Gypsum solution preparation. How to dilute gypsum: all about preparing the perfect solution
This material is very flexible, can be applied to almost all types of surfaces, hardens quickly and is easy to process. It is used in various sectors of the economy: as a fertilizer, components of cellulose and paper production, ingredients for the production of paints and enamels. And, of course, fired powder is used for casting internal elements of building decor, as a binding material in construction.
Exist special types construction brands. High-strength mixtures and gypsum-cement (pozzolanic) binders are produced. Working with plaster is not very difficult. When hardening, it forms a stone-like mass, which is very convenient for processing. Therefore, it is very widely used for the production of all kinds of handicrafts. Here its obvious advantage is the high fluidity of the solution, which is very convenient for casting products.
The fine-pored structure makes gypsum an indispensable material for creating all kinds of injection molds, also with the addition of high-temperature components.
The disadvantages include its low strength and hygroscopicity, therefore it is undesirable to use such materials in rooms with high humidity... If necessary, waterproof coatings should be applied. In this case, it is necessary to take into account how to work correctly with plaster. The porous structure facilitates the absorption of the coating applied directly to the surface. Therefore, you should implement preliminary primer such a surface for a suitable coating.
How to dilute gypsum - a few preliminary notes
The time of working with the solution should also be noted. Here, in many ways, it plays a role in what proportions to breed gypsum. But, in general, its hardening time is from 20 minutes to an hour. Reuse the gypsum that has already begun to harden is undesirable, because this affects the quality of work for the worse. This circumstance must be taken into account before using plaster. It is necessary to prepare a solution with its content only for the amount of work that can be performed during the specified period of time.
As practice shows, he has not yet been able to find a full-fledged replacement, so you need to know how to properly dilute the gypsum. This will always come in handy for minor repairs, putty work, etc. When preparing the gypsum test, the proportions must be taken into account. At more powder, the dough is thicker, the material hardens a little faster. And vice versa. We can say that for a thicker solution, the ratio of gypsum to water will be about 2: 1, respectively.
The average density (let's call it normal) will be obtained if about one and a half kilograms of the mixture are added to a liter of water. A completely liquid dough, or rather a solution, will turn out in a one-to-one ratio of water and gypsum.
We knead the plaster ourselves
When preparing a gypsum solution, you need to know how to knead the gypsum correctly. The main thing here is to pour the powder into the water in the above proportions with constant stirring. And not vice versa. Moreover, it should be added evenly and gradually, avoiding the formation of lumps. You need to know that this may generate a small amount of heat.
In addition, too long stirring is undesirable, because leads to the phenomenon of rejuvenation. For working with plaster, a stainless steel or hardwood tool is recommended, it is possible to use special rubber spatulas etc. As already mentioned, the working time with gypsum solution is quite limited. Therefore, the technology of working with gypsum, in addition to determining the "portions" of its preparation, should also take into account the associated "layering" of processing.
It is necessary to prepare the already processed part (until complete hardening) with special notches. In the event of a long break in work, the already applied and hardened layer should be slightly moistened before starting the application of the next layer of material. If it is necessary to slow down the setting reaction of gypsum, you can use the so-called glue water (glue from the flesh or gelatinous solution). The opposite effect can be achieved by adding regular table salt. In each case, it is worth experimenting with the proportions of the components.
The use of gypsum in construction and everyday life has such deep roots that it can easily be attributed to the most ancient building materials. But it doesn't make it easier to work with it - you need to know not only how to dilute the gypsum, and what proportions to use, but also many other subtleties associated with this material!
Plaster of paris - sets quickly, lasts a long time!
IN repair work gypsum is used very widely: both in the composition of other solutions as a binder, and "solo". Gypsum you will meet in plaster mixes, modern moldings and sculptures are made of plaster, as well as gypsum tiles... Plaster of paris is a white powder with a grayish tint, which is enhanced by the addition of water. This material is obtained from gypsum stone, which is fired in ovens at a temperature of about 150 ° C and crushed to obtain a homogeneous powder.
