Silicone glue: selection tips, types and properties of silicone compounds

Adhesive materials these are liquid, pasty or solid substances, compositions 1 and compositions 2. When they dry or cure 3, an adhesive layer forms in the gap between the joined surfaces. The strength of the compound is determined by its two main properties:

• adhesion - adhesion of the connecting layer with glued surfaces,
  
• cohesion - adhesion of particles inside the adhesive layer after it has cured.
  

Glues mainly used to connect and fix in a certain position parts and structural elements.

• Adhesive Compounds Designed to fill damaged areas.
  
• Putties have increased strength after curing, so the name came to be - “cold welding” 4.
  
• Sealant adhesives possess the properties of adhesives and sealants.
  

Sealants They are used to ensure impermeability (sealing) of joints of units, assemblies and body parts. The difference between sealants and adhesives is not in their composition and properties, but in the purpose.

• Sealants gaskets Designed to repair "regular" or the formation of new gaskets in their place.
  
• Sealants used to seal threaded joints and to exclude the possibility of self-unscrewing 5.
  

Modern adhesives and sealants, as a rule, consist of a polymer base with various additives:

• hardeners, initiators and catalysts provide fast and complete cure,
  
• fillers (organic and inorganic) improve the properties of the adhesive layer 6, and also reduce the amount of shrinkage during curing.
  

Packing of adhesives and sealants produced depending on their properties and purpose:
- liquid and pasty - in cans, bottles, dispensing syringes (single or double), aerosol cans and plastic or aluminum tubes.

Vials and tubes often have a removable conical dispenser (its tip is cut to the hole of the desired diameter).

For professional use "sausages" and "cartridges" are intended. They require a special extruding manual or pneumatic device, sometimes referred to as a “gun applicator”.

- solid - in the form of briquettes in plastic shells, as well as cords or ribbons rolled up or wound around a reel.

One component 7 materials are placed in a single package and immediately ready for use.
Two-component before use require mixing separately packed parts in a certain proportion.
To prepare the surface before applying glue or sealant, auxiliary materials can be used:

• cleaners - ensuring proper surface cleaning,
  
• "Primers" - accelerating curing, enhancing adhesion and increasing the durability of the connection,
  
• special activators 8 - providing complete curing and increasing the strength of the adhesive layer.
  

When pretreatment with these materials is required, they are applied in a separate package in a set to glue or sealant 9. The application should be indicated in the instructions.

Cyanoacrylate (Cyanoacrylate) Quick Cure Adhesives used for metals, ceramics, leather, rubber and plastics. They do not contain solvents, do not cause corrosion and have a short setting time - from a few seconds to 1-3 minutes. The curing activator is moisture contained in the atmosphere and in microscopic amounts on bonded surfaces.
These adhesives are convenient to use, as they are single-component and well suited for bonding small parts. The best result is achieved by applying glue to one of the surfaces, followed by tight compression. A reliable connection is ensured with a good fit of the parts (the gap is not more than 0.25 mm).
Some cyanoacrylate adhesives can be used instead of soldering. To do this, they add special binders that provide sufficient electrical conductivity of the adhesive layer. Such adhesives are used, for example, to repair damaged threads on the rear window of a car.
For bonding parts under constant exposure to water, cyanoacrylic adhesives are unsuitable. They cannot stick together polyethylene, fluoroplast (Teflon) and polypropylene.
Modified Acrylic Adhesives designed for bonding metals, glass, ceramics, fiberglass, some plastics and various combinations of these materials. They are used, in particular, for gluing rear-view mirrors to the inside of the windshield.
These adhesives are two-component and cure only with the help of special activators. The activator is applied to the surface prior to glue or sometimes it can be pre-mixed with it. In some cases, the components are applied separately in the form of parallel strips.
Acrylic Adhesives UV curing is mainly intended for joining metals with glass and glasses together. In particular, such adhesives are used for fastening the rear-view mirror bracket to the windshield of a car. They are single-component and contain special additives - photoinitiators. Curing of the adhesive occurs only after exposure to ultraviolet light from a source with a specific wavelength. The polymerization occurs within a few seconds, but only in the irradiation zone, which is possible when bonding transparent materials.
For opaque materials, adhesives with auxiliary polymerization methods are used. In this case, only the perimeter of the adhesive joint irradiated with light is grasped - surface polymerization occurs. Further, thanks to special additives, the reaction spreads throughout the glue layer and it completely cures.
Polyurethane Adhesives designed for bonding in any combination of most types of plastics, paper, fabrics, rubber, artificial and genuine leather, fibrous materials, etc. They have very high adhesion, elasticity and water resistance. They are used, for example, in the form of adhesives-sealants for gluing automobile windows.
Issued:

• single component - while in its composition contain initiators of curing 10.
  
• bicomponent - the components are mixed immediately before use, the viability of the 11 resulting formulations in the main from 30 minutes to 3 hours.
  

Duration of curing of the adhesive layer from several hours to two days at room temperature or from 2 to 6 hours at a temperature of from 60 to 120 ° C. To increase the strength of the connection, the bonded surfaces are pre-treated with appropriate cleaners and primers.
Polyurethane adhesives are resistant to the effects of oils, fuels, molds, have good adhesion to most materials used in automobiles. Particularly high mechanical properties are characterized by adhesive compounds of "hot" curing. Epoxy adhesives with and without various fillers are used for gluing metals, plastics, wood, glass, ceramics, as well as metals with plastics and wood. Glues without fillers are used for gluing glass, porcelain, ceramics and gluing them to metals. This is one of the most common groups of adhesives, including various compositions and compositions - from universal EHP glue to special repair epoxy compounds with fillers (the so-called "liquid steel", "liquid aluminum", etc.). Glues of this type have good adhesion and can be used to connect loaded parts, but not exposed to vibrational loads.
Most epoxy materials are two-component, they cure after mixing in a time from several minutes to one hour, depending on their composition, properties of the hardeners used and temperature.
Epoxy compounds can be single-packaged. In this case, curing occurs under the influence of special activators contained in them. In particular, these are solid “cold welds” requiring stirring before use.
Anaerobic Adhesives capable of a long time not to change their properties in the open air, but quickly cure upon contact with an active metal surface in the absence of air access. Both of these conditions are provided in narrow gaps, so anaerobic adhesives are widely used for:

• fixing and sealing threaded connections,
  
• fixing fixed parts,
  
• restoration of bearing seats,
  
• seal cracks in body parts,
  
• filling sinks and other defects in welds, as well as pore casting,
  
• tubeless tire repair.
  

