Liquid glass for the furnace: heat-resistant putty with your own hands

The furnace and fireplace operate in a rigid mode: the furnace heats up to hundreds of degrees, the masonry "breathes", expands and contracts, and the usual cement mortar in such conditions quickly cracks and paints. That is why for the repair and coating of furnaces, masters have been used for centuries oven liquid glass — concentrated solution of sodium silicate, which acts as a mineral binder for heat-resistant castings and refractory solutions.

Why sodium silicate is suitable for stoves and fireplaces

Sodium liquid glass is an inorganic material derived from natural raw materials (quartz sand and soda). It has no organic components that can burn or emit smoke, so the frozen silicate film behaves like a mineral: it does not ignite, does not support combustion and retains its strength when heated significantly. This is a key difference from organic adhesives and synthetic resins.

For the furnace, several properties of sodium silicate are important at the same time:

• Non-combustibility and heat resistance — base for refractory castings and furnace coating.
• Binding and adhesive capacity — "glues" filler particles (sand, chamotte, clay) into a monolith.
• Setting acceleration — the solution with the LC additive hardens faster, which is convenient for spot repairs.
• Chemical and water resistance — a frozen seam better resists aggressive environment and moisture.

It is this set that makes liquid sodium glass ETHYZ a convenient binder for furnace work, where heat resistance, strength, and speed are needed.

Where heat-resistant putty on liquid glass is used

Putties and solutions on sodium silicate are used where the seam is heated, but is not in direct prolonged contact with an open flame of the highest temperature:

• sealing cracks and joints of brickwork of the furnace and fireplace;
• coating the furnace and flue ducts with a refractory solution;
• fastening and sealing of furnace doors, grate bars, cast iron elements;
• repair of joints between bricks and metal parts;
• preparation of refractory castings for stoves and fireplaces based on chamotte and clay.

It is important to understand the boundaries: heat-resistant putty on LC tolerates high operating temperatures of the furnace well, but it is not a universal "heat-resistant glue for any degree". For zones of extreme heating and lining of industrial furnaces, specialized refractory mortars and mastics with normalized fire resistance are used.

Approximate compositions of putties

The exact recipes depend on the task, the temperature of the node and the filler, so the proportions given are indicative, specify according to the instructions of ETIZ and for a specific task. Liquid glass here works as a binder and modifying additive, and the "body" of the putty creates a mineral filler.

When adding LC to the cement-sand mortar, it is injected with a small fraction of the cement weight — approximately, specify according to the task. Excessive silicate makes the seam brittle and accelerates setting so much that the mortar becomes unworkable. LC putty with sand/chamotte is usually kneaded to a paste-like consistency and applied to a moistened, dust- and soot-free surface.

How to cook and apply

1. Clean the seam or crack from old mortar, soot and dust, moisten slightly.
2. Mix the filler (sand/chamotte/clay) with the liquid glass in small portions until the desired density.
3. Work quickly and in small areas — the composition sets up quickly.
4. Fill the seam tightly, level, remove excess.
5. Allow to gain strength and dry, the first heating of the furnace should be carried out gradually, without a sharp exit to the maximum.

Characteristics of sodium liquid glass

Sodium liquid glass is standardized by GOST 13078 (without the numerical points invented here — see the documentation for the exact indicators). For the reference point, we give typical values for sodium silicate; exact values — in the ETHYZ passport:

ETIZ produces exactly sodium liquid glass is a universal product for construction, waterproofing and work with concrete. Potassium liquid glass (it is more often used in paints and flame retardants) is another product, and ETIZ does not position it in this line.

Limits and precautions

For a long-lasting result, consider the honest limitations of the material:

• Quick set. Knead in small portions and work quickly, otherwise the composition will "stand" directly in the container.
• Brittleness of the clean film. In its pure form, silicate gives a brittle coating, so it is used for furnaces with filler (sand/chamotte/clay), and not as an independent "heat-resistant varnish".
• Not for areas of extreme heating. For lining and the hottest units, specialized refractories with normalized fire resistance are needed.
• Hand and Eye Protection: Alkaline solution — wear gloves and glasses, avoid contact with skin and mucous membranes.
• Gradual first warm-up. Allow the putty to dry and gain strength, conduct the first kindling smoothly.

By following these rules, you will get a strong, non-combustible and heat-resistant seam. For the choice of a suitable packaging and application issues, focus on eTHYZ liquid glass card and manufacturer's instructions.

Overview of main features.

Liquid glass for the furnace is a mineral binder based on sodium silicate, from which heat-resistant putties and refractory solutions with sand, chamotte or clay are prepared. It is non-combustible, speeds up the set and increases the strength of the joint, but requires quick operation, filler and reasonable temperature restrictions. For furnace repairs, this is a simple and proven material if used as intended.

FAQs

Is it possible to use liquid glass for the oven in its pure form?

In its pure form, sodium silicate gives a brittle film that does not hold well in conditions of heating and movement of the masonry. For furnaces and fireplaces, liquid glass is used as a binder: mixed with sand, chamotte powder or refractory clay. The filler creates a “body” of putty, and the liquid glass binds the particles into a strong non-combustible seam. So the coating is much more durable than a thin silicate film by itself.

In what proportion should liquid glass be mixed with putty sand?

The proportions are approximate and depend on the task, the filler fraction and the desired density, so check them according to the ETIZ instructions. Usually, the filler (sand or chamotte) is introduced into the liquid glass in small portions, bringing the mass to a paste-like consistency convenient for filling the seam. As an additive, a small fraction of the cement weight is introduced into the cement slurry. Excess silicate makes the compound too brittle and causes it to set too quickly.

Does the putty on the liquid glass withstand the high temperature of the furnace?

Sodium silicate is mineral and non-combustible, so the frozen putty with chamotte or sand tolerates the operating temperatures of furnaces and fireplaces well and does not emit smoke when heated. But this is not a universal refractory for any degree: for lining and zones of extreme heating, specialized refractory mortars and mastics with normalized fire resistance are used. The liquid glass putty is well suited for sealing joints, covering the furnace and repairing the masonry.

What liquid glass ETIZ to take for furnace work — sodium or potassium?

ETIZ produces sodium liquid glass — a universal building silicate, which is used for furnace putties, waterproofing and work with concrete. Potassium liquid glass is a separate product, more often used in paints and some flame retardants, and it is not positioned in the ETIZ line. For the preparation of heat-resistant putty for the oven and fireplace, take exactly sodium liquid glass ETIZ in a convenient packaging — cans of 5 liters (7 kg) or 10 liters (14 kg).

How to properly apply liquid glass putty to the furnace?

Clean the seam of old mortar, soot and dust, slightly moisten the surface. Knead the composition in small portions and work quickly — the liquid glass sets rapidly. Fill the seam or crack tightly, level and remove any excess. Work with gloves and goggles as the solution is alkaline. After application, allow the putty to dry and gain strength, and conduct the first kindling of the furnace gradually, without abruptly reaching the maximum temperature.