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Varieties of seam sealants and instructions for use

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The use of "liquid" gaskets for car repair has gained wide popularity among vehicle owners. The latest generation of sealants have proven to be practical and effective for sealing fluid leaks, replacing gasket materials and fixing various parts. Seam sealant is suitable for body work, glass bonding and restoration of other machine components.

Auto-sealants are used at service stations and when performing repairs on their own. The product range offers vehicle owners an impressive selection of joint sealants that have important technical characteristics and are suitable for solving specific problems.

The main purpose of the compositions is the sealing of seams, joints, joints of parts. For the automotive industry, they produce sealants for tires, engines, cooling systems, optics, and glasses. To choose the right product, you need to consider which site the joint sealant is suitable for. Most often, such a tool is used when performing body work - gluing parts, protecting against leaks, creating a moisture-proof barrier, sealing joints and seams.

Criterias of choice


Automotive chemistry helps to successfully solve problems with the technical condition of the car. A huge list of products of foreign and domestic manufacturers is used for body work, connecting hatches, pipes, eliminating backlash, sealing seams. All sealants differ in properties, composition, consistency and scope.

What criteria to consider when choosing a sealant for a car body:

  • Resistance to engine oil, fuels and lubricants, coolants and other automotive fluids, chemicals.
  • The operating temperature range is an important indicator, since the components and assemblies of the machine heat up during operation.
  • The elasticity of the composition, which ensures the ability of the seams to withstand mechanical, shock and vibration loads.
  • The degree of runoff from vertical surfaces and shrinkage of the substance after complete curing.
  • Adhesive characteristics and effectiveness of adhesion to different surfaces.

Compositions for the treatment of seams of automobile bodies are produced in tubes, cartridges, cylinders of various sizes. Sometimes it is beneficial to buy a capacious container for large-scale body work. If there is a one-time filling of seams or joints, it is enough to purchase a sealant in a small package, since all products have a short shelf life. To make it convenient to use body sealant, a special dispenser tip is provided on the tube. Some products can only be applied with a gun.

Types by composition

Automotive chemicals are hundreds of substances for hermetic connection of various machine parts. For body work, anaerobic, silicone and synthetic agents are used. Technical characteristics, properties and service life depend on the component composition and the inclusion of various additives to increase frost resistance, heat resistance, and moisture resistance.



Professional repair products include anaerobic sealants, often used in service stations and auto repair shops. The products are based on the formula of dimethacrylate esters. The substance has a characteristic property - the composition retains a liquid consistency when interacting with oxygen. In an airless environment, the mixture quickly hardens.

Advantages and Features of Car Weld Sealant:

  1. High resistance to aggressive media.
  2. Immunity to corrosive processes, vibrations.
  3. Wide operating temperature range – from -60 to +300°C.
  4. The optimum setting time without oxygen is 30 minutes.
  5. Versatility - body work, engine, transmission.

After curing, the anaerobic compounds are converted into solid polymers, but the seams remain elastic. It is important that in case of an error or uneven application, the master can correct the defect while the sealant is in a liquid state. The only drawback is the processing of narrow seams and gaps (0.05-0.5 mm).

Note: To obtain high-quality and durable seams, metal parts treated with an anaerobic agent must be pressed very tightly against each other. This helps to displace oxygen at the junction of the surfaces and "starts" the polymerization process.



Silicone-based car body sealant is also a professional product. Strength and elasticity are the main advantages of the composition, the component of which is high-quality rubber. A feature of the silicone substance is hardening upon contact with atmospheric moisture. Polymerization occurs in about 10 minutes - almost instantly.

Advantages of automotive seam silicones:

  • Scope - body repair, glass gluing.
  • Filling gaps and seams of large thickness - up to 6 mm.
  • Good adhesion to metal car surfaces.
  • Ability to maintain its properties at -60 to +300°C.
  • Ease and convenience of application through the dispenser tip.

Silicones are high-temperature sealants, they can be used to restore motors, the compositions are “not afraid” of overloads and high pressure. Durable, elastic, waterproof silicone shows optimal performance. The disadvantages include the need for perfect surface preparation before applying the product.

Synthetic base


Resin is a durable material that can withstand significant loads. Synthetic resins are used to produce sealants for sealing car windows, sunroofs, and headlights. Manufacturers claim that synthetic products are universal, they can be used for a wide range of repairs.

Seam polyurethane sealant for the car has the following properties:

  1. Good viscosity.
  2. Fast curing process.
  3. Resistant to moisture, chemicals.
  4. Long service life.
  5. Universal use.

The tool can be used for car repairs and at home. Synthetic sealants are not as widely used as silicones and anaerobic agents. This is due to some user distrust of the new product. Synthetic-type sealants are classified into heat-resistant for the engine and universal polyurethane for any work - body seams, glass seals.

Variety by purpose

Each sealant is a unique tool with certain properties and characteristics. Joint compounds differ in components, consistency, service life and area of ​​​​use.

In a car, substances are used for various components and parts:

  • Pasting car windows. There are low, medium and high modulus compositions. The glass bonding time is 30 minutes, the strength of the fit in the body is much higher than when using sealing gaskets. The recommended application temperature is +20 degrees.