The maximum gap to be filled, depending on the properties of the adhesive, in particular its viscosity, can be from 0.1 to 0.6 mm. Due to its good penetrating ability, the most liquid anaerobic compounds fill well even very narrow cracks (with a width of up to 0.05-0.07 mm).
The curing time depends on the size of the filled gap, the material of the surfaces to be bonded and their condition. It is from 15 to 30 minutes at a temperature of from 15 to 35 ° C. Full cure usually occurs after 24 hours.
There are two groups of the most common materials that affect the cure time upon contact with the adhesive:

• activeaccelerating the process - copper and its alloys, nickel, brass, bronze, low carbon steels,
  
• passiveslowing down the process - high-carbon and stainless steels, aluminum, titanium and its alloys, tin, zinc, metals with anticorrosive and oxide coatings, plastics, glass and ceramics.
  

To accelerate the bonding of "passive" materials, special activators are used. They are applied to one or both surfaces prior to glue. Pre-mix the activator and glue can not.
The strength of the adhesive layer 12 (depending on the purpose) can be high, medium and low. Some manufacturers indicate it with color on the package, for example:

In non-separable compounds, anaerobic adhesives with maximum strength are used, and in often disassembled ones, with minimal. In case of difficulty during disassembly, it is recommended that the connection be preheated to a temperature of 150–300 ° C.
Storage of anaerobic adhesives is possible only in contact with air, therefore, when filling containers, they fill only partially or use air-permeable containers.
Rubber adhesives (elastomers) are used for bonding rubber with metal, glass, leather, wood, fabric, plastic and other materials. They cure due to the evaporation of the solvent, as well as the result of “hot” (at temperatures above 100 ° C) or “cold” (at room temperature) vulcanization 13.
Glues are obtained by dissolving various rubbers, including polyurethane, in organic solvents - gasoline, acetone, ethyl acetate, etc.
Self-vulcanizing adhesives consist of components mixed before use:

The main characteristics of adhesive joints (tear strength, resistance to aggressive media, moisture, heat, cold, etc.) depend mainly on the properties of the rubber used.
Adhesives for Plastics must have a polymer base, similar in chemical nature to the material of the parts to be glued. This allows you to get the most durable compounds.
Universal glues, such as epoxy and polyurethane, are suitable for bonding some plastics, but the strength of the adhesive joint will be lower.
The preparation of joined surfaces when bonding polymer materials is more important than in other cases. Washing, removal of old coatings, ensuring the necessary roughness (the so-called "roughening") and degreasing with organic solvents must be carried out strictly according to the instructions.
Thermoplastic adhesivesmade on the basis of thermoplastics 14 are used mainly for bonding plastics and other non-metallic materials in unloaded compounds. They can be used to connect metals with each other, with plastics, rubber, etc., but are characterized by low heat resistance.
They are produced in the solid state or in the form of solutions of various polymers in organic solvents. Curing occurs as a result of evaporation of solvents or upon cooling after melting.

SEALANTS

Silicone Sealants are used to repair damaged and create (form) gaskets in place of completely failed (cardboard, rubber, cork, paronite, etc.) 15.
In addition, they seal the optical elements (headlights, lights) and fixed joints of windows and hatches of the car.
Silicone sealants are made on the basis of organosilicon (siloxane or fluorosiloxane) rubbers. They are able to cure and gain elasticity under the influence of atmospheric moisture and vulcanizing additives like rubber 16. These sealants can fill gaps up to 6 mm, while the presence of irregularities on the mating surfaces is compensated by the elasticity of the sealing layer. Conventional silicone sealants can be used in compounds having an operating temperature of up to 200–250 ° С, heat-resistant up to 300–350 ° С, and heat-resistant with copper filler up to 375 ° С.
Silicone sealants are not resistant to gasoline - they cannot be used to repair carburetors, gas pipelines, other components and parts of the fuel supply system. Some types of these sealants are destroyed in the environment of ethylene glycol (antifreeze) and motor oils. It is strictly forbidden to use sealants for repairing gaskets of automatic transmissions, since ingress of sealant inside can lead to serious damage.
Polyurethane Sealants They are used as shapers and for sealing joints and joints of car body parts. By properties, such sealants are close to polyurethane adhesives (see above), therefore, they have high adhesion and are unsuitable for dismountable joints.
Anaerobic Sealants (properties: see “anaerobic adhesives”) are used to seal threaded joints, flanges and flat joints with or without conventional gaskets. Unlike silicone sealants, they have sufficient resistance in the environment of motor oil, gasoline, diesel fuel and ethylene glycol. They can be used in compounds whose working temperature does not exceed 80–150 ° С, in rare cases - 175 ° С.
Heat Resistant Sealants Designed to repair exhaust system parts operating under the influence of exhaust gases under vibration and mechanical stress. They can be solid (one of the varieties of "cold welding") or pasty and have a ceramic filler. Apply to oil-free and rust-free and dried surfaces. In some cases, an exposure time of 12 hours is required.

RECOMMENDATIONS

The key to success in car repair using adhesives and sealants is to choose the right one and, more importantly, to apply the necessary composition correctly.
Before work It is desirable to determine:

• the nature of the damage and the need for additional elements (patches, plugs, fasteners, etc.),
  
• what materials are the parts to be glued made of
  
• bonded surface area and required material consumption,
  
• working conditions of the adhesive joint (the force acting on it, temperature, pressure, vibration, etc.),
  
• nature of the environment (the presence of gasoline, motor and other oils, ethylene glycol, water, etc.).
  

