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The use of gypsum in construction and everyday life has such deep roots that it can easily be attributed to the oldest building materials. But working with him is not easier from this - you need to know not only how to breed gypsum, and what proportions to use, but also many other subtleties associated with this material!
Building plaster - quickly sets, holds for a long time!
In repair work, gypsum is used very widely: both as part of other solutions as an astringent component, and as a "solo". You will find gypsum in stucco mixtures; modern molding and sculptures, as well as gypsum tiles, are made of gypsum. Building gypsum is a white powder with a grayish tint, which intensifies with the addition of water. This material is obtained from gypsum stone, which is burned in furnaces at a temperature of about 150 ° C and ground to a homogeneous powder.
Depending on the grinding, you may find fine gypsum, medium and coarse gypsum - only fine grinding is suitable for construction and repair purposes! The powder used in construction is divided into three temporary groups:
- group "A" indicates the highest setting speed - from 2 to 15 minutes;
- group "B" - these are materials that set no faster than 6 minutes and no later than half an hour;
- group "B" - this group includes gypsum, which solidifies no earlier than 20 minutes.
Gypsum is divided into grades by its degree of compression. For example, material labeled G-6. It is easy to guess what the letter means, but the figure tells us what the ultimate compressive strength of this material is, in this case - 6 MPa. As a reminder of the school curriculum, 1 MPa (megapascal) is the pressure that 10 kg per square centimeter exert.
For construction work, they use material from G-2 to G-7, which belong to group B. By the way, alabaster is a generic name that covers all building brands, and in professional terminology this term has long been abandoned, preferring to specify information using marking. A notable feature of building gypsum is its ability to expand upon hardening, while other materials shrink. The expansion is insignificant - the volume is increasing by 1%, which fits well with the needs of builders and repairmen.
What is still good about gypsum is its high strength and low density of 1200-1500 kg / m 3. Speaking in plain language, this material will be 2 times lighter than the same cement! In addition, it has insignificant heat-conducting characteristics. This all applies to the pros, but there are also disadvantages! The most important thing is the curing speed that is too fast. Therefore, in the work it can not be stored for a long time in this state, or rather, with all the desire you will not succeed, since the gypsum will freeze in the container.
Constant mixing will not save, moreover, this cannot be done, since gypsum will lose its characteristics every minute.
That is why gypsum is kneaded with "zavodki", as the masters call small portions of mixtures. The master only takes a few minutes to use the “factory”, during which he must not only apply it to the surface, but also level it. If this is not done, and the material freezes at least partially, it will no longer be suitable for serious work! This is also called "dead" gypsum, after drying, it will crack and crumble, spoiling you all the work.
Since gypsum powder has low hygroscopicity, its use is rational only in rooms with low humidity. If you are afraid for the condition of the coating, it is better to additionally cover it with a moisture-proof composition after it has completely dried. Since the structure of the material is quite porous, first the surface will need to be prepared - apply the appropriate primer.
Storage conditions - what is gypsum shelf life?
Stocking up with gypsum is an extremely bad idea! Firstly, this material cannot be called scarce, and secondly, no matter how you try to ensure proper storage conditions, 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 a strong union. Even in a perfectly dry room, it will lose its quality over time. The same applies to derivative materials - if you are going to level the walls with drywall, try not to postpone the work after buying materials.
But even if you purchased bags with 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 the ground, for example, on pallets or on bags with other material. If holes formed in the bags during transportation, it is better to close them with pieces of polyethylene.
If you doubt for some reason the quality of the powder, perform simple tests before using it. All you need to do is stir a small amount of material and apply it on a metal surface. Try to pinpoint the time from the moment of stirring to the beginning of hardening - these figures should correspond to the brand declared on the packaging.
How to breed building gypsum - simple calculations
Whatever brand you choose for work, building gypsum needs to be grown 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 a solution, the main thing is that it is then convenient to scrape off the remaining material from its internal walls.
Pour water into the container - one part into two parts of the powder. Then slowly, trying to distribute the powder over the entire water area, stir the mixture until the water is completely absorbed into the powder. At least a little solution should stand - if the material is slightly heated and thickened, it's time to use it! It is very important to remember - in a solution that has already begun to set, you cannot add any of the components separately! By doing this, you spoil the entire mixture, getting a solution with extremely low astringent characteristics.