Depending on the grind, you can find fine, medium and coarse gypsum - only fine grind is suitable for construction and renovation purposes! The powder used in construction is divided into three temporary groups:
- group "A" denotes the highest setting speed - from 2 to 15 minutes;
- group "B" - these are materials that are seized no faster than 6 minutes and no later than half an hour;
- group "B" - this group includes gypsum, which hardens not earlier than 20 minutes.
Gypsum is divided into grades according to its compression ratio. For example, material marked G-6. It is easy to guess what the letter means, but the number tells us what the compressive strength of this material is, in this case - 6 MPa. As a reminder school curriculum, 1 MPa (megapascal) is the pressure exerted by 10 kg per square centimeter.
For construction work, they use material from G-2 to G-7, which belong to group B. By the way, alabaster is a generalized name that covers all construction brands, and in professional terminology this term has long been abandoned, preferring to concretize information using marking. Notable feature stucco lies in its ability to expand during hardening, while other materials shrink. The expansion is insignificant - the volume increases by 1%, which fits well with the needs of builders and repairmen.
What else gypsum is good for is its rather high strength at a low density of 1200-1500 kg / m 3. In plain language, this material will be 2 times lighter than the same cement! In addition, it has insignificant heat transfer characteristics. This all belongs to the pros, but there are also disadvantages! The most important thing is that the speed of solidification is too fast. Therefore, in work it cannot be stored for a long time in this state, or rather, with all your desire, you will not be able to do this, since the gypsum will freeze in the container.
Constant mixing will not save either, moreover, this cannot be done, since gypsum will lose its characteristics with every minute.
That is why gypsum is kneaded with "rods", as the masters call small portions of mixtures. The master only has a few minutes to use the "zavodka", during which he must not only apply it to the surface, but also level it. If this is not done, and the material hardens at least partially, it is no longer suitable for serious work! This is also called "dead" gypsum, after drying it will crack and crumble, ruining all your work.
Since gypsum powder has low hygroscopicity, its use is rational only in rooms with low humidity. If you are worried about the condition of the coating, it is better to additionally cover it with a moisture-proof compound after it has completely dried. Since the structure of the material is quite porous, the surface will first need to be prepared - apply an appropriate primer.
Storage conditions - what is the shelf life of plaster?
Stocking up with plaster is a very bad idea! Firstly, this material cannot be called scarce, and secondly, no matter how hard you try to provide it with proper storage conditions, the treacherous moisture will still find a crack through which it will penetrate into a bag or other container with gypsum and merge with it into strong union... Even in a perfectly dry room, it will lose its qualities over time. The same applies to derived materials - if you are going to level the walls with plasterboard, try not to postpone the work after purchasing the materials.
But even if you purchased bags of gypsum in order to use it in the coming days, special attention should be paid to the storage conditions of the powder. The most important and obvious condition is dryness! It is best to place bags of material 30-50 cm above ground level, for example, on pallets or bags of other material.... If holes have formed in the bags during transportation, it is better to close them with pieces of polyethylene.
If for some reason you doubt the quality of the powder, carry out simple tests before using it. All you need to do is stir a small amount of material and apply it to metal surface... Try to accurately time the time from the moment of stirring to the beginning of hardening - these indicators should correspond to the brand stated on the package.
How to breed building gypsum - simple calculations
Whichever brand you choose for work, you need to breed gypsum on the contrary - not water is added to the powder, but powder to the water! Before starting work, select a suitable container, plastic or metal, to create the solution, the main thing is that later it would be convenient to scrape off the remnants of the material from its inner walls.
Pour water into a container - one part to two parts of powder. Then slowly, trying to spread the powder over the entire water area, stir the mixture until the water is completely absorbed into the powder. The resulting solution should stand at least a little - if the material is slightly heated and thickened, it's time to use it! It is very important to remember that none of the components can be added to a solution that has already started to set! By doing this, you spoil the entire mixture, resulting in a solution with extremely low astringent characteristics.