When choosing glue or sealant you should carefully study the instructions and determine:

• compliance of the material with the conditions and goals of the repair (are there any contraindications),
  
• the need to use additional materials - a special activator and (or) primer,
  
• the need for auxiliary materials (detergents, solvents, sandpaper, adhesive masking tape, etc.),
  

the need for a tool (brushes, spatulas, applicator gun, etc.),

• the viability of the ready-to-work material (the time of its curing, excluding the possibility of use),
  
• surface preparation requirements,
  
• methods for removing excess glue or sealant,
  
• the amount of materials needed to carry out repairs according to the recommended gluing or sealing technology.
  

1 Composition - a mixture of chemically homogeneous components.
2 Composition - a mixture of chemically dissimilar components, such as epoxy resin and metal filings as a filler.
3 Curing - an irreversible transition of liquid polymeric materials into a solid insoluble state. It occurs in the presence of special substances - activators located on glued surfaces or added to the material before use (in this case they are most often called “hardeners”).
4 Putty adhesives incorporate metal powders consisting of very small surface active particles. They form a strong chemical bond with the polymer molecules of the glue base. In this way, putty adhesives fundamentally differ from ordinary adhesives with a filler, particles of which are only physically interconnected.
5 When using sealant-clamps, moisture penetration into the threaded joint and the formation of corrosion are excluded, which facilitates subsequent disassembly.
6 Resistance to various substances, electrical and thermal conductivity, coefficient of thermal expansion, etc.
7 The terms “one-component” and “two-component” for adhesive materials are conditional in nature, since the number of components in them is much larger. It is more correct to call such materials by the number of packages, for example, single or double packaging.
8 Special activators require artificial application, in contrast to "natural activators", for example atmospheric moisture, always contained on glued surfaces.
9 In this case, the package may include three separate packages, such as glue, hardener and a special activator.
10 In order to better combine components and regulate viscosity, solvents (for example, acetone) are often added to single-component polyurethane adhesives, synthetic resins are used to increase stickiness, and surfactants are used to improve the wetting of the surfaces to be bonded.
11 The viability of the prepared material refers to the possible period of its use from mixing the components to the beginning of curing.
12 For anaerobic adhesives, the bond strength decreases sharply when oiling the glued surfaces, therefore they must be thoroughly cleaned and degreased.
13 Vulcanization is a technological process of the conversion of rubber into rubber, which occurs with the participation of certain substances, most often at elevated temperatures. "Cold" vulcanization is sometimes called "self-vulcanization."
14 Thermoplastics are plastics (plastics) that can soften when heated and harden when cooled.
15 When repairing damaged gaskets of power units of a car, where it is necessary to preserve the specified gap between the connected parts completely, silicone sealants cannot replace the solid gasket, as they are too elastic. They deform when tightened, and it is not possible to maintain the required clearance in the joint.
16 Some silicone formulations, used primarily in industry, freeze when exposed to ultraviolet light.

Introduction to the topic

By nature of origin, silicones are classified as organosilicon compounds. The properties of the adhesive depend on the component composition and structure.

Due to its good adhesion to different surfaces and low cost, silicone glue is very popular in the construction industry.

Its main advantages:

• Resistance to moisture, light and temperature changes.
• Flexible structure under various operating conditions.
• High polymer strength after complete drying.

Silicone-based adhesives are available in a wide range, so it is easy to find a tool for a specific type of work on sale. The compositions are appreciated for their good sealing properties, quick setting and universal use. Thanks to the introduction of modifying additives, adhesives acquire important performance characteristics.

Adhesive Composition

Silicone is a strong polymer compound of organosilicon components with a high molecular weight structure. The chemical has a viscous texture visually similar to resin. The basis of silicone sealant glue is formed by synthetic rubber - an artificial substance that occupies half the composition of the polymer compound.

Some manufacturers separate silicone adhesives and sealants into separate categories.

The fundamental difference between them is that glue is used to firmly fix products, and sealant is used to create a waterproof layer. In composition and properties, the products have similar characteristics.

Silicone glue contains:

• The rubber base of the chemical polymer acts as the basis for the adhesive.
• Strength enhancer affects the viscosity of the substance, gives the required characteristics after drying.
• A plasticizer to improve the ductility of the adhesive mass is made on a silicone basis.
• The primer provides high adhesive properties of the product and adhesion to different materials.
• The vulcanizer is responsible for the drying rate of the glue and its acquisition of a rubbery plastic structure.
• Coloring pigments are not included in all silicone products. Black, white, color dyes mask cracks and seams.
• Fine-grained fillers (sand, glass or silica dust) improve the adhesive properties and strength of silicone.
• Fungicidal additives have antiseptic properties, prevent the formation of mold and fungi.

Some adhesives include curing accelerators, extenders and thixotropic additives. Adhesive sealant is predominantly produced in the form of one-component compositions for domestic use, and in professional work two-component substances are used (base plus hardener).

On a note! Depending on the conditions of application and use, frost-resistant adhesives and high-temperature silicones are distinguished for indoor and outdoor use. All products have excellent water resistance and practically zero electrical conductivity.

The properties

The popularity of silicone adhesives is due to the good performance of the products. In a wide range of manufacturers it is easy to choose a product for gluing specific products and surfaces.

The compositions are convenient to use due to the viscous consistency, which does not drain from vertical planes, forms a uniform layer in thickness.

• High elasticity, remains after drying.
• Resistance to temperature extremes -50 + 200 ° C.
• Inertness to chemical and aggressive substances.
• Intolerance to ultraviolet exposure.
• Adhesion to various types of surfaces.
• Water resistance, frost resistance, durability.

Silicone glue well fills pores and microcracks in materials, reliably fixes fragments of products and structures. The compositions can be used for bonding products that experience mechanical and vibration loads during operation.

The disadvantage of silicone adhesives is incompatibility with polycarbonate, polyethylene and fluoroplastic.

Transparent silicone sealant is not paintable.

Important! Glue can not be applied on wet surfaces - because of the pasty consistency, it will roll. Therefore, before gluing the materials must be cleaned of contaminants and dried, and then apply glue.

