Natural stone is a valuable material for interior design. However, its price is high. Qualitatively simulated artificial stone for a simple man in the street in most cases is indistinguishable from natural products. At the same time, it costs less, weighs less and can have a variety of textures. Modern polyurethane molds and innovative painting technologies are able to transform ordinary concrete or gypsum into an exclusive material that is almost as good as a natural product in appearance and quality.
Form material
For the manufacture of high-quality forms that can accurately convey the texture of natural material, polyurethane rubber has recently been used. This unique material is wear-resistant, elastic, corrosion-resistant, and can withstand significant mechanical stress.
Polyurethane molds are made by cold polymerization. The raw materials for the molds are two-component polyurethane compounds. Despite the apparent simplicity of the technological process, considerable experience is required for the manufacture of matrices, because the quality of the finished product depends on the shape.
The cost of the finished form is several times higher than the cost of raw materials for the manufacture of the matrix. A well-made mold is able to copy even the imprint of a human hair on the casting with incredible accuracy.
Polyurethane manufacturers
Today, more than two hundred different polyurethane compounds are produced in the world. For the production of artificial stone, molds are needed that combine optimal density, strength, elasticity and casting consistency.
Ecomould's two-component compounds are of medium fluidity (liquid honey consistency), suitable for the production of artificial stone with small negative angles. Compounds are relatively inexpensive and are suitable for small runs of concrete products with a simple relief.
VytaFlex Series polyurethanes are characterized by greater elasticity, good wear resistance, and a wide choice of strength characteristics. The use of matrices from such compounds makes the process of stripping products easy and fast even without the use of release agents.
Duramuld's polyurethane molds and LEPTA-108 CX compounds are suitable for gypsum castings, they also withstand the alkaline environment of concrete, and are adapted for hand-made molds without the use of vacuum degassing.
Advantages of polyurethane molds
Polyurethane molds for artificial stone have a number of advantages. Due to their elasticity, they make it possible to easily remove finished castings with minimal product waste. Compared to plastic molds, concrete products in flexible molds can be cured in half the time.
Due to the precise detailing of the front surface of the copied sample, it is possible to achieve the similarity of the finished product with the texture of tree bark, petrified bone, antique fresco and other materials. The molds are durable, even with an intensive production mode, their margin of safety is enough for 2-3 years of operation.
It is possible to expand the range of products using concrete and modified gypsum as raw materials. The ability of polyurethane to hold dye particles on the surface of the molds combines the painting process with the molding material pouring the matrix.
Shape selection
Polyurethane is a capricious material. To guarantee the quality of a mold made from such a material, you need considerable experience in the manufacture of dies, you also need to know the subtleties of the technological process, follow the polymerization regimes, and use proven compounds from leading manufacturers of cast polyurethane in production.
The choice - to buy a ready-made matrix or to make it yourself - depends on many factors. Making the perfect polyurethane molds for stone at home without experience is quite difficult. Since raw materials are not cheap, it is better not to experiment, butpurchase a ready-made matrix. This option is suitable if there is confidence in the professionalism of manufacturers.
On the other hand, by making molds on your own, over time you can gain the necessary experience and not depend on the existing range of finished products, but easily expand it, making new types of finishing materials that competitors will not have.
Making a matrix with your own hands
To make polyurethane molds with your own hands, you need an artificial stone or samples of natural material and two-component molded polyurethane. For the manufacture of the frame, it is necessary to prepare an even piece of MDF or chipboard according to the size of the mold and pieces of boards for the sidewalls.
Copiable samples of stones are attached to the surface of the slab with sanitary silicone. The distance between them and from the samples to the side walls should not be less than one centimeter. Next, the formwork from the boards is mounted. The joints of the frame are sealed with silicone. Samples and formwork are treated with a release agent.
Polyurethane is prepared as follows: the components are measured into separate containers according to the instructions and mixed without foaming until smooth with a low-speed drill with a nozzle. The prepared solution is poured over the samples above the level of stones by 1-3 cm. After settling for 24 hours, the formwork is disassembled, the samples are removed from the mold, it is allowed to settle for the time necessary for the technological process.
Industrial molds
Organizeindustrial production of molds was tried repeatedly, however, the complexity of detailing the surface of the copied material made the attempts ineffective. Nevertheless, mass production of molds for artificial stone on machine tools has been established.
This technological process was mastered by "Zikam Stone" company. Polyurethane molds produced using its technology are almost two times lower in price than similar imported molds. Some characteristics of the molds even surpass samples from leading manufacturers using the cold polymerization method.
Forms made by machine are distinguished by stamping on the reverse (rough) surface of the matrix. Ordinary casting molds can only be marked on the front or side.
Selecting a quality matrix
If you decide to purchase industrial polyurethane molds for the production of artificial stone, you should pay special attention to their back side. In a quality matrix, it should be smooth without the slightest porosity.
The presence of traces of escaping air bubbles will indicate that the entire thickness of the matrix is saturated with air. This form will not last long. To determine the strength, you can try to pinch off a piece of material from the matrix - high-quality polyurethane will actively resist this. A cut thin strip from a matrix sample breaks with force when stretched.
It makes sense when buying a matrix to insist on a test fill in the presence of the sellerfast curing compound. The cast sample should have a clear relief of natural stone without polished smoothness and gloss. Excessively thick bridges and sidewalls (up to 3 - 5 cm) will indicate the replacement of polyurethane with a similar material with similar properties.
Polyurethane molds from "Zikam Stone"
Paving slabs imitating rubble stone, imitation of marble, limestone, sandstone, slate compositions, decorative bricks and stone veneer - all this is possible with Zikam Stone technologies. Polyurethane molds made by the specialists of this company are ideal for the production of cement-based artificial stone. Plaster can be used to make original stucco, mosaics, moldings and bas-reliefs.
For those who want to try their hand at the production of artificial stone, "Zikam Stone" offers materials for home-made polyurethane matrices. Economy class kits are available, containing, in addition to basic polyurethane casting matrices, a detailed process manual, modifying additives and pigments for gypsum. The "Standard" class equipment, in addition to the listed materials, also has a sample for painting and additional technological equipment. The Premium package additionally includes a professional airbrush and matrix trays.
Quality polyurethane forms "Zikam" even in a small private workshop make it possible to establish the production of artificial stone. With duequality products and reasonable prices, such a business can compete even with factory production.