How to dilute gypsum - the proportions of different compositions
The disadvantage of a mixture of gypsum powder and water is a very high solidification rate. Should the master gape, or make too large a batch, and write it’s gone! That is why ways have been invented to slow down the solidification rate of this material without losing its other characteristics. The first method is the preparation of gypsum paste. For this composition, 15 g of glue is diluted in a bucket of water. Instead of wood glue, you can use another, more complex solution of lime and skin glue.
First, you will need to prepare a lime-glue mixture. To do this, take 1 kg of skin glue, soak it in five liters of water and leave it for 15 hours - during this time it will get properly wet and acquire the desired consistency. Add 2 kg of lime dough to this mass, stir it well and simmer for 5 hours. As a result, you will receive a ready-made concentrate, which can be completely or in parts diluted in water (for the whole mass - 20 liters of water) and mixed with gypsum.
One liter of lime adhesive solution mixed with water, you need to add 8 kg of gypsum. Also calculate how much approximately water may be needed for this mass - as you already know, it is better to add powder to water, and not vice versa, therefore it is recommended adhesive composition Stir with the liquid immediately on the basis of gypsum. Such mastic begins to set not earlier than 20 minutes after its preparation, which gives enough time for "maneuvers". By the way, adding ordinary table salt will allow you to get the opposite effect, namely, to speed up the hardening!
Instructions for the preparation of casting solutions decorative stone
Gypsum is the only construction works a binder that expands and heats up during hardening, while at the same time warping, particularly in thick and long products. In the manufacture of stucco molding, the expansion of gypsum is a positive property, because at the same time, it penetrates into the smallest reliefs of the form (when casting parts). To reduce warpage, gypsum is prepared in lime water (Lime water is obtained by mixing 1 kg of lime dough with 6 - 8 kg of water).
Gypsum mortar
Prepare the solution like this: first, pour into the container required amount water, and then pour gypsum and mix quickly. For filling the molds, a liquid solution is used (1.5 kg of gypsum is taken for 1 liter of water), for drawing out, a medium or thick solution is used (1.5-2 kg of gypsum is taken for 1 liter of water). Large volume it is better to mix with an electric mixer. It is better to mix a small amount with a spatula or an ordinary tablespoon, if the solution is liquid - with a paint brush. Then the solution will quickly turn out to be homogeneous without lumps. The brush should be rinsed immediately in water. It is better to use a container made of polyethylene or plastic. After the plaster has set, they are easy to clean, slightly deforming the container. In this case, the remains of the set gypsum crumble and move away on their own.
Plaster should be prepared very quickly and used immediately. If the gypsum dough (gypsum solution), which begins to harden, is again mixed with water or simply stirred for a long time, the gypsum rejuvenates and stops hardening or setting. It is no longer possible to use such a solution.
Retarders are used to slow down the setting of gypsum. A good retarder is a weak adhesive solution, which, moreover, gives increased strength to gypsum products. For the preparation of glue water, you can use wallpaper glue CMC (it is still found in stores, not to be confused with the usual wallpaper glue) or wood glue. To prepare the glue solution, the following must be done: 1 part by weight of dry animal glue is soaked in 5 parts by weight of water for 15-16 hours or more. After the glue has completely dissolved, add 1 weight part of the lime dough to it and boil the mixture in a water bath for 5-6 hours, stirring it occasionally. The resulting concentrate is diluted with water before use, and gypsum is diluted with the resulting glue water. In terms of its effectiveness, such water is 2-3 times higher than water prepared with ordinary glue solution.
To reduce the warpage of gypsum and slow down its setting, borax is also used, which is taken 0.5% by weight of the total amount of water on which the gypsum is mixed. After drying, immerse the plaster product in the solution copper sulfate(dense blue color), after repeated drying (it will take a long time!), the strength will increase significantly.
To lighten the mass of gypsum products, they are prepared from gypsum mixed with sawdust, which slows down the setting of gypsum. Products can be made with the addition of coarse sand to gypsum or crushed stone screening (fraction 3-5 mm).
