How to make a mold for artificial stone

Recommendation points

• What are the forms for artificial stone
• Silicone
• Polyurethane
• Plastic
• We make a matrix for a decorative stone with our own hands
• What is a master model and how to make it

From the article you will learn how to save money on “stone” finishing by producing artificial stone at home. A very simple instruction for making molds from polyurethane and silicone is described, advice is given on the choice of material for the molds. You will be able to learn how to produce elite finishing elements at the price of raw materials.

Almost everything is said about artificial finishing stone. Where to buy, how to choose, what is the difference. The only thing left to do is to get the money out of your pocket and buy it. However, in practice, its price turns out to be very tangible for an owner with an average income, who compensates for the lack of funds with his work with love of home..

In the article “Interior made of artificial stone, made by hand”, we talked about how to prepare a mixture for decorative gypsum stone. This article will discuss how to make this finishing material for your own needs as cheaply as possible. The mixture for the production of decorative stone can be purchased ready-made or made on site by mixing the components. But where to get the shape?

The easiest answer is to buy. A variety of offers await you in specialized stores. The cost of one silicone mold with an area of ​​0.24 m² starts from 1200 rubles. a piece. You can make the coveted form yourself and this will give the following advantages:

1. Savings on the purchase of the form. You will pay only for raw materials, and this is several times cheaper.
2. Individual product design. You will be able to choose a stone that suits you perfectly, and not choose from a wide but similar assortment. It is possible to manufacture with any pattern – letters, logos, monograms.
3. A lifelong skill. Once you master the making of simple shapes, you can develop this skill and apply it in other areas (cooking, sculpture).
4. Spin off. The forms, the production of which we describe, are designed for 1000 fillings. Such a product will last a long time and will allow you to produce many times more product than is necessary for your own needs..

What are the forms for artificial stone

The form (matrix) is a plastic flat container with a bottom in the form of the required relief, divided into elements according to the design. The material for their manufacture is used depending on the raw materials with which they are supposed to be filled. Usually three materials are used.

Silicone

Properties:

1. Very soft, elastic and durable.
2. It is prepared by mixing two components – a liquid solution based on silicon dioxide and an acid hardener in a strict proportion.
3. Violation of proportions leads to a change in material properties.
4. The technology involves the removal of air bubbles using a vacuum (vacuum machine).

Application area.There are several varieties of silicone. More liquid grades are used for theatrical makeup, medicine, jewelry and high detail casting. Thicker – for forms for paraffin, concrete, plaster. It is widely used in the food industry as a mold for baking, freezing, etc..

Polyurethane

Properties:

1. Elastic and durable, harder and more durable than silicone.
2. Resistant to chemicals.
3. The quality of transferring the texture to the matrix is ​​not inferior to silicone.
4. It is prepared from two components in simple proportions. The first component is a modified polymer – polyol. It also contains dissolved additives and additives that correct the properties in the solid state. The second (hardener) – MDI (methyldiphenyldiisocyanate).
5. Forming and hardening take place under room conditions, air bubbles are removed by heating (building hair dryer) without vacuum.

Application area.Low rigidity – decorative elements, housings, medical equipment. Medium hardness – molds for plaster, concrete, resins, casings. High rigidity – furniture, car parts, casters, technical gaskets and other industrial products. Wide application in the factory.

Plastic

Rigid shapes with a thin wall, repeating the shape of the product. Insensitive to chemicals. Manufactured from polyurethane at the factory by hot casting and pressing on special equipment. They are mainly used for the production of paving slabs by vibration shrinkage. Out of competition.

So, a superficial overview is enough to determine the material of the future form. Plastic disappears due to lack of factory equipment. We choose polyurethane for several reasons:

1. Universal application. The same polyurethane mold will allow casting from plaster and mortar.
2. Ease of preparation. Proportions of 1: 1, 2: 1 or 1.5: 1 avoid errors, while silicone requires 2% to 6% depending on conditions.
3. No vacuum treatment required.
4. The price is several times lower.

We make a matrix for a decorative stone with our own hands

The whole procedure boils down to keeping the liquid material in the desired shape until it hardens. In other words, we will be creating a shape for the matrix. The principle of operation is the same for PU and silicone.

What you need:

1. Smooth flat table at least 1×1 m in size, standing indoors with room temperature.
2. Smooth varnished (ideally laminated) plywood or chipboard the size of the future shape plus its own thickness (plywood) at each edge. The sides of 50 mm are attached to the bottom and to each other with confirmations. In other words, you need a box for pouring into which the master model will stand..
3. Elements of the master model (stones, even and smooth on one side).
4. Acrylic sealant.
5. All-purpose PVA glue or super glue.
6. Building hair dryer.

What is a master model and how to make it

This is the original of the relief from which the cast will be taken. And there are two options here.

Option one. Large individual elements. They can have a rounded natural or rectangular hewn shape – it doesn’t matter. The range of reasonable thickness for the finished product ranges from 10-50 mm for gypsum and 10-30 mm for concrete and mortar. Do not forget that the finished tiles will have to be glued to the wall. The stone should be flat on one side. Everything is suitable for the form – from marl to granite.

Operating procedure:

1. Trying on the stones on the shape board. We lay them out in such a way that there is at least 15–20 mm between them and between the stone and the wall.
2. We outline the stones with a marker.
3. We install the elements according to the marking, applying universal glue to the flat side.
4. Fill the gaps between the board and uneven edges with acrylic sealant.

Attention! This must be done very carefully and remove the remnants of glue and sealant from the mold..

The master model with large elements is ready.

Option two. Small items, grouped in the form of unsystematic masonry. In terms of terms, this is called a “pile”. To get an impression in such a shape, we first need to create this shape. This is painstaking work. Here you need to make a small box in the size of the model with sides of 20 mm.

Operating procedure:

1. We select the elements of the pile – real strips of sandstone with natural edges.
2. We cut to length on one side so that the width of the strip from the undercut to the natural edge is from 20 to 30 mm.
3. We compose the pile by gluing the strips together. The gaps between them should not exceed 5 mm.
4. When the box is full, we put technical paraffin on the resulting relief and melt it with a construction hairdryer.
5. The heated paraffin wax flows through the cracks and fills the lower part of the master model. This is to prevent liquid polyurethane from filling up the area. Then the model will simply not get out of it..
6. After the paraffin has set, we disassemble the small box.
7. We carefully remove the model, transfer it to a large box (with sides of 50 mm) and place it on glue.
8. Sealing gaps between stones and the plane.

From this point on, the procedure is identical for both options..

1. We install the sides of 50 mm on confirms through a sealant.
2. Key moment. We lubricate the formwork and stone with a separating compound – pure machine oil.

Attention! The release agent is lubricated several times until the pores of the stone are filled. Otherwise, liquid polyurethane will take place in the pores and this can lead to rapid wear of the mold and complications during operation..

3. We set the shape by level in planes.
4. We prepare a polyurethane mixture in strict accordance with the instructions.
5. We fill the formwork with the composition. Alkali-resistant mesh can be laid to strengthen the bottom of the flexible matrix.
6. After the time specified in the instructions, we disassemble the box and carefully separate the frozen silicone from the master model. Removing dissipation.

Despite the apparent simplicity of the technology, skill is also required here. To begin with, we recommend practicing on simple small-sized forms – sawn bricks, tiles, ready-made decorative stone.