/kg
• mobility: the ability to spread under the influence of its own weight; according to GOST 31376, the diameter of the melted sample of the prepared solution (~600 g) should not exceed 165 mm (±5);
• setting time - at least 90 minutes for machine-applied mixtures and 45 minutes for manual plastering; complete drying time - after 5-7 days; this indicator depends on the additives in the mixture and differs different manufacturers
• ; You can find out exactly how long it takes for the plaster to dry in the instructions on the package;
• ability to retain moisture without allowing it to drain: at least 90%;

consumption for a layer of 10 mm is 8.5-10 kg/m2 (manual application) and 7.5-9 kg/m2 (machine application).

• Properties of gypsum plaster in hardened form:
• compressive strength - 2.5 MPa;
• surface adhesion force - 0.3 MPa;
• density - 950 kg/m3;
• vapor permeability - 0.11-0.14 mg/ppa;
• thermal conductivity - 0.25-0.3 W/m*C;

shrinkage - does not shrink

Although the vapor permeability (the ability to transmit water vapor) of plastered surfaces is not regulated by GOST, it is also an important technical characteristic that determines the scope of application of the plaster.

When purchasing gypsum mixtures, you should pay close attention to their shelf life. Due to their ability to easily absorb moisture, they cannot be stored for longer than 6 months from the date of release. After this period, their properties change, they begin to clump, and high-quality leveling of walls with them becomes problematic. It is also necessary to pay attention to the tightness of the packaging, which protects against excess moisture - you should not purchase plaster in torn bags.

Advantages and disadvantages The main disadvantages of this material include low moisture resistance and strength - a surface plastered with gypsum can be scratched or chipped quite easily. The cost is a little higher than, by about 15-20%, but this is an insignificant minus.

But still, gypsum has many more advantages:

• high plasticity: working with gypsum mortar is easier than with others; the labor intensity of the process is significantly reduced, and this is a significant plus;
• no shrinkage: for cement mixtures it is a couple of millimeters per square meter;
• surfaces plastered with gypsum are smoother, without pores or graininess;
• good adhesion: gypsum mortar adheres to the surface much better than sand-cement mortar; therefore, reinforcing mesh may not be used to strengthen the surface; it is required only in new stands due to possible shrinkage of the building;
• good heat and sound insulation properties: a wall covered with a layer of gypsum retains heat and protects from noise better than concrete surfaces;
• it can be applied in a thicker layer (up to 50 mm) without reinforcing mesh;
• light weight: walls covered with gypsum place less load on the foundation;
• profitability: when comparing costs, many people pay attention only to the weight of the pack; however, it is necessary to take into account specific gravity mixture - after all, the consumption of gypsum per 1 m2 is 9-10 kg, while cement for plastering the same area will require 16-18 kg.

Expert opinion

Alexander Guryanov

Plasterer and decorator

Many people attribute the advantages of gypsum to a higher setting speed than cement-sand mortar. However, it is difficult to call this a significant advantage. Indeed, a surface treated with gypsum plaster hardens 1-1.5 hours faster than one coated with a cement composition.

You should not hesitate when working with it - smoothing out the solution that begins to harden will be problematic. Do not dilute the mixture too much if you are working on your own. It is better if one person does the cooking and the other does the plastering.

How to dilute dry mixture

Let's consider the preparation process and proportions of the gypsum solution. The dry mixture from the bag is poured into a prepared container already filled with water. According to the instructions, 1 kg requires 600-700 ml of liquid, that is, a 30-kg bag of plaster will require about 20 liters of water.

A small amount of solution can simply be mixed with a trowel or trowel. If it is difficult to make large volumes with your own hands, then it is better to use a hammer drill with a mixing attachment or a construction mixer.

The solution should stand for 3-5 minutes (reaction time of the components). Then it is thoroughly mixed again until complete disappearance all the lumps. The solution should be viscous and plastic, but under no circumstances should it flow off the instrument.

Gypsum plasticizers

However, at home it is quite possible to make gypsum-based mixtures with your own hands, for example, quite plastic ones. But the reaction between gypsum and water occurs quite quickly, so gypsum plaster hardens quickly.