It is necessary to dry gypsum products in a warm room with a temperature of at least 16 ° C, but in no case in a draft, which contributes to warping of the cast products.
Lime water also slows down the setting of gypsum, in addition, increases its strength and prevents warping of products. In the production of gypsum products, high-quality slaked lime is necessarily used.
Lime in the production of gypsum artificial decorative stone, and other all kinds of gypsum products is always used and is one of the most important components in the production of gypsum products.
In the production of gypsum solutions for the manufacture of gypsum products, you can use lime dough, as well as slaked lime fluff, but the best effect gives quality gypsum solution lime dough. The quality of products, strength, drying time and many other quality indicators very strongly depend on the quality of slaked lime in the composition of gypsum solutions. finished products from plaster. Lime significantly affects the quality of gypsum products, even if the stone gets into a damp or damp room, it does not absorb moisture and has significant strength.
When making artificial stone from gypsum with the use of painting, it must be borne in mind that if there is lime in the composition, then the rate of pigments and dyes should be slightly increased, because the lime that is in the gypsum is able to partially discolor the pigments, dyes and coloring pastes used for coloring gypsum products. The increase is necessary by 15-20%, while discoloration occurs only in the first days after the manufacture of the artificial stone and painting, and later the dried artificial stone no longer loses its color.
There is another simple way how to prepare gypsum so that the mortar does not set quickly, and there is more time to work with it. Pour gypsum into a container with water, but do not stir, but let it soak in water. This solution can be used a little longer. If you want to speed up the setting of gypsum, you can add salt 1-4 g per 1 liter of water to the water, and / or dilute the gypsum in hot water.
The setting of gypsum is significantly accelerated when it is kneaded with a reduced amount of water compared to what is required for a test of normal density, and vice versa. But at the same time, additional vibration of the poured forms is required to distribute the thick solution over the entire form and increase degassing.
An increase in the temperature of the gypsum dough to 40-46 ° C accelerates its setting, and above this limit, on the contrary, slows it down.
To change the properties of the stone (strength, frost resistance, etc.), various additives are used, the most popular of which is a plasticizer. A plasticizer is an additive that allows you to increase the fluidity and plasticity of the mixture while reducing the water-cement ratio. This increases the final strength and density of the hardened mortar. The plasticizer is sold in two forms - liquid and powder. Both must be diluted in water for ease of use.
The weight of the additives used, including dyes and plasticizers, is determined as a percentage of the solution. On average, the weight is 1-2% of the total weight of the solution, unless otherwise indicated in the instructions for the substance.
Cement-lime mortar
It is prepared in the same way as usual, but instead of water, liquid diluted lime is used. Cement-lime mortar is quite strong and plastic. For making durable lime mortars brands of cements M400 - M500 are used the following proportions cement / lime / sand / crushed stone fraction 3-5:
white cement M400 - 1 / 0.1 / 2.5 / 2.5
gray cement M500 - 1 / 0.3 / 2.5 / 2.5
The simplest and inexpensive way to strengthen the trunk of the tree of happiness or other crafts - plaster or alabaster filling. You can dilute gypsum or alabaster for topiary in a separate container or directly in a pot. The first method involves diluting a liquid solution, the second - thick (to hold the trunk). Each option has its own advantages and disadvantages, but in practice, both methods are applicable.
How to dilute gypsum - 2 ways of pouring
Liquid fill
Dilute gypsum (alabaster) liquid solution appropriate for a small pot, where kneading a thick mixture will be problematic. In addition, liquid gypsum creates a perfectly flat surface, which is convenient for further decoration of the topiary. However, it will take at least 24 hours to dry (depending on the size of the pot). It is this way - optimal and most convenient for filling topiary.
Dry gypsum is diluted with warm water in a ratio of 1 to 1, mixed until smooth and poured into the pot to the desired level. The trunk is preliminarily fixed with plasticine to the bottom of the planter. We recommend that you immediately wash the container and the whisk for kneading: the gypsum mixture sets quickly, and the alabaster hardens in a few seconds.