Types and Features

The basis for the production of silicone composition is rubber. To give products specific characteristics and properties, plasticizers, fillers, hardeners and other substances are added to the adhesives.

The result is different types of compounds with certain features:

1. Acid-based products. Suitable for gluing all types of materials. But they can not be used for bonding metal surfaces, so as not to cause corrosion, and for delicate products that glue corrodes.
2. Alkaline foods. They include amines and silicon, which have good heat-resistant characteristics. These are special adhesives for outdoor use. Able to withstand high temperatures.
3. Neutral means. Silicone glues any materials. The resulting compound is characterized by high strength and durability. Thanks to deep impregnation, the adhesive adheres securely to the base, acquires hardness, but remains elastic.

The composition of silicone adhesives includes siloxane or fluorosiloxane rubber, which polymerizes upon contact with air. Adhesives vary in form of release, container volume, performance and cost. Silicone product is widely used in everyday life, construction and repair work.

Sealant features include optimum thickness, due to which leveling of uneven surfaces, environmental safety, and rapid curing of the layer within 2-3 hours after application take place.

Attention! The adhesive joint after vulcanization acquires a transparent structure, retains elasticity, has fungicidal and antiseptic properties and high strength.

How to choose glue

The characteristics of silicone substances are not the same, therefore, it is necessary to select a product taking into account operating conditions and the type of materials. To get strong and strong seams, choose quality products.

A waterproof silicone adhesive with a transparent or colored consistency must have elasticity, be protected from external factors, withstand moisture and temperature.

Silicone glue is chosen depending on the scope of operation:

• Compositions of a universal type are used for bonding any materials for all work options - repair, fasteners, sealing. Silicone glue retains its properties when heated and at low temperatures. Suitable for gluing products and structures operating in extreme conditions - heating appliances, heating systems, tile masonry. The composition can be used for gluing glass, ceramics, plastics, apply tight joints to the joints of plumbing, plumbing equipment.

• Means for outdoor use. The scope of their use is gluing and fixing fragments and structures located in the open air. Glue firmly connects wood, ceramics, glass, plastic, suitable for fixing rubber and fabric surfaces. The composition includes an acetic hardener, so you cannot use silicone transparent glue for metals - it causes corrosion. If the label indicates "for outdoor use", the composition is not used indoors due to a characteristic odor.

• Silicone sealants. This is a separate category of adhesives that are used in rooms with high humidity and on surfaces in contact with water. The compositions are suitable for applying sealed seams and forming waterproof joints. Silicone adhesive sealant has good adhesive characteristics, it is used to seal plumbing, water pipes, kitchen sinks.After curing, an elastic layer is formed on the surface that does not allow moisture to pass through.

• Aquarium silicone adhesives. Compositions of natural ingredients, non-toxic, resistant to constant moisture. They can glue the joints of the walls of tanks, containers, aquariums. The presence of markings in the form of a fish on the adhesive label indicates that the product can be used to glue the aquarium without fear of harming its inhabitants. Since the walls of the tank are constantly experiencing water pressure from the inside and air outside, the silicone must have high strength.

• With bactericidal components. Glues are used to connect structures, products, fragments that must meet sanitary requirements. Silicone with special additives has antiseptic properties and prevents the formation of mold. Such a tool is relevant to use in wet rooms (kitchen, bathroom, shower, bath, sauna) and when gluing surfaces in contact with water. The inclusion of fungicidal additives provides an antibacterial effect.

• Car glue is widely used in the repair of vehicles. Viscous consistency, low fluidity, and resistance to temperature extremes allow the use of waterproof silicone glue instead of automotive gaskets, as well as for sealing joints of components and machine parts. Silicones are used for machining engine parts, cylinder blocks, installing glasses, and gluing headlights. The main requirement for the compositions is resistance to dynamic and vibration loads.

• High-temperature silicone glue is applied using a heat gun. Solid transparent rods, which melt when heated, are filled with a viscous-viscous structure. After drying, an elastic seam is obtained. Glue is used in the manufacture of crafts, souvenirs, gluing products from plastic, ceramics, glass. Thanks to the thin opening of the nozzle of the thermal gun, the silicone composition can be applied pointwise.

Before buying glue, you need to make sure that the substance is suitable for a particular material or type of work.

To join metal surfaces, you need to choose neutral adhesives that do not contain aggressive components. And for sealing tile joints acid silicones are suitable, which are easy to remove with special cleaners when dismantling tiles. To fix the plumbing, white compositions are used, and when working with paper, fabric, glass, mirrors, the fragments are glued with transparent silicone glue.

On a note! A feature of silicone-based glue is versatility. With their help, they close the joints of heated surfaces, seal the gaps of window sills, kitchen worktops, tiles made of natural and artificial stone, seal the joints of water and sewer pipes, install mirrors, and paste ceramics. Silicone glue is used in a variety of areas - from the manufacture of crafts to car repairs.

Technology and application rules

To obtain a durable layer of silicone glue, the composition should be applied to well-prepared surfaces.

The products to be bonded must be clean, smooth and dry. If necessary, use degreasing agents.

Silicones are delivered in sealed tubes with an elongated nose - it is convenient to squeeze small portions of glue through such a dispenser.

Technology and rules for applying silicone sealant:

1. Preparation of the parts to be glued - clean from dust and debris, degrease, slightly expand the seams for better filling.
2. You can stick masking tape along the length of the seams so as not to stain adjacent areas with adhesive, for example, tiles.
3. Cut the glue nozzle at an acute angle. To carry out a large amount of work, you need a construction gun.
4. Apply glue to one of the surfaces with a layer of up to 20 mm, press the second part to be glued to it and fix it.
5. Remove silicone adhesive immediately with a rubber spatula or sponge. Complete drying of the mixture occurs during the day.

If you have to work with decorative elements, silicone is selected according to the color of the products.

After the glue has completely dried, masking tape is peeled off. After that, glued elements can be used.

Attention! When the silicone composition dries, mechanical effects, temperature and moisture must not be exposed to the adhesive.