To make a solution convenient to work with, one of the plasticizers must be added to it:

• diluted PVA glue, about 1% of the total volume;
• lime, used as a plasticizer and to increase hardening time;
• wine, lemon acid will also slow down setting. WITH special liquids, for example, Plast Retard PE, can extend the setting time to several hours, prevent the appearance of cracks and improve the wear resistance of gypsum.

Use in damp rooms and outdoors

As we have already mentioned, gypsum plaster is capable of absorbing moisture, so its use in wet areas and even more so for facade finishing not advisable.

If it is necessary to make the gypsum surface moisture resistant (for example, when preparing to lay tiles in the bathroom), it is coated with a deep penetration primer. acrylic base. Concrete contact soil is ideal for tiles.

Polymer waterproofing mastic, for example, Plitonit Gidroelast, also has good moisture-protective properties. It is applied on top of a thoroughly dried layer of plaster using a brush or roller in several layers. Each of them must be applied after the previous one has dried. Gluing of tiles is allowed only one day after application. It is recommended to fill the outlets of pipes and corners of various structures with the same mastic.

How to plaster with gypsum mortar (video)

You can work with gypsum plaster using a plastering station or manually. Machine application is a separate topic for discussion, and we will consider it in another article. And here we will analyze the nuances of manual application.

• the thickness of each layer can be 30-50 mm; if necessary, a new layer can be applied only after the previous one has dried;
• dry mixture consumption in the absence of large irregularities with a layer thickness of 1 cm is on average 9-10 kg/m2;
• gypsum mortar can be applied not only to brick, concrete surfaces and aerated concrete, but also to the previous layer of cement or gypsum plaster;
• surface leveling is carried out using beacon profiles or plaster beacons — small amount a mixture that is applied pointwise or along a line to the wall and leveled; after they dry, a solution is poured between them, and then the entire plaster mass is leveled building rule; the thickness of the layer will be equal to the height of the beacons;
• to remove dust, protect against the shedding of small particles and strengthen the surface after plastering, the surface must be primed;
• to obtain a flat surface before painting or gluing thin wallpaper the walls are additionally puttied;

The video below shows all the stages of finishing: how to properly knead, apply and grout.

Grouting and glossing

Grouting is the manual removal of small irregularities, seams, and transitions between layers. Usually they are rubbed down after the plaster has dried. To do this, take a metal or plastic grater. The tool is moistened with water or a primer intended for application after plastering, and the surface is treated with circular or vertical and horizontal movements, periodically clearing the grater of the solution. Special attention given to the corners.

The video above (time 5:35) shows the process of surface glossing - creating an ideal plane without finishing putty. Glossing and rubbing are very similar methods, using the same tools and techniques. But the difference is that this happens on plaster that has just set and is still wet. This saves time and there is no need to apply putty.

Finishing of aligned walls

After applying a layer of plaster, it is necessary to determine how further finishing will take place:

As you can see, gypsum mixtures are extremely in demand in finishing and repair work and are used everywhere.

We hope that this article was useful to you and that you found the information you were interested in. Please leave your questions and comments in the comments below.

The easiest and most inexpensive way to strengthen the trunk of a tree of happiness or other crafts is plaster or alabaster pouring. You can dilute gypsum or alabaster for topiary in a separate container or directly in the pot. The first method involves diluting a liquid solution, the second - a thick one (to hold the trunk). Each option has its advantages and disadvantages, but in practice both methods are applicable.

How to dilute plaster - 2 methods of pouring

Liquid fill

Dilute plaster (alabaster) liquid solution appropriate for small pot, where kneading a thick mixture will be problematic. In addition, liquid gypsum creates a perfectly flat surface, which is convenient for further topiary decoration. However, it will take at least 24 hours to dry (depending on the volume of the pot). It is this method - optimal and most convenient for pouring topiary.