Dense potting
Dense plaster cast 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, slightly below the required level. Slowly adding warm water, knead the solution until a thick, creamy mass is obtained. We insert the trunk of the topiary in the desired position. It is very important not to overdo it with water: in a liquid fill, the barrel will collapse, and the drying time will increase.
Detail,
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practicality
appearance
ease of manufacture
labor intensity when using
environmental friendliness
final grade
In many areas modern life... It is especially popular in construction, architecture, architecture, medicine. The ability to create a wide variety of crafts from gypsum dough, as well as the ease of processing already solidified material further increase its attractiveness.
Given the environmental friendliness of gypsum and the speed of its setting when diluted with water, we can conclude that unique properties of this natural material. However, working with plaster requires certain knowledge, so first you should carefully study the features of such work, and only then proceed to practice.
When combined with water, the material quickly hardens and retains its shape. In the process of hardening, the solution increases slightly in size with the release of a certain amount of heat. The masters use this property to their advantage: the expanding gypsum tightly fills all the smallest recesses, accurately repeating the internal volume of the form. In this way, many types of plaster decorations are made, as well as various figurines.
It looks like a plaster solution ready for work.
How to breed correctly
The basic rule when diluting stucco is that gypsum powder is slowly and gradually poured into the prepared container with water. During the preparation process, the solution is constantly stirred to prevent the formation of lumps.
For mixing small volumes, use wood, stainless steel, plastic, or rubber products. If the volume of the solution is solid, then it is better to use an electric drill with a special nozzle.
It is unacceptable to stir the solution for more than 1 minute in order to avoid the loss of its properties by the gypsum. Stirring stops when the lumps disappear. If you want to slow down the solidification of the solution, then you should use special additives.
If they are absent, just mix with cold water... This will almost double the time before setting. If you need the solution to freeze as early as possible, add a little salt to it.
How to knead gypsum is shown in the video:
Proportions of gypsum mortar
The rate of its solidification depends on the proportions in which the gypsum solution will be diluted. This time in most cases ranges from 5 minutes to 1 hour. Practice shows that to obtain a solution of medium density, approximately 1.5 kg of dry gypsum powder should be added to 1 liter of water.
If it is necessary to obtain a liquid solution that is used for plastering works, then the ratio of the components is allowed one to one. Liquid solution and will harden longer.
But for the manufacture of sculptural crafts or stucco molding, it is recommended to make the solution thicker. One part of water accounts for 2 parts of powder. This ratio reduces the setting time of the solution.
Silicone forms
Forms for gypsum mortar can be made from the most various materials... This is silicone, wood, metal, epoxy resin, gypsum, extruded polystyrene foam, cement. The main condition for their use is the protection of the inner surfaces of such forms from adhesion of gypsum solution to them.
For dilution, it is better to use elastic forms, for example, silicone ones. They can be used many times without any violation of their integrity. The main advantage of silicone molds is the ease of separating the hardened gypsum mass from them. At the same time, the safety of the hardened models is guaranteed. In addition, these forms do not need to be lubricated.
You can make your own silicone mold. For this, the existing model is fixed motionless in a specially made container. The model is filled with liquid silicone up to its half. After the silicone has hardened, the model is removed. A mold is being made for the upper part of the model.
Some examples of silicone molds for plaster
Form for plaster No. 1 Form for plaster No. 2 Form for plaster No. 3 Form for plaster No. 4 Form for plaster No. 5
How to mold a plaster of paris
Thanks to it, gypsum has a unique fine-pored structure, which makes it possible to make all kinds of injection molds from it. In some cases, plaster molds are simply indispensable in foundry. With their help, copies are cast old coins, figurines, bas-reliefs, models.
Gypsum molds make it possible to use materials such as epoxy resin, plexiglass, plastic, bronze, wax. It is also allowed to make crafts from the same plaster of which the form itself consists. However, in this case, it is necessary to adhere to certain recommendations for pouring.