Brands and Costs

Since many domestic and foreign manufacturers are engaged in the manufacture of adhesive products, the price of silicones varies in a wide range. The most popular goods are tubes with a capacity of 330-350 ml, the volume of which is enough for domestic and repair work. The average cost of such adhesives is 200-500 rubles, depending on the brand, but there are more expensive silicones - Table 1.

Table 1. Popular brands of silicone adhesives and the average market value of goods

There are a lot of silicone glues, among the products one can note the popular compositions Avtohermesil, Pentelast, Remontik, Penosil.

When choosing glue, you need to pay attention to the technical characteristics of the composition and the period of its use. Market value depends on the chemical formula of the adhesive product, volume and manufacturing company.

Silicone Glue - Description

What is silicone? It is an organosilicon high-strength polymer, a chemical compound of high molecular weight type. In appearance, liquid silicone looks like resin; synthetic rubber is used to create it. It was invented in the middle of the XX century, now it is used very widely. The most popular products based on it are glue and sealant. In the manufacture of adhesives, in addition to silicone, other substances are used, called target additives, fillers.

What can be glued with this tool, where is it used? Composition with silicone is perfect for gluing:

• ceramics
• metal
• plastics
• rubber
• glass products
• paper
• aluminum
• tile

The scope of use of silicone is so wide that it is impossible to list all directions. In industry, dishes are made from it, kitchen utensils, for example, sets of baking dishes, pastry bags. Silicone can seal bathtubs, window glazing, it is indispensable in cosmetology, medicine.

Actually silicone adhesives are used to repair equipment, electronics, radio products, for crafts. But the most popular tool in everyday life, at a construction site, for repairing premises, especially where increased moisture resistance of materials is needed.

The difference between glue and sealant

There is no significant difference between the means, so sometimes glue is referred to as glue-sealant. Characteristics, price, basic composition are also similar. But next to additives and texture, they can vary. Usually the sealant is thicker, the glue is flowing. There are differences in the form of release, type of bottle, nozzle, because each material has its own purpose. Glues are usually packaged in small tubes, they can be applied without a gun. To work with sealant you need a construction gun.

Sealing joints that are long, sealing windows, pipes, walls, structures made of plastic, glass is carried out using sealant. But gluing of tile masonry, gluing of corners, dishes, shoes, applying to a self-adhesive adhesive tape for a bath is carried out by glue.

Composition and properties of glue

Up to ½ of the composition of the material is represented by artificial rubber. Most builders prefer to use clear glue, but there are white, black, and even brighter shades on sale, depending on need. According to GOST, the tool may include other components:

• plasticizers
• extenders
• fungicides, antiseptics,
• catalysts (curing accelerators),
• thixotropic additives.

Most home care products are sold as a one-part formulation. Only a number of professional adhesives are sold as two-component complete with a hardener. Due to the properties of silicone, the adhesive joint after hardening becomes frost-resistant - it retains its quality even in cold temperatures (up to -40 degrees). Also, the resistance of the seam is high with high temperature exposure - up to +200 degrees.

On sale there are a number of compositions for use at higher, lower temperatures (extreme). At what temperature the material melts, it is indicated on the package. Some have a melting point above 300-400 degrees.

Silicone adhesives are waterproof, this ability allows you to reliably seal dishes, aquariums, apply to glass. The adhesive is minimally electrically conductive, rather, it can be called an isolate - it almost does not conduct electric current. Other weld properties:

• fortress,
• elasticity,
• resistance to UV rays, radiation,
• long preservation of color, transparency,
• repulsion of dust, dirt,
• lack of oxidation.

Only high-quality glue is truly moisture resistant, has the other listed properties. If the manufacturer included cheap silicone, poor plasticizers in the composition, the service life can be reduced several times. It is convenient to use silicone material, it is moderately thick, while flowing into the smallest pits, cracks. The product is non-toxic, safe for humans, unlike the popular Moment glue from Henkel. Skills for gluing products are not required, the work is very simple. The material dries quite quickly.

Work with glue

How to use silicone adhesive? Difficulties with the repair of various products will not arise, even a beginner will cope. But labor efficiency will depend on the quality of foundation preparation. It is important that the base is dry, clean, smooth. It must be degreased before work, this will help improve the quality of adhesion. It is possible to degrease the surface using any suitable means - washing solution, special composition. After degreasing and drying, the edges of the joints can be pasted over with paper tape, so that flaws, blots can be avoided, the layer will be applied evenly.

Further, the procedure is as follows:

• cut off the nozzle of the glue, if it is sold in a small tube, or open the cap (it is better to use a special dispenser for glues, it will not allow excess funds to come out),
• when working on a large area, you should buy a glue gun,
• apply the material to one of the fastened surfaces and fix them or lay an adhesive seam,
• surfaces must adhere in 10-30 minutes, as indicated in the instructions,
• You can fully operate the product after a day, during this period polymerization will occur.

An increase in room temperature by 5 degrees from room temperature accelerates polymerization by half. The thickness of the adhesive layer of more than 20 mm does not make sense, since in the depth of the seam, the product will not harden. Excess glue should be removed immediately with a cloth or spatula.

Popular brands and price

The cost of funds is usually in the range of 200-500 rubles per package of 330-500 ml, the price depends heavily on the manufacturer. Glue in a package of 10-30 ml is much cheaper - in the range of 20-100 rubles.

The following are well-known brands sold in stores:

1. RTV 118Q. It is a food glue that can come in contact with food and not cause harm to health. It is used mainly for gluing utensils, ceramics, in everyday life it is useful for repairing remotes and other rubber products. Withstands temperatures up to +260 degrees.
2. Jaba. An excellent tool for aquariums, harmless to living creatures, plants. You can glue glass, ceramics, seal small leaks.
3. Loctite 5699 Neutral Gray. It is used for the manufacture of gaskets, they can stick hard flange bases, seal molded cases, vehicle transmissions.
4. Pentelast 1143 Multifunctional acid glue, has exceptional strength, is suitable for all materials except metal.
5. DoneDeal. Heat-resistant silicone adhesive sealant, used in car repair, withstands vibration, high temperatures, humidity, chemicals.
6. "Autohermesil." Oil-resistant, water-resistant glue, sold in volumes of 70-160 g and 5-8 kg. Used for gas tank, engine, bodywork, radiators, can be used in the cooling system.

