Among all the inorganic binders in the foundry industry the leading role belongs to the soluble glass.

The soluble glass is so often used in foundry because of the possibility of achieving the desired technical properties of molds and cores during its application, as well as the availability of this binder.

The main application of soluble glass in foundry is its use as a binder in molds and cores for leading technological process – casting into the expendable molds. Soluble glass in foundry is also used for parting paint production and investment casting.

Different moldable mixtures in foundry require sodium soluble glass with the following characteristics:

1. High modulus soluble glass with silicate module (3.0+3.5 and over) for ZHSS mixtures, glass density – 1400+1420 kg/m3.

2. Middle modulus soluble glass with silicate module (2.8+2.7), glass density – 1480+1520 kg/m3 for code mixtures for “SOG-process”.

3. Low modulus soluble glass with silicate module (2.3+2.7) glass density – 1480+1520 kg/m3 for molding compounds such as FWB.

The use of soluble glass as a binder for foundry molds and cores is based on soluble glass solidification processes that involve expression of the adhesion properties to the refractory filler (silica sand or other refractory sands).

Such solidification of the soluble glass can be performed through ambient (in air) or artificial (heating, hot air blowing) mixture drying or through addition of specific chemical additives – solidifications of soluble glass.

Manufacture of glues

Silicate glue is used in many industries of the national economy. But one of the simplest and most common areas of use has for a long time been its use as a connector for the paper. Since childhood we are all familiar with the liquid transparent glue in plastic bottles. And it is none other that the office version of silicate glue. The proportionate consistency and accurate application of liquid glue allowed sticking together different types of paper and carton. However, it became obvious that with time the glue line becomes yellow and the connection itself – brittle. Therefore, even though the silica glue is still used in the offices, its use is more limited than before.

Manufacture of detergents and cleaners

Soluble glass is used as a water softener (reduction of water hardness though binding of magnesium and calcium ions), thereby increasing both the cleaning ability of detergent substances and their alkalinity. The most common types are potash and sidic liquid glass, that are used for manufacture of detergents for household.

Silicate paints

Water glass paints is the other name of silicate paints, that are the aqueous solutions of sodium silicate (with sodium or potash silicates) with color pigments. There are two types of such paints:

The silicate coating ones that are called bicomponent; except for the glass solution they contain fillers and pigments. These paint do not have organic compounds.

Dispersing and silicate coatings differ from those of the first group, except that apart from the basic elements they also contain synthetic dispersion, hydrophobisator. The share of organic components is not more that 5 %.

Once the reservation that the glass manufacture more often uses soluble glass with potash silicates as far as it provides a more robust and reliable coating.

We should also point out the fact that the paints of the first group are usually used for mineral bases coating; since they are structured with potash liquid, pigments and fillers that are resistant to alkalis, such coatings have good vapor permeability.

The paints of the second group feature simple application, and are used in various fields. Dispersing and silicate paints consist of special water repellent additives. This feature makes them popular in construction works. Walls coated with this paint have considerably longer life.

Why use paint with soluble glass

The paints made from soluble glass can be used for painting the walls and bricks. They are also used for decorating the premises after plastering. Such paints are especially good to be used on surfaces that were once painted with lime, cement or silicate paint. Reservation, it is not recommended to paint the surfaces that were primarily coated with the acrylic or alkyd paint.

Soluble glass paints will be most suitable for interior and outdoor decoration. Today the market is represented by a separate subspecies – façade silicate paints. These decorative paints are designed for facades of buildings. Due to their characteristics of strength, vapor permeability there colors will help you to preserve and protect the façade from the external influences for many years.

It should also be noted that the soluble glass paints are frequently used in automotive industry. For example, in 2008 the Japanese manufacturers began to produce aerosol paints for cars based on soluble glass.

Advantages and Disadvantages of soluble glass paints

We have already mentioned the properties of such paints. This section will focus primarily on their core strength and weaknesses.

Here are some of the main advantages of such paints:

•          high level of vapor permeability;

•          refractoriness;

•          long life;

•          low level of contamination;

•          water repellency (particularly in dispersing and silicate coatings);

•          complete ecological safety.

Nevertheless, such coatings still have some disadvantages.

•          small range of colors as a result of high alkalinity of the paints;

•          high level of diffusion of carbon dioxide. And that is the reason they are not recommended for concrete surfaces.

Manufacture of flame retardants

Refractoriness of silicate paints

One of the main features of soluble glass paints is the their refractoriness. Such decorative coatings fall to the group of non-flammable paints.

The main feature is that the drying paints turn to a film which has flame retardant functions. The most qualitative and resistant to fire are considered to be the paints made from potash soluble glass.

The typical composition of flame retardant paints apart from glass has special fillers that have high flame retardant features. This can include grounded foamed (or not formed) vermiculite, talc, perlite, kaolin wool fiber and asbestos (flaked).

Such paints are usually supplied in double-tare package: a mixture of fillers, pigments, additives and other fillings in one package, and the other contains the soluble glass. The paint should be mixed before application. The mixed substance can be used only during the first 12 hours.

These distinctive characteristics of strength, fire resistance and vapor permeability of the soluble glass paints made the latter irreplaceable for fire resistant painting of walls of any buildings, for creation of a curtains with flame retardant properties, for cinemas and theatres. These paints will enhance the fire safety of any wooden building. In short, with this paints you will not only have a stylish but also a safe building.

Manufacture of various unique types of cement and concrete

Soluble glass is most commonly used in construction; if added to the concrete or cement, these materials acquire hydro and thermal insulation properties.

Hydro isolation

Silicate glue is used for hydro isolation of walls and floors, wells, foundations and basements, which are often subject to negative impacts of wastewaters, changes in temperature and humidity. The use of soluble glass increases the stability of these structures to weathering in several times.

The solution for hydro isolation of wells is prepared as follows: a cement mortar is added with 5 % of soluble glass and mixed thoroughly. The walls of the well smeared with soluble glass diluted with water; at the next stage the walls are coated with the resulting waterproofing solution.

Manufacture of refractory mortar

A solution of soluble glass can be used for laying of fireplaces and stoves. Firstly, a conventional cement-sand mortar is to be prepared (1 part of cement to 3 parts of sand), where after the mortar is added with silicate glue (in the amount of 1.5-5 % by weight of cement). It is better not to dilute a solution in large quantities as it quickly looses its mobility.

Ground stabilization

The primer surface screed

Soluble glass is an ideal material for protection of the basement flooring and attics against water and fire. The inter-floor coverings can not be primed with pure silicate glue, thus a special primer should be prepared. Apart from silicate glue the solution consists of cement and water. The preparation proportions are as follows: 12 kg of cement should be added with 1-5 % of soluble glass. At first, with the help of a nozzle mixer the cement is mixed with water, that should be no more than 3-5 % of mass fraction of soluble glass. After being mixed the mass should be added soluble glass and, again, thoroughly mixed. If the primer dries too quickly, you can add a little water and stir the solution.