Use and properties of electrical insulating varnishes KO-921, KO-916 and their varieties

Electrical insulating varnishes are critical to the longevity and dependability of electrical components in a variety of industries. KO-921 and KO-916 varnishes stand out among the many varieties available because of their special qualities and range of uses. These varnishes are made expressly to offer superior insulation, shielding electrical components from the elements and wear and tear.

The exceptional thermal stability and resistance to high temperatures of KO-921 varnish are well known. Because of this, it is the perfect material to use in electrical equipment such as transformers, motors, and other devices that run hot. Its strong insulating qualities also contribute to the longevity of the components it coats and help avert electrical failures.

Conversely, KO-916 varnish is prized for its remarkable flexibility and adherence. When components are subjected to movement and vibration, it works especially well. This varnish creates a strong, resilient layer that sticks well to a variety of surfaces and guarantees reliable performance even in trying circumstances.

Both KO-921 and KO-916 are available in different formulations designed to meet different needs. These variants may have changes for better dielectric strength, accelerated curing times, or increased chemical resistance. In order to provide the best possible protection and functionality for the electrical components, the type of varnish to use will depend on the particular needs of the application.

Electrical Insulating Varnish Use and Properties
KO-921 KO-921 is used to insulate electrical components, offering excellent heat resistance and strong protective qualities against moisture and chemicals.
KO-916 KO-916 is applied for insulation in high-temperature environments, known for its superior adhesion and durability, making it ideal for motors and transformers.
KO-921 Varieties Different varieties of KO-921 provide enhanced flexibility and higher thermal endurance, catering to specific industrial needs.
KO-916 Varieties KO-916 variants are tailored for better mechanical strength and improved resistance to thermal aging, suitable for diverse electrical applications.

Electrical insulating varnishes, such as KO-921 and KO-916, are indispensable for improving insulation qualities and protecting electrical components from moisture, dust, and chemical exposure. These varnishes are perfect for use in transformers, motors, and other electrical equipment because they have high thermal stability, excellent adhesion, and resistance to environmental factors. Different types of these varnishes meet particular requirements, offering solutions for various industrial uses and guaranteeing the dependability and longevity of electrical systems.

Description of the siliconic means for electrical isolation

Glacks under the KO (silicon) brand are made in accordance with GOST 16508-70 and consist of solvent-dissolved solutions of film-forming materials such as resins, cellulose esters, and technical oils. Dielectric materials, which are incapable of conducting an electric current and isolating it, must be included.

Varnishes come in various varieties.

  • Premissive – it is needed to impregnate the winding of the devices, to increase water resistance, increase thermal conductivity;
  • integumentary – used to create a protective coating in areas of insulating parts;
  • adhesive – micro with other materials for gluing leaflets for obtaining a heat -resistant heat -insulating agent (for example, for creating mycalent).

Varnishes can be dried differently. While some of them require drying at temperatures as high as +200 degrees, others produce a solid coating when dried at room temperature.

A few of the most well-known brands are Ko-921, Ko-916 varnish, and its variants. A thorough description of the materials will be provided below.


The instrument is frequently used to soak glass braid cables and wires for equipment and machine electrical insulation. The substance contributes to the formation of an impregnation, a resistant coating that can withstand temperatures as high as +250 degrees with ease. The instrument shields equipment from fungus, liquids, and mold. KO-921 is found in a variety of enamels that resist heat.

  • coating – homogeneous, transparent, without extraneous inclusions, colorless;
  • The proportion of the dry residue is 48 – 52 %;
  • viscosity according to the Viscimim of the BI-4 at +20 degrees-17-27 s;
  • Film drying time to the degree of 3 – 15 minutes;
  • Thermo -elasticity of the coating is 75 hours.

The usage instructions state that the base must be completely dried and that the surface must be free of fat and dirt before applying the varnish. You can use toluol as a solvent as long as you add no more than 20% of it. Application techniques include pouring, dipping, working at temperatures between +5 and +30 degrees, and having less than 80% humidity.


Co-916 material is completed for businesses that fix electrical apparatus. provides electrical insulation as well as moisture and corrosion protection. The substance is used as an insulating impregnation on boards, cables, and wires. Application techniques: dipping and pouring. For fifteen minutes, dry the product at +190… +210 degrees.

  • The film is colorless, homogeneous, transparent;
  • The proportion of the dry residue is 65 – 69 %;
  • viscosity according to the BI-4-45-65 C;
  • Thermo -elasticity at +200 degrees – 50 hours;
  • Coating fortress according to Ma-3-0.5 ec. At +20 degrees.


Although it is a type of earlier fund, KO-916A varnish has unique qualities. This substance is applied to heat-resistant wires and cables to form a winding with fiberglass insulation. High indicators of heat, gas, water, and atmosphere resistance are present in the resultant film.

This tool, in contrast to KO-916, has a smaller viscosity (30–60 s) and a more liquid texture (60 percent of the substances are non-volatile). The remaining indicators fall within the same ranges, and their application techniques are comparable.


For long-term use at +180 degrees or lower, KO-916K varnish is used to impregnate electrical accumulations in machinery, devices, and equipment. The tool’s slight viscosity contributes to its excellent impregnation. Perfectly sticks to metal, dries fast, and cements the winding’s layers and wire curls. The winding is resistant to moisture thanks to KO-916K, which is safe for copper.

  • The proportion of the dry residue is 64 – 68%;
  • viscosity – 45 – 65 C;
  • drying period – 15 minutes at +200 degrees;
  • Thermo -elasticity – 50 hours at +200 degrees;
  • Ma-3 firmness-0.5 ec. at 20 degrees, 0.2. At +180 degrees.

Electrical components must be shielded from moisture, dust, and other impurities by using electrical insulating varnishes like KO-921 and KO-916. These varnishes offer a strong defense against environmental elements, ensuring the durability and dependability of electrical equipment. Their special formulations are intended to improve the insulating qualities, which makes them indispensable in a wide range of industrial applications.

The unique qualities of KO-921 and KO-916 are each designed to satisfy a different purpose. Because of its exceptional thermal stability and resilience to extreme circumstances, KO-921 is a great choice for applications involving high temperatures. Electrical insulation must be maintained even under conditions of extreme stress, and this is made possible by its exceptional dielectric strength. Electrical equipment must operate safely.

Conversely, KO-916 provides outstanding flexibility and adhesion, which makes it appropriate for applications where the varnish must conform to complex surfaces and shapes. Its capacity to create a consistent, long-lasting coating helps shield components from moisture- and contaminant-induced electrical failures, extending component life.

Together with their different formulations, KO-921 and KO-916 offer adaptable solutions for a range of electrical insulation requirements. These varnishes provide dependable protection for specialized equipment, domestic appliances, and industrial machinery. Their use increases overall safety and efficiency by prolonging the life of electrical components and enhancing performance.

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