With careful use of the products, the glue line will last for many years, but, if necessary, it can always be replaced with a new layer of the product.

Types of sealants

Depending on the type of main substance, sealants are divided into:

• acrylic
• polyurethane
• silicone
• bituminous
• thiocol (polysulfide).

According to their readiness for use, one-component adhesive sealants and two-component compositions are distinguished. The characteristics of the sealants are determined by the adhesive and additives that give the composition additional properties: elasticity, water, frost and others.

Acrylic Sealants

The basis of acrylic sealants is polymethyl methacrylate, a durable transparent plastic from which plexiglass is made. Acrylate microparticles are mixed with water, thickeners, fillers, plasticizers are added, and glue is obtained. When it dries, an inelastic layer forms.

Advantages of acrylic sealants:

• do not crack during vibrations,
• do not crumble and do not change color from sunlight,
• do not contain harmful substances
• stick to concrete, brick, plastic, glass, metal, wood,
• don't burn
• harden in 0.5 - 1.5 hours.

• burst if the seam width changes,
• they sit down and pass water over time.

These disadvantages are more inherent in adhesives without additives. The reason is that hardened acrylate is not elastic, it does not stretch. When a bathtub is filled with water or a person sits in it, it can move slightly. The width of the seam changes, the sealant cracks. If you seal the joints of a leaking aquarium with such acrylic, the seam will settle, and microcracks will appear between it and the glass, through which water will leak.

The movable slots are sealed with acrylic sealants with increased elasticity. Produce compounds that can hold in the seams between the panels of multi-storey buildings. The hardened layer in them stretches like rubber, does not burst if the seam increases.

Acrylic Sealant Accent 124, elastic, 5 L - 1 292.60 rub., Oliva online store.

Acrylic sealants are suitable if necessary:

• close up cracks in wooden, brick and concrete walls from the inside of the premises,
• fill the voids between the doorposts and the walls,
• waterproof pipe joints,
• stick ceiling tiles and skirting boards,
• repair cracks in furniture, parquet and wooden floor boards,
• seal the joints of the laminate.

Acrylic sealants paint, varnish, water-based. Pre-treated with an acrylic primer so that the paint or varnish adheres more firmly.

Sealant Krass universal acrylic, 300 ml - 97.90 rubles., Bafus online store.

They produce transparent and white sealants, compositions that mimic the color of wood of various species, for exterior and interior use, are frost and moisture resistant.However, the moisture resistance of acrylic is relative: it will not “float” if it is poured with water, but if it is in constant contact with water, it will miss it due to shrinkage.

Sealant for wood Accent 125, a bucket of 5 l, color of wenge - 1 952,30 rub., Online store "Oliva".

Sealant acrylic frost-resistant Tytan white, 310 ml - 140 rub., Polysynthesis online store.

Choosing an acrylic sealant, take into account the scope. Particular attention is paid to elasticity, so as not to use the composition where it is cracked. This information is indicated on the packaging.

Polyurethane Sealants

Polyurethane is a synthetic material. Depending on the ratio of the components, it can be hard, like wood, elastic, like rubber, porous, like polystyrene. Shells, bathtubs, pipes, heaters, mounting foam are made from it, added to paints and varnishes.

Polyurethane sealants differ from acrylic in the elasticity of the seam. It stretches when the gap grows, and contracts if it decreases.

Other advantages of polyurethane sealants:

• do not react to acids and alkalis,
• do not collapse upon impact,
• do not wear out when walking,
• do not change properties in the temperature range from - 60 ° С to +80 ° С,
• stick to plastics, steel, aluminum, glass, wood, concrete, brick, stone,
• don't sit down
• not afraid of the sun, moisture and temperature changes,
• harden in 3 to 4 hours.

The disadvantages include the vinegar smell of acid variants, slow (up to several days) solidification at temperatures close to 0 ° C, poor adhesion to plastics.

Produce one-component and two-component sealants. Unicomponent is applied at temperatures from +5 ° C to +30 ° C. At lower and higher temperatures, they lose their elasticity and strength, as they freeze with the participation of moisture, which is not enough in the air in hot weather and in the cold.

Sealant polyurethane one-component Rabberflex Pro PU-25, 600 ml - 375 rubles., Online store "Building materials".

Two-component adhesives consist of working paste and hardener. They do not need moisture to freeze. Therefore, they work with them at sub-zero temperatures, and in the heat.

Sealant polyurethane two-component Sazilast 24 Classic, 6.6 kg - 1,300 rubles., Online store "StroyMat 77".

They produce transparent, white, gray, brown, black sealants. Polyurethane compounds are used when necessary:

• close up cracks in window sills, door and window openings,
• pour the seams between the tiles of natural and artificial stone,
• fill the voids between the timber of the wooden log house inside and out,
• waterproof the foundation, roof or man-made pond in the garden,
• insulate metal pipes,

Polyurethane sealants are economical, therefore they are used when there are many gaps and voids. Choose taking into account the information on the package. Looking for information about the scope.

Silicone sealants

Silicone sealants are considered universal because, depending on the components, their properties satisfy most of the needs of customers.

The composition of silicone adhesives is divided into neutral and acidic. Neutral formulations contain alcohol or its distant relative ketoxime. Adhere to glass, plastics, concrete, brick, glass. But exfoliate with high humidity.

Neutral Silicone Sealant Moment Germent, 280 ml - 355 rub., Kronto online store.

Acetic acid is added to acidic sealants. With its help, adhesive molecules are firmly bonded. The glue becomes resistant to moisture and high temperatures. Acid sealants marked “sanitary” seal the joints of sewer pipes and plumbing fixtures with walls and floors.

Silicone Sealant Sanitary (Acidic) Iso Chemicals Isosil S105, 280 ml - 153 rub., Bafus online store.

Silicone is the best sealant for sealing joints in toilets and bathrooms. But it is not used on materials sensitive to acids: non-ferrous metals, marble, lime plasters. Silicone compounds are cheaper than neutral ones.