The plaster mold is cast quite simply and quickly. A thin layer of liquid gypsum solution is poured into a prepared box or other container. When the solution hardens, the lubricated model is laid on it, from which the impression is supposed to be made.
Next, the container is filled with a solution to the middle of the model. After hardening, a plaster form of the lower part of the model is formed. The smeared model is removed from the mold. The mold for its upper part is made in the same way.
For the subsequent pouring of the gypsum solution into such gypsum molds, it is recommended to varnish the molds from the inside in several layers. This will prevent the gypsum mortar from sticking to it. You should also treat the form with some kind of lubricant, for example, spindle oil or a solution of paraffin or stearin in kerosene.
Making an injection mold from plaster:
Plastering with gypsum, process description
The good thing about gypsum plaster is that it can be applied in a thick layer. This allows you to eliminate even significant irregularities in the walls and ceiling. To apply a thick layer (more than 2 cm), the solution must be thicker.
Before starting work, you should prepare the walls. For plaster, it is important that there is no greasy stains, traces of grease or dirt. If metal or reinforced concrete surfaces are plastered, then it is necessary to carry out their anti-corrosion treatment, since gypsum mortar causes corrosion metal products... Further, all surfaces are primed.
The solution is prepared in small portions, since the time of its use is limited. Work is carried out only at a positive temperature inside the room. How to plaster with plaster?
Plastering starts from the ceiling. It is advisable to apply gypsum with a layer of no more than 15 mm. It is better to work with two spatulas. With a short spatula, the mortar is applied to a long spatula, and with its help the plaster is applied to the surface. The applied solution is leveled with a rule-rail and finally smoothed with a spatula.
The walls are plastered in a similar way, but it is permissible for them to use a thicker layer of mortar. In addition, if the walls are curved, it is recommended to install perforated laths-beacons on them, and already plaster on them.
The slats are installed vertically on the walls with putty. The distance between adjacent slats must not exceed the length of the rule. The solution is thrown between the slats and stretched from the bottom upwards. Irregularities are smoothed out with a spatula.
If a second coat is required gypsum plaster, then it is applied immediately after applying the first layer. If the first layer has already dried, then it is obligatory to be primed before applying the second layer.
Painting and painting of plaster products
Plaster products will look completely different if they are painted or varnished. So you can create an imitation of products from bronze, wood, cast iron, marble, Ivory, ceramics and other expensive materials.
For example, to imitate bronze, it is enough to cover gypsum with ocher three times, and to create gilding, gilding with gold leaf is used. Potal is an analogue of natural gold plating, but it costs less. Also, in practice, silvering and patination of gypsum is used.
Varnishes, toners, paints, primers, various ready-made imitation compositions are used as materials for processing products. Due to the porosity of gypsum, priming is a prerequisite. For this, a deep-penetrating primer, PVA glue, drying oil, wood glue can be used.
Some primers, such as glue, are applied in two coats. Only after the primer has dried is the painting of the gypsum products performed. The same paint that will be used to paint your products is suitable for the primer. But it must be diluted in half with water.
You can paint gypsum with almost any type of paints: acrylic, oil, water-based and even enamel. Any types of varnishes are also used. A soft or semi-soft brush is suitable for work.
About features painting of artificial gypsum stone:
Plaster finishing
Most in a known way plaster finish is the creation of stucco molding. It can be manufactured in the most unexpected shapes and sizes. Stucco molding is used to decorate semi-antique ceilings in the form of decorative cornices. Moldings are made to frame doors, windows and walls.
With their help, on the wall, you can create a kind of panel with a picture. Gypsum columns are supports, as well as interior elements large room... With the help of plaster, an already finished column can be turned into a home decoration.
Stucco friezes located on top of the walls around the perimeter of the room will look great. A plaster ceiling rosette framing the chandelier will emphasize not only the dignity of the chandelier itself, but also decorate the entire ceiling
.Using plaster, you can make a three-dimensional decoration of the walls of the room, depicting natural landscapes on them. The plaster dough will easily take the shape of a tree or a piece of rock. So you can independently create truly unique works of stunning beauty.