  • Sticking and restoration of headlights. Cracks in the instruments that provide the driver with visibility reduce the view of the road. Therefore, you can use a silicone adhesive to carefully connect the fragments of the optics. The main advantages are elasticity and strength.


  • Body repair. It is necessary to use seam sealants, with which it is easy to seal seams, joints, gaps on welded elements. This helps to restore the integrity and appearance of the factory structure. For work use tapes, pastes, silicones.


  • Radiators. To eliminate leaks in the cooling system, special polymer-based products are used, which in a few minutes “tighten” the holes formed with a diameter of up to 0.5 mm. The composition must have frost resistance, moisture resistance and permanent tightness.


Separately, it is worth noting products for emergency vulcanization of tires. In the event of a tire puncture, the driver will have time to get to the nearest tire shop to make a full repair. In machine engines (cylinder heads, pumps, crankcases), heat-resistant substances with a wide operating temperature range are used.

Types of body sealants

Means for sealing seams have high adhesive properties. They create a waterproof layer on the treated surface, reliably protect joints from corrosion, and help to firmly connect car parts. There are several types of body sealants. All of them differ in features of use, scope and properties.

Sprayable moisture curing sealant


One-component thixotropic paste contains MS polymers that cure on exposure to moisture. The composition includes a large amount of dry substances. Upon contact with air containing atmospheric moisture, the agent polymerizes. The result is a durable and flexible seam that dries for half an hour.

Advantages of spray formulations:

  • Weld Seam Sealant is suitable for bodywork, underbody gaps, trunk, engine compartment.
  • Effectively works at a temperature of -25 +90 ° C, has waterproof properties and minimal shrinkage.
  • Low fluidity of the substance eliminates the formation of drips on vertical seams.

After drying, the product demonstrates high hardness, withstands strong vibrations, shocks and other mechanical influences well. There are no isocyanates and silicones in the component composition.

Important: You can apply a moisture-curing sealant to the seam with a pneumatic construction gun, paint sprayer. Remove the blocking plate from the cartridge and pierce the tube before using the formulation.

Brush applied sealant


A useful tool for sealing automotive seams is nitrous rubber sealant. Its main advantage lies in the extensive area of ​​​​use - the trunk, pallet, wheel arches, jumpers, bottom, thresholds of the car and other details. The composition is applied with a brush, which simplifies the repair work.

Benefits of the tool:

  1. Thanks to its viscous consistency, it does not leave streaks.
  2. It dries completely in 10 minutes, forming a durable seam.
  3. Reliably protects a surface from water, gasoline, oil.
  4. The composition is ready for subsequent painting after 3 hours.
  5. Joint sealant under the brush is supplied in cans (1 kg).

The tool is suitable for filling gaps, gluing metal parts, processing welds. It can be used to protect bumpers, trunks, engine compartments from corrosion and moisture, and can be used to firmly fix parts. The sealant under the brush comes in different shades, after application it can be painted.



To recreate factory seams on automotive elements, a special tape is used that has the properties of a sealant. The self-adhesive material is comfortable and easy to use. The light green tape is suitable for painting. Before gluing, it is recommended to treat the surface with polyolefin activators of adhesion properties, which dry within a minute. The elastic material fits well with overlapping seams with a small radius. After that, the car part is painted in the desired color.



Extruded sealants are used for interior and exterior body work. They are simply indispensable when it becomes necessary to apply thin sealed seams at the joints of body parts. For uniform distribution of the composition, it is recommended to use a manual or pneumatic gun.

Extruded sealant for the body has the following characteristics:

  • One-component composition.
  • Even distribution.
  • Thick paste consistency.
  • Convenient packaging in tubes of 300 ml.
  • Reproduction of factory seams.

The scope of extruded compositions is extensive - sealing the joints of welds, processing rolled joints, restoring factory seams on hoods, internal surfaces of car doors, trunks, engine compartments. Manufacturers produce products of various shades, which simplifies the further dyeing process (gray, beige, black, white).

How to use correctly


The first rule to follow when applying sealants is thorough surface preparation.

You can choose any composition, but to obtain the desired result, you must follow the following recommendations:

  1. The surface to be treated must be clean, dry and free of grease.
  2. The old gasket is removed, solvents, white spirit are used to effectively remove dirt. about removal of dirt use solvents, white spirit.
  3. Sealing the seams of a car with a seam sealant is carried out by applying the agent to one of the surfaces to be glued.
  4. The thickness of the applied layer must be uniform over the entire length.
  5. When connecting the parts, you need to apply the required force, but do not overtighten the fasteners.

The final curing time of the compositions varies from half an hour to 12 hours. Do not operate the vehicle until the seams sealed with sealant are completely dry. Before processing joints, surfaces can be primed with two-component compounds. Not all sealants can be painted - this information is indicated in the manufacturer's instructions. For the correct choice of sealing agent, it is necessary to take into account the place of application of the composition and its characteristics. The universal repair kit helps motorists solve a variety of car repair problems.