Until recently, only natural stone was used to clad the internal and external surfaces of buildings. Naturally, not everyone could afford such an ornament due to the high cost of the material. With the advent of artificial stone on the construction market, anyone can decorate their home with it. It is durable, inexpensive, visually no different from natural material, but most importantly, you can make it yourself.
In this article, we will talk about how to make a mold for artificial stone with our own hands. We will also consider what materials can be used in this case and what are their characteristics. But first, let's figure out what an artificial stone is.
Natural building materials have always been expensive. This is primarily due to their production and transportation. Enterprising building materials dealers at one point solved this problem by replacing the stone with samples of similar sizes and textures made from building mixtures.
Artificial stone is obtained by pouring in certain forms solutions based on gypsum or cement. Frozen samples are painted to give them the color of a natural material. In its physical properties, artificial stone is in no way inferior to natural, and in some cases even superior to it. And believe me, visually often even a professional cannot distinguish them.
The manufacture of artificial stone begins with the preparation of special forms (matrices) into which the solution will subsequently be poured on a certain basis. They are needed to give future samples the size and texture of natural material.
The mold for the production of artificial stone should:
- possess high mechanical strength;
- have good abrasion resistance;
- Resist the chemical effects of substances in the solution.
What forms are made of
At home, forms can be made from:
- a tree;
On sale, plastic, rubber and polyurethane matrices are most often found. Consider the advantages and disadvantages of each of the listed materials.
Making a mold for artificial stone with your own hands from wood is not the best option. The frame of the wooden matrix is assembled from boards that knock into a certain shape. The bottom of the matrix is also made of boards or fiberboard. Naturally, there can be no talk of any figured geometry here.
The necessary texture is achieved either by using a special embossed plastic substrate, or by using an old board with many defects as the bottom.
The advantages of wooden forms:
- low cost;
- ease of manufacture.
The disadvantages of wooden forms:
- poor tightness;
- short life;
- the impossibility of manufacturing curly products.
Silicone molds for artificial stone have the greatest elasticity. This allows you to quickly and without unnecessary problems to remove the finished product from the matrix. For the production of molds, the highest viscosity silicone is used.
Advantages of silicone molds:
- high elasticity;
- ideal as a mold for gypsum;
- excellent tensile strength;
- relatively inexpensive to do it yourself.
The disadvantages of silicone molds:
- low chemical resistance;
- the formation of air bubbles during the manufacture of the matrix, as a result of which it may have defects.
Where to get silicone?
Silicone molds for artificial stone are made from silicone, which today can be freely bought in construction stores. It is sold in a kit consisting of the most liquid silicone and hardener, changing the concentration of which you can adjust the density of the material obtained. The cost of silicone in stores starts from a thousand rubles per kilogram, which, you see, is not so cheap, but if the form works out, it will work out three times.
You can save a little if you prepare the silicone yourself from silicon dioxide (water glass) and an acid hardener or ordinary alcohol. Such silicone, of course, will not differ in special quality, however, in extreme cases, it can be used for the manufacture of molds. It should be noted that a solution based on liquid glass thickens very quickly, so all work must be done very quickly.
Making a mold for artificial stone with your own hands from polyurethane is the most common and inexpensive option. Polyurethane has all the necessary properties to create an elastic and durable matrix that will last for more than one year. His best qualities:
- high dimensional stability;
- chemical resistance to oils, solvents, acids;
- low glass transition temperature;
- low inertness;
- high abrasion resistance.
Compared to silicone, liquid polyurethane also benefits from high fluidity. This allows you to accurately reproduce the smallest tiniest texture patterns that are present on the surfaces of natural stone.
What is polyurethane?
Polyurethane - a polymeric material consisting of polyol and isocyanate. Varying the ratio of these components, you can get hard, soft, flexible, or even foamed material. This makes it completely universal for our purposes. Forms for gypsum, for example, are best made from soft polyurethane; for cement, the rigid structure of the material is more suitable. On average, the polyurethane form is able to withstand 1500-2000 castings, and high-quality factory matrices withstand up to 4-5 thousand such procedures.
You can buy polyurethane in hardware stores. It is also sold in a kit consisting of two components: working mass and hardener. The price per kilogram of polyurethane is 700-1000 rubles.
What more is needed?
The next question is how to make the form correctly, and what is needed for this, except for the material? First you need to get a master form, i.e. sample of stone that we would like to produce. And of course, not one. Usually, making a mold for artificial stone with your own hands involves pouring several initial samples. There can be five or ten master forms, depending on their size and the area of the frame.
Samples can be bought at the market or in the same hardware store, and in one matrix it will be possible to place stones of different configurations and textures.
Next, we move on to the formwork, since making a square shape for a stone is possible only with its help. The frame is best made from laminated particleboard or MDF. It consists of four walls, a height exceeding the top point of the largest master form by at least a few centimeters. The bottom of the formwork can be made from a fiberboard or from the same laminated chipboard. The frame structure is assembled on self-tapping screws. If cracks have formed between the walls of the formwork as a result of installation, fill them with acrylic sealant.
When the material for the mold and stone samples are purchased, and the formwork is assembled, you can proceed directly to the manufacture of the matrix.
We fix master forms correctly
Place in the master frame the texture side up so that there is a distance of at least one centimeter between them. Now, using ordinary building silicone, fix each of them by applying a few drops to the bottom of the sample. There should be no gaps between the bottom of the formwork and the master forms. Otherwise, silicone or polyurethane will fill them and samples will not be able to be removed.
DIY mold making for artificial stone
In order for the matrix to have the correct geometry, make sure that before casting the formwork can be installed on a flat horizontal surface. This, for example, can be a table or even a flat floor.
Now we move on to preparing the material for the matrix. The manufacture of a silicone mold for artificial stone (or polyurethane) begins with the mixing of the components. This must be done strictly adhering to the proportions indicated in the manual. Any change will lead to the fact that the form becomes either too rigid, or, conversely, does not freeze at all. The components are mixed using a narrow spatula or a conventional mixer. After stirring the solution, do not rush to fill it into the formwork. Let it stand for a few minutes so that the air bubbles rise to the surface. To make this process faster, the solution container can be heated with a hairdryer.
While air bubbles are coming out, use a stain brush to lubricate the sample stones, as well as the unused bottom surface and side walls with a release agent so that the mold can easily separate from the formwork. As a separator, you can use ordinary engine oil, but in no case do not work out. Lubricating surfaces is recommended in several layers so that the porous surfaces of the stone can be saturated with oil. If this is not done, silicone or polyurethane will penetrate the pores, as a result of which the mold surface will have corresponding flaws.
When this is done, fill the formwork with an even layer of a solution of silicone or polyurethane, until the master molds are covered with a layer no thinner than one centimeter. Leave the future form to solidify for about a day. It is better if the solidification will take place at a temperature of +20 ° C.
We evaluate the result of our work
After a day, the form can be removed from the formwork. Do it better by first disassembling the frame. So it will be easier to separate the matrix from its walls and from stones. If the shape in some places is too tight, pry it with an office knife. Having separated the matrix, turn it upside down and let it dry for several hours. After wipe it with a clean cloth without strong pressure.
The first matrix, of course, can turn out to be imperfect. But do not worry too much, because experience is an acquired business, and in order to produce a sufficient amount of artificial stone, you will need at least five of these forms.