How to breed gypsum - proportions of different compositions
The disadvantage of a mixture of gypsum powder and water is a very high pour point. It is worth the master to gape, or to make too much a batch, and write is gone! That is why ways were invented to slow down the rate of solidification of this material without losing the rest of its characteristics. The first method is the preparation of plaster glue. 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 glue.
First you will need to prepare a lime-glue mixture. To do this, take 1 kg of glue glue, soak it in five liters of water and leave it for 15 hours - during this time it will get wet properly and get the right consistency. 2 kg of lime dough is added to this mass, it is well mixed and boiled over low heat for 5 hours. As a result, you will get a ready-made concentrate that can be completely or partially diluted in water (for the entire mass - 20 liters of water) and mixed with gypsum.
For one liter of lime-glue solution mixed with water, you need to add 8 kg of gypsum. Calculate also how much water may be needed for this mass - as you already know, it is better to add the powder to the water, and not vice versa, therefore it is recommended to mix the adhesive composition with the liquid immediately, based on gypsum. Such mastic begins to set no earlier than 20 minutes after its preparation, which gives enough time for “maneuvers”. By the way, the addition of ordinary table salt will allow you to get the opposite effect, namely, to accelerate the hardening!
Plaster can rightfully be called the most actively used. decoration material. The likelihood that among the list of goods you buy to carry out repairs there will be several bags with this component is as high as possible. Properly diluted and applied gypsum allows you to achieve exceptionally high-quality results. And how exactly it is necessary to prepare gypsum dough, we will talk in this article.
If we want to obtain a high-strength gypsum mortar, it is best to use the ratio of two parts of powder to one part of water. However, in the vast majority of cases, gypsum dough is required softer. And in order to get an average gypsum solution, one and a half kilograms of powder will require a liter of water. Often, something needs to be done for work, and in this case, a kilogram of gypsum per liter of water will be the best option. By the way, when medical gypsum is prepared, water and powder are taken in approximately equal amounts.
In what proportions to dilute gypsum for pouring molds
Plaster is often used to create various crafts. And in this case, it is usually poured into molds, where the solution solidifies and takes the necessary shape. Speaking about the consistency of the solution for such a fill, we can call the proportions of gypsum and water 7:10. A solution of this consistency is quite liquid and penetrates perfectly into all spaces of the form, which is what we need. But at the same time, the finished product may turn out to be too brittle, so it is best to add a couple of tablespoons of PVA glue to the resulting solution before pouring.
If we are talking about gypsum for topiary, then the consistency of the solution should look like thick sour cream, since the liquid solution will harden longer. By the way, for the preparation of such a solution, it is best to use alabaster, since it hardens especially quickly.
Some rules for diluting gypsum mortar
In the beginning we need a container, and it is best to take a one-time. The reason is simple - in the case of reusable use, washing such a container, we risk clogging the drain pipes. Of course, the packaging should be clean. Gypsum must be poured into the water evenly. At the same time, it is best to interfere with a stainless steel spatula, or with something made of hardwood. As for water, it can also be tap water. Try not to interfere with the solution for too long, as a result of the finished product or a layer of plaster may be weak.
Regarding mixing - it is important to follow a certain technique. The main thing is to prevent the formation of lumps. To do this, you need to evenly distribute the gypsum powder on the surface of the water, and then wait a few minutes until the powder is soaked in liquid. After this, a period of intensive stirring follows for 2-3 minutes. The goal is to make the solution as homogeneous as possible, as well as release most of the air bubbles from it.
Among the numerous materials of a wide range of applications, construction plaster occupies a special niche. It is a mineral of natural origin, which consists of aqueous calcium sulfate, which has a pale gray or white color. Depending on the type, it can have both granular (alabaster) and fibrous (selenite) structure.
Natural gypsum stone is a material with enhanced ductility, which is characterized by ease of application on any type of surface. At the same time, it hardens quite quickly (20-60 minutes) and is easy to process with various tools.