Dry plaster is diluted with warm water in a ratio of 1 to 1, knead until smooth and pour into the pot to the desired level. The trunk is pre-fixed with plasticine to the bottom of the flowerpot. We recommend immediately washing the mixing container and whisk: the gypsum mixture sets quickly, and alabaster hardens in a few seconds.

Thick filling in a pot

Thick gypsum fill Great for large, wide or shallow containers and is appropriate if you need to continue working on the tree of happiness as quickly as possible: the solution hardens in 3-4 hours.

Pour dry gypsum into the pot, a little lower required level. Slowly adding warm water, knead the solution until a thick, creamy mass is obtained. Insert the topiary trunk into the desired position. It is very important not to overdo it with water: in liquid filling the trunk will collapse and the drying time will increase.

in detail,

"Gypsum (from the Greek gypsos - chalk, lime) mineral, aqueous calcium sulfate salt.

It is found mainly in the form of solid granular (alabaster) and fibrous (selenite) masses, as well as various crystalline groups (gypsum flowers, etc.).

Gypsum is widely used to produce binding materials, for the production of gypsum concrete, as an ornamental (selenite) and facing stone; in the production of paints, enamel, glaze; in medicine and optics.

Plaster serves source material in solutions intended for making hollow spheres from a sculptural original..."

Great Soviet Encyclopedia, third edition, volume 6, page 549.

Artists and craftsmen have long appreciated the properties of gypsum, which is simply irreplaceable for making molds for casting sculptures, copies of models, coins, etc. from various casting materials (wax, bronze, plaster itself), plastics ( organic glass), epoxy resin.

Lubrication

When working with plaster molds, an important role is played by the lubricant that separates the mold from the casting.

For example, when casting relatively simple gypsum objects in plaster molds, the most common lubricant is a solution of stearin or paraffin in kerosene, but for a more subtle transfer of the relief of gypsum castings, soap foam is used (for the same purpose, the molds are washed with potash, soda ash or copper sulfate solution).

An emulsion consisting of soap performed well as a lubricant. vegetable oil and water, taken in a ratio of 2:1:7 (parts by weight). When a sphere is coated with this emulsion, insoluble calcium oleate (calcium soap) is formed. For mass castings, a solution of epoxy resin in acetone is applied to plaster molds.

Grasping

Molding gypsum is a quick-setting binder, and according to GOST, the beginning of setting should occur no earlier than 4 minutes from the moment the gypsum dough is mixed, and gypsum hardens no earlier than after 6 minutes, but no later than 30 minutes.

To regulate the setting time of gypsum, special substances are used - inhibitor and catalysts, of which the former slow down the reaction, and the latter accelerate the setting.

For mixing, 5-10% wood glue is used as inhibitor solutions, as well as some solutions: 2-3% - borax; 5-6% - sugar; 5% - ethyl alcohol.

3-4% solutions are used as mixing catalyst solutions table salt, sodium sulfate, potassium sulfate, etc.

Hardness

To increase the hardness of a gypsum product, fluff lime, sifted through a fine sieve, is added to the gypsum product before mixing. After which the gypsum is sealed, the solution is thoroughly mixed and poured into the mold. After the plaster has set, the castings are dried in a warm place.

Impregnation of its products for 24 hours with a solution of 5% ammonium borate, heated to 30 degrees, gives strength to gypsum. Note that ammonium borate must be properly prepared. And they do it like this. First in warm solution boric acid in water add small portions while stirring ammonia until the litmus paper begins to color Blue colour(liquid has pH = 6-7). After which the liquid is allowed to stand.

Glauber's salt increases the strength of the casting, the solution of which is used to treat the finished casting.

The hardness of gypsum will increase significantly if it is mixed with water containing up to 50% silicic acid, and the finished casting is then heated to 60-80 degrees.

Another method of giving gypsum strength is to mix the gypsum in an almost saturated solution of borax. The finished casting is first impregnated with barium chloride and then covered with hot soap solution and washed with water.

One of the best ways To obtain high-hard gypsum, a 2-hour impregnation of a gypsum casting with zinc or iron sulfate is required.