Universal silicone sealant Profilyuks colorless, acid, 300 ml - 263 rubles., All Tools online store.

Advantages of silicone sealants:

• form a strong elastic layer,
• withstand temperatures up to 350 ºС,
• prevent mold and mildew,
• Do not fade or collapse in the sun.

The disadvantages include restrictions for certain species: neutral moisture sensitivity, incompatibility with some acidic materials. In addition, both types of gluing poorly connect narrow PVC profiles and corners, so they are not used for gluing corners and connecting profiles in a PVC lining.

Silicone sealants are used if necessary:

• close up joints in drywall constructions,
• fill voids under kitchen countertops, window sills made of artificial or natural stone,
• stick a mirror
• repair the aquarium
• fill the seams between the bathroom and the walls,
• seal joints and threaded pipe joints.

Acid sealants are more elastic and stronger than neutral ones, but not by much. At the same time, the price is lower by about 10%. Acid is more profitable for large volumes of work.

Bitumen sealants

Bitumen is a product of oil refining. Modified bitumen, which is characterized by increased elasticity, is added to the sealants. Bituminous sealants are superior in strength to acrylic, polyurethane and silicone. They adhere to wood, concrete, metals, concrete and plastics.

However, bitumen emits volatile substances harmful to health, so it is not used inside residential premises. Bituminous sealants are used for waterproofing metal and slate roofs, cellars and for protection against rust of metal pipes laid outside the apartment.

Bitumen sealant is a sealant for outdoor applications.

There are bitumen and bitumen-rubber sealants. The second is distinguished by the fact that they can be applied to wet surfaces.

Sealant bituminous KRAFTOOL 41261, 300 ml - 235 rubles., 220 Volt online store.

Tytan Professional bitumen-rubber sealant for roofing, 310 ml - 250 rub., World of Colors online store.

Bituminous sealants are selected based on where it will be used. A sealant with aluminum powder, which gives the composition a metallic color, will be less noticeable on galvanized iron roofs. If narrow seams are applied, buy glue in tubes. In large areas, it is convenient to work with glue packaged in buckets.

Thiokol Sealants

Liquid thiocol is a resin similar in properties to rubber. Thiokol sealants are the most durable of all sealants, but also the most expensive.

• not afraid of moisture, sun, frost,
• do not react with acids, alkalis, solvents, gasoline and technical oils,
• mate with metals, wood, concrete, brick,
• serve up to 50 years,
• Do not shrink.

• poisonous fumes are emitted in liquid form, therefore they work with them in gloves, respirators and goggles,
• destroy plastics.

Thiocol sealants are two-component compounds that are mixed before starting work. The mixture retains properties for no more than two hours. Did not have time to use - you can throw it away.

Sealant thiokol Sazilast 51, two-component, 15.4 kg - 4990 rubles., Master online store.

Thiokol sealants are not taken for work in the apartment, because you can find suitable options for cheaper. But for a garage or workshop where they deal with aggressive chemical fluids, it is optimal. Once sealed the cracks and joints, missed the roof and forgot about waterproofing forever.

How to choose a sealant

Before you buy sealant, carefully read the information on the package. First of all, they are looking for information about the composition, scope and materials with which the adhesive adheres.

Product quality is also important. If there is an inscription “ISO 11600”, then the sealant is certified according to the international standard. This is a high quality mark. But the abbreviations "ISO 9001" or "ISO 9002" characterize the certification of production, not products. They guarantee that all batches of goods have the same quality, but do not say anything about its level.

The scope of the sealant depends on the hardness of the layer. Hardness is indicated on the packaging in units of the Shore scale:

• 15 units - for joints in the log house, joints between panels, gluing plastic parts,
• 25 units - for joints in a humid environment and glass,
• 40 units - for repair of concrete and reinforced concrete structures,
• 50 units - to eliminate cracks and voids in the metal.

Shore hardness is indicated on the packages. If it’s not there, look for information about the scope.

The choice of glue depends on the mobility of the gap, which must be repaired. If it gradually expands, use elastic adhesives.

The optimal sealants for various types of work are shown in the table:

The same work can be done with different compositions. When choosing a sealant, check the characteristics: they should not be redundant for the selected work, so as not to overpay for unnecessary qualities.

If you are afraid that you will not be able to choose a sealant yourself or use it correctly, contact a professional. Read reviews about companies, invite a master - he will say that it is better to buy, and will do all the work for you.

Classification of silicone sealants

Available in the form of one-component and two-component compositions. The first group of sealants is a completely ready-to-use composition, does not require any additional manipulations, curing occurs when interacting with air and moisture. The polymerization of the second group occurs exclusively with the participation of the catalyst.

Two-component compositions are widely used in industry. In domestic needs, repairing, sealing plumbing equipment, swimming pools, joining various surfaces in rooms with high humidity, silicone one-component sealants are most widely used, which, in turn, are divided into subspecies such as acidic and neutral.

One-component silicone moisture resistant sealants

Acid Compounds produced on the basis of acetic acid, emit a characteristic smell of vinegar during the hardening process. They have a low cost, are marked on the packaging with the letter "A". The main disadvantage of acidic sealants is incompatibility with almost all non-ferrous metals, when interacting with which they cause an accelerated corrosion process, as well as with marble and cement-containing materials.

Neutral Compounds are made using ketoxime or alcohol. Replacing acetic acid with these components eliminates the disadvantages of acidic silicone sealants. Thus, this material can be used with marble, and with metal, and with cement substrates. However, choosing this type of sealant, it should be borne in mind that its cost is higher than that of acidic ones.

How to apply silicone moisture-proof sealant?

So that the material does not lose elasticity and does not crack, it is necessary to work with it in compliance with the correct sequence of work:

1. Foundation preparation. The surface is cleaned of rust, dirt, dust, degreased and sanded. Old sealant, if present, is removed.
2. Carrying out sealing. The cartridge is inserted into the mounting gun. By pulling the trigger, the seam is carefully processed so that the line formed is continuous.
3. Seam. The seam can be formed five minutes after applying the sealant. This can be done with a spatula dipped in soapy water or with your hands. If the latter option is chosen, you need to work in rubber gloves to avoid direct skin contact with the substance.
4. Treatment. Excess sealant protruding beyond the seam is removed with paper or a damp cloth.