How to knead high strength gypsum
Knead the gypsum yourself
To knead a thicker solution, you need to take gypsum and water in a ratio of 2 to 1 - it is this consistency of the mass that is most often used in finishing work. To obtain a composition of the so-called medium density, it is required to combine in a tank 1 liter of ordinary tap water and 1.5 kg of gypsum powder. But in order to achieve a more fluid construction "test", it will be enough to mix gypsum and water in equal proportions - 1 to 1.
The main rule that is important to observe during the preparation of the gypsum mixture is the gradual introduction of the main powder component into an aqueous solution. Batch addition of gypsum and thorough stirring will make it possible to avoid the formation of lumps, which will favorably affect the quality of your work. It is advisable to work with gypsum by using tools made of hard wood and high alloy steel (stainless steel).
However, in the conditions of work with the specified material, the use of spatulas made of rubber is also allowed. Equally important when working with "liquid" gypsum is gaining time. As already noted at the beginning of the article, the approximate time for gypsum hardening is from 20 minutes to an hour. It is worth giving up the next application of the solution, which has already begun to harden, because otherwise there is a large share of the likelihood of deterioration in the quality of work.
It is recommended to prepare the gypsum mixture to the extent of the required actions that can be performed within the specified time period. At the end of the article, I would like to once again emphasize such an amazing property of gypsum stone as universality. This quality is explained by the fact that it finds application in diverse fields - this is the manufacture of paints and varnishes, and the creation of all kinds of crafts, etc.
This material is very ductile, applied to almost all types of surfaces, hardens quickly and is easy to process. It is used in various sectors of the economy: as fertilizer, components of pulp and paper production, ingredients for the production of paints and enamels. And, of course, burnt powder is used for casting internal elements of building decor, as a cementitious material in construction.
There are special types of building brands. High-strength mixtures and gypsum-cement (pozzolanic) binders are made. Working with gypsum is not very difficult. Hardening, it forms a stone-like mass very convenient for processing. Therefore, it is very widely used for the production of various crafts. Here, its obvious advantage is the high fluidity of the solution, which is very convenient for casting products.
The finely porous 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, so the use of such materials in rooms with high humidity is undesirable. If necessary, apply moisture proof coatings. At the same time, you need to consider how to work with plaster correctly. The porous structure contributes to the absorption of the coating applied directly to the surface. Therefore, a preliminary primer of such a surface should be carried out under the appropriate coating.
How to make gypsum - a few preliminary notes
It should also be noted and the time of work with the solution. Here a lot plays a role in what proportions to breed gypsum. But, in general, the curing time is from 20 minutes to an hour. Reuse of gypsum that has already begun to harden is undesirable, as this affects the quality of work for the worse. This circumstance must be considered before using plaster. It is necessary to prepare a solution with its content only for the amount of work that can be performed over a 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 breed gypsum. It is always useful for minor repairs, puttying, etc. When preparing a gypsum test, you need to take into account the proportions. With 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 and water will be about 2: 1, respectively.
The average density (let's call it normal) will be obtained if you add about one and a half kilograms of the mixture to a liter of water. A very liquid dough, or rather a solution, will turn out in a ratio of water and gypsum one to one.
Knead the gypsum yourself
When preparing a gypsum mortar, you need to know how to knead gypsum correctly. The main thing here is to pour powder into the water in the above proportions with constant stirring. And not vice versa. Moreover, it should be added evenly and gradually, preventing the formation of lumps. You need to know that in this case, a small amount of heat can be released.
In addition, too long stirring is undesirable, because leads to the phenomenon of rejuvenation. To work with gypsum, a tool made of stainless steel or hardwood is recommended, special rubber spatulas, etc. can be used. As already mentioned, the time of work with gypsum mortar is quite limited. Therefore, the technology of working with gypsum, in addition to determining the “portioning” of its preparation, must take into account the associated “layering” of processing.
It is necessary to prepare the already processed part (until completely hardened) with special notches. With a long interruption 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 mezdra or gelatin solution). The opposite effect can be achieved by adding ordinary table salt. In each case, it is worth experimenting with respect to the proportions of the components.
Or for making small sculptures. The technology for preparing the solution is quite simple. The main thing is to know in what ratio the components are mixed. It is worth noting that gypsum is the main material for the manufacture of crafts.
What is gypsum?