It is permissible to treat gypsum castings with potassium alum, which also increases the hardness of the gypsum. After keeping the product in a saturated alum solution for about a day, it is allowed to dry, after which the casting is heated to a temperature of 550 degrees. Gypsum treated with alum hardens slowly, but once hardened, it resembles ceramics in strength.

Note that with an increase in the amount of water added to mix the gypsum, the strength of the latter decreases, since excess water evaporates, resulting in the formation of pores in the gypsum.

Cleaning contaminated plaster casts

Plaster casts become dirty over time. The reason for this is dust and a rag, which is used to wipe this dust off the castings. Here are some tips on how to properly clean a dirty plaster surface and give it a fresh look.

Tip No. 1. The surface of the plaster sculpture is treated with a vacuum cleaner, then soaked in low-fat milk. The latter is absorbed by the surface of the gypsum, creating a thin film on it, which is casein. Then a layer of mastic is applied, consisting of white wax dissolved in turpentine and a small amount of oil-based zinc white. The mastic is applied with a bristle brush gradually, in a thin layer, as if rubbing the mastic into the surface of the plaster. After the first layer of mastic has dried, a second one is applied after 4-5 days. After this treatment with mastic, a white matte film is formed on the surface of the gypsum.

Subsequently, the plaster sculpture covered with mastic can be washed with water.

Tip No. 2. A simple composition that removes dirt from a plaster sculpture is starch (paste) diluted in water, which is applied to the plaster surface and allowed to dry. The resulting film on the sculpture is scraped off with a wooden scraper, along with any dirt stuck to the starch.

Tip #3: To give a plaster sculpture snow-white appearance it is coated two or three times with zinc white diluted in glue water (a weak solution of wood glue).

Tip No. 4. A very effective way to remove dirt from both plaster and marble sculpture is using synthetic materials based on polyethylene wax.

To prepare a 5-15% paste, polyethylene wax (it turns out there is such a thing!) is dissolved in xylene at a temperature of 40-50 degrees. The prepared paste is applied with a soft, strong brush so that no brush hairs remain on the casting. After formation on the surface polyethylene film the latter, along with the contaminants, is removed

Instructions

Construction gypsum is white with gray tint powder. Grey colour with the addition of water it comes to the fore. Gypsum differs in the degree of grinding: there is gypsum of fine, medium and coarse grinding. The products have high strength with low weight, but there are also disadvantages. Its hardening speed is very high. That is why you need to know exactly how to dilute the plaster, since there will be no time left to dilute and add anything, the raw material will harden. The gypsum should not be mixed too much - this will cause it to harden even faster. The plaster is mixed in small portions, and the master has only a few minutes to mix the composition and apply it in practice.

Any brand used for work requires special dilution, in which water is not added to the powder, but the powder is poured into water. The container for diluting plaster should be such that it can then be successfully scraped off the walls. Plastic and metal containers work well. Dilution proportions are usually one part water to two parts powder. The powder is poured into the water slowly, spreading over the entire area, and slowly stirred until the water completely saturates the powder. Then the solution should sit for 2-3 minutes and thicken without stirring. A sign that gypsum can be used is that the solution has thickened and warmed up slightly. Once the powder has been saturated with water and has begun to thicken, components cannot be added to the solution. Such a solution will be spoiled, since its astringent characteristics will be low.

A high hardening rate is a disadvantage of the gypsum mixture, and several methods have been invented to combat it. First of all, this is the preparation of gypsum adhesive mastic. The proportions are as follows: add 15 g of wood glue to a bucket of water. You can use PVA glue. To prepare, water and glue are thoroughly mixed, and only after that the plaster is added. This mixture begins to fully set approximately 20 minutes after its preparation, which is quite enough for various kinds preparatory activities and bug fixes. In this cooking option, the same rule applies - do not add any components later than others. If the proportions of the solution turn out to be completely inappropriate, it is better to throw it away and start over.