You can edit the connection for the first 20 minutes. After this time, touching the joints is not recommended. In order not to have to clean the silicone, the adjacent surfaces are covered with masking tape, which is removed at the end of the work.

Drying time for silicone-based adhesive sealant

It depends on many factors, including the type of composition used. Acid sealants dry from four to six hours, while neutral sealants dry for about a day at temperatures from +5 to +40 degrees Celsius.

Curing of the composition to form a thin protective film occurs within 15-20 minutes. The onset of complete hardening takes much longer. On average, a 2 mm layer dries up per day. The thicker it is, the longer the composition will dry.

The adhesion of the material depends on the quality of the processed surface. If it is not prepared, it increases the likelihood that the sealant will dry separately from the base.

Equally important is the composition of the adhesive sealant. With an increase in the number of fillers, the hardening and shrinkage times increase. For each silicone system, the manufacturer issues a card with technical data, which indicates the approximate setting and hardening times.

How and with what to wash silicone sealant?

• Removing silicone-based adhesive sealant is easiest at the application stage. This can be done with a normal damp cloth, without using any additional funds. There are many ways to get rid of dried silicone:
• White Spirit. Promotes easy and quick cleaning of the composition, but can damage the surface, for example, wipe not only silicone sealant, but also paint.
• Penta-840. A special tool called a “solvent for silicone” that can clean any surface. It is represented by several species, selected according to the type of material for purification.
• The usual knife. The tool must have a sharp blade and must be handled carefully so as not to scratch the decorative surface. After removing the glue, wipe the base with a dry cloth.
• Vinegar and alcohol. The first is used for acidic silicone sealants, the second - neutral.

If gentle removal methods did not help, resort to the help of crevices. They are sold in hardware stores. You need to work with them in goggles, gloves, an apron to prevent the ingress of aggressive substances on the skin and mucous membranes.

Dry sealant removal

Washes and solvents, even for special purposes, do not always cope with the task of cleaning surfaces. Aggressive compounds can not only remove the sealant layer, but also damage the base underneath. More gentle can be useless.

To avoid adverse effects, the solvent is first tested by application to a small area. If, after washing, the base remains intact, boldly switch to the use of substances in visible areas.

The most effective is mechanical removal.Cured sealant is cut off from hard surfaces. For soft surfaces, it is recommended to use a plastic or wooden scraper. When the silicone is cut off, the area is wiped with a dry, clean cloth.

The nuances of the right choice of moisture-resistant silicone

Compliance with the technology for applying the composition is not enough. Not all silicone sealants available on the market meet the stated qualities and characteristics.

So that the result of working with silicone moisture-proof sealant does not bring disappointment, when buying it, pay attention to five important criteria:

1. Production date. Even the highest-quality composition with an expired shelf life loses all its operational characteristics.
2. Packaging. The presence of a small crack and other defects that violate the integrity of the sealant packaging leads to the fact that the composition hardens and dries. This makes it unusable.
3. Purpose of use. Acquisition of adhesive sealant that does not meet the intended purpose will result in cracking and blackening under unsuitable conditions.
4. Manufacturer. Give preference to better trusted brands, which do not contain cheap impurities that degrade product quality.
5. Place of purchase. The chances of acquiring expired or low-quality products are several times less if you turn to a large construction store, and not to the market.

Sealant quality

To reduce the cost, unscrupulous manufacturers dilute sealants with cheap acidic, organic, oily and other solvents. It is impossible to find out if the sealant is “diluted”. There are no strict requirements for product labeling and the inscription “100% silicone” cannot be regarded as true.

A decrease in the content of the silicone base leads to a partial loss of quality. Glue-sealant produced in violation of the technology gives greater shrinkage, is short-lived, has less adhesion, ductility and water resistance. There are compounds that are not just poor quality, but do not dry out at all. And the desire to save on the acquisition of a sealing moisture-proof silicone composition of dubious origin of inevitable will lead to even greater expenses.

You need to purchase products from such well-known brands as “Moment”, “Ceresit”, “Tytan”, “Silka”, “Soudal”, “Denbraven”. The list of bona fide manufacturers is not limited to these brands. The main thing is to make a purchase at a reputable large retail outlet, valuing its reputation, offering only high-quality products.

Color or transparent

It is impossible to paint silicone moisture-proof sealant on your own. If you need to use a composition that should not differ in color from adjacent to the joints, cracks, seams of the surfaces, you need to purchase immediately painted material.

The tint is given by the addition of fillers - coloring pigments. They, like any other additives, affect the quality of the final product. If their content is large, this can negatively affect the result. More practical and versatile are transparent formulations.

When the shade is not critical, it is better to get transparent. In other cases, you will need to carefully read the composition.

Sealant Consumption

The elasticity and extensibility of silicone moisture-resistant sealant glue is due to the nature of the interaction with the clinging surface. To maintain maximum performance of these properties, it is necessary that the composition adheres exclusively to abutting surfaces.

Adhesion of material to the back of the seam can lead to mechanical rupture. Avoid this by laying the sealing cord. Its use allows you to close deep gaps, significantly reduce the consumption of sealant. To obtain maximum savings in the composition allows the use of a mounting gun.

The amount of material required depends on the depth and width of the seam. These indicators are multiplied among themselves. The final number is the consumption of the sealant in milligrams per linear meter of the weld being processed. If you close the slots of a triangular shape, then the resulting value is divided into two. One standard cartridge lasts for 6 meters of a seam with a depth of 5 and a width of 10 mm.

General recommendations

In order for the seam to be of high quality, and the result is fully consistent with all presented to areas subject to increased moisture, three important nuances must be observed:

1. acquire only quality material,
2. comply with the technology of proper application,
3. use a composition that is fully consistent with the goals.

An equally important factor is the choice of application form. Standard packaging requires the use of a mounting gun, but allows you to control the thickness of the seam, work with hard to reach places.