Before answering the question of how to properly breed gypsum for crafts, it is worth figuring out what kind of material. First of all, it is very plastic. Gypsum can be applied to almost any type of surface. The material is easy to process and hardens quickly. Gypsum is used in many industries: as a fertilizer, as one of the components of paper and pulp production, as a component of enamels and paints. The material is also used for the manufacture of internal decorative elements. Often, gypsum is used as an astringent component in construction.
Material flaws
Since cultivating gypsum for crafts is a simple process, it is worth considering certain disadvantages of the material. This will greatly facilitate the work with him. First of all, gypsum has low hygroscopicity and strength. Therefore, it is not recommended to use decor elements made of this material in rooms with high humidity. In such situations, additional processing is required. For reliability, finished crafts should be covered with a coating layer that protects from moisture.
Before you start, you should take into account the hygroscopicity of gypsum products. They absorb any coating well. Therefore, it is recommended to apply a primer layer on the surface of the product. Only then can a moisture-proof coating be used. 
How to breed gypsum for crafts: proportions
There are several basic methods for making gypsum mortar for making crafts. The simplest method is to dilute the powder with water. In this case, it is important to observe all proportions. 7 parts of gypsum require at least 10 parts of water. It is worth noting that preparing the solution is with extreme caution so that there are no lumps. It is recommended to add gypsum to the water, and not vice versa. This method also eliminates the formation of dust.
This solution is easy to use. From it you can make products of almost any shape. However, it is worth considering that the crafts are not very strong. They break easily and crumble. So how to breed gypsum for crafts?
Second method
So, how to breed gypsum for crafts. This method of preparing the solution is slightly more complicated than the previous one. However, the mixture allows you to make stronger and more reliable products, which retain their appearance for many years.
To prepare the solution you need: 6 parts of gypsum, 10 parts of water, 1 part. The components are carefully mixed until a homogeneous mass is formed. 
Making gypsum
How to breed gypsum for crafts of different colors? This will require:
- Gypsum.
- Gouache.
- The water is ordinary.
- Jar with a lid.
- Dishes for the preparation of a solution.
- Spoon, spatula or stick.
Kneading process
So, how to breed gypsum for crafts from a multi-colored solution? In fact, the process is quite simple. To begin with, it is worth pouring gouache into the jar and the amount of water needed to prepare the solution. To completely dissolve the paint, it is recommended to close the jar with a lid and shake a little.
Painted water should be poured into the dishes, where the solution will be prepared. Here, observing all proportions, it is necessary to gradually add gypsum. Pour the powder into the liquid with a thin stream, constantly mixing the components. This will achieve a homogeneous consistency of the solution. The mixture should resemble thick sour cream. Mix the solution during the preparation process so that there are no lumps and air bubbles. Otherwise, holes form in the finished product. 
How many crafts do they dry?
Now you know how to breed gypsum for crafts. How much do the products dry? Gypsum solution is seized and gradually solidifies 4 minutes after its manufacture. Therefore, work with the finished material should be quick and accurate. Full hardening of gypsum occurs within half an hour. To set the solution more slowly, it is worth adding a little water-soluble glue on an animal basis to the solution.
What can replace gypsum
At the moment, many sets for creativity are on sale. How to breed plaster for Lori crafts, and the material from other sets for creating figurines, as a rule, is always indicated in the instructions. It should be studied before starting work, as the solution dries quickly. It should be noted that some sets for creativity use analogues of gypsum. The most common of them is alabaster.
This powder has a grayish tint and has a finely divided structure. The material is obtained as a result of heat treatment of two-water gypsum. Thanks to this, the finished solution received completely different characteristics. It is worth noting that outwardly alabaster and gypsum are very similar.
How is alabaster different from gypsum
Among the main differences of these substances, it is worth highlighting:
How much do alabaster crafts
You can determine the curing time of the material by studying specifications mixtures. In general, the setting of the alabaster solution is observed 6 minutes after the dilution of the substance. Partial solidification occurs after 30 minutes. It is worth noting that a stronger and dried solution is able to withstand a load of 5 MPa. The alabaster dries completely within 1-2 days. Despite the fact that products made of this material are stronger, it is not recommended to use the solution for children, since it is not completely safe for health. Gypsum is preferable in this case.