In order to slow down the hardening, add citric or tartaric acid. The proportions for lemon are 0.1-0.2% of the weight of the gypsum. The acid is first thoroughly mixed with water, then gypsum is added. In the same cases, if, on the contrary, it is necessary to reduce the hardening time of the gypsum, salt is added to the water to prepare the solution, mixing thoroughly.

Handicraft is not only a way to spend time interestingly and usefully, but also an opportunity for spiritual relaxation, which is so necessary for people in the modern world.

One of interesting species needlework is the creation of sculptures and crafts, which can be used in the form decorative elements interior, as original gifts and even toys for children. Having decided to take up this type of needlework, you should decide what material to use for the manufacture of this type of product. An excellent solution would be to use gypsum, which is quite easy to work with, and the sculptures and crafts created from it are not only beautiful, but also durable. We will talk further about how to work with plaster.

Crafts made from plaster. How to dilute plaster. Photo

How to dilute plaster for crafts?

Often, those who want to take up such a hobby do not know how to mix plaster for crafts and the proportions that need to be observed. Let's look at some tips on how to make plaster.

How to dilute plaster - proportions

1. The easiest method is to simply dilute gypsum with water in a ratio of 7:10. Such a solution will allow you to create crafts that are easy to process. But such products will not be strong enough and will break easily. Therefore, to ensure greater strength, 2 tablespoons of PVA glue should be added to the resulting solution.

Tip: when preparing the solution, gypsum should be added to water, and not vice versa. This sequence eliminates the appearance, and therefore inhalation, of gypsum dust.

2. The second method of creating a gypsum solution is more complicated, but makes it possible to produce stronger products that will not lose their original appearance over time. When using this method, gypsum is diluted with water and slaked lime in proportions 6: 10: 1 respectively.

How to dilute plaster and then use it beautiful crafts. Photo

How to make a plaster solution for multi-colored crafts?

In order to give liquid plaster color you will need:

• gypsum;
• water;
• gouache;
• jar;
• container for mixing the solution;
• mixing device (spatula, spoon, stick, etc.).

How to dilute multi-colored plaster. Photo

Let's look at the creation of colored gypsum mortar step by step:

1. Gouache is dissolved in a jar with the amount of water necessary to dilute the gypsum.

Tip: to ensure that the gouache completely dissolves, you can close the jar with a lid and shake it.

Tip: gypsum should be poured into the water in a thin stream, stirring continuously, then the consistency of the solution will be as uniform as possible.

3. The solution is stirred until it turns out homogeneous mixture no lumps. The thickness of the gypsum solution should be like that of liquid sour cream.

Tip: you need to mix the solution as thoroughly as possible so that there are no air bubbles left in it, otherwise there will be holes in the product after drying.

How long does it take for plaster to dry?

The setting and hardening of the gypsum occurs within four minutes after making the solution. And complete hardening occurs after half an hour. That's why ready solution gypsum must be used immediately after mixing. To ensure that setting does not occur so quickly, animal water-soluble glue can be added to the gypsum solution.

How long does it take for alabaster to dry?

Alabaster is an analogue of gypsum, which is a grayish powder with a fine structure. It is obtained by heat treatment of gypsum dihydrate. Externally, gypsum and alabaster are practically indistinguishable. But the technical characteristics of these materials have the following differences from each other:

• The setting of the alabaster solution occurs instantly after mixing, so its use is possible only if special additives are added to the solution that delay its drying;
• alabaster is a harder material than gypsum. This can be understood even by touch, by touching products made from these materials;
• using gypsum is safer for health than using alabaster.

How long does it take alabaster to dry? You can answer this question by knowing the technical characteristics of the dry alabaster mixture. The setting of the mixed alabaster solution begins 6 minutes after its preparation. The solution finally sets after half an hour. A couple of hours after dilution, dried alabaster can withstand a load of 5 Megapascals.

Complete drying of alabaster occurs within 1 - 2 days.

So, now you know how to dilute plaster, how to make it colored, how long it will take for it to dry completely and other aspects of working with this material. Next, it's up to you. Show yourself creatively and don’t limit your imagination, then you can create many interesting and exclusive plaster crafts that will perfectly decorate your home or garden!