Which glue is best for wooden products. Moisture-resistant wood glue – what to choose. Liquid polyurethane glue

One of the most controversial materials, about which even experts do not have a clear opinion, iswood glue: which one is better, more reliable and easier to use? The question is very interesting, requiring knowledge of the features and properties different types glue.

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What is it needed for

Wood glue is used everywhere and constantly. Everyone at least once in their life has glued some wooden parts together or repaired broken things or pieces of furniture.Wood gluingproduced by slightly different methods than joining, for example, rubber or plastic products. There is no need to perform standard operations: applying the composition, drying for about 10-15 minutes and firmly pressing the parts against each other.

Wood requires a different approach, which is determined by the structure of the material and the individual properties of each species. It requires a different adhesive composition that can be absorbed into the material and create a durable film. Currently, many compounds have been created, from ancient traditional wood glues to the most modern synthetic compounds. Question,how to glue wood, not at all simple.

Varieties

Wood gluing materials have different composition and purpose.

Some of them are universal; joining wooden parts is just one of their many uses.

Others are intended only for gluing wood and have no other uses.

Choosing how to glue wood to wood, you should decide on the type of composition and its properties, which should be discussed separately:

PVA

One of the most common compositions, familiar to everyone since school days. Polyvinyl acetate dispersion, as this composition is correctly called, can be used for gluing paper, wood and other materials. The main condition is the ability of the bonded material to absorb moisture. It has the appearance of a milky-white thick liquid. When dry it becomes transparent. Mostly, PVA glue is used for gluing wood , since it is very convenient for this. Its features:

• Available in ready-to-eat form;
• dries quite quickly;
• does not stain the gluing, the glue squeezed out when squeezing the parts can be removed without consequences;
• diluted with water; any glue that gets onto a clean surface can be easily washed off or wiped off with a damp cloth.

There are different brands of PVA glue designed for construction work, universal or carpentry compounds. Setting time is about 20 minutes (depending on the brand), complete drying is 24 hours.

Attention!If PVA glue was stored in unheated room and frozen, then after thawing it cannot be used.

Epoxy

This is a two-component composition consisting of epoxy resin and hardener. When mixed in the right proportion, the material hardens into a strong solid mass.

The curing process of the composition is purely chemical in nature, so the presence of air is not required for this.

It is noteworthy that epoxy adhesive not intended exclusively for wood , it can glue different different materials that do not have chemical contradictions with the adhesive components.

For him it has important correct dosage of components when mixing: if there is too much hardener, the mixture “boils”, bubbles and quickly turns into a solid foamy mass. If there is a lack of hardener, the mass does not gain the required strength. The hardening time for different brands can vary from several minutes to one day, most often - several hours.

Epoxy glue prices

epoxy adhesive

BF

BF glue appeared in wide use in the late 70s and early 80s of the last century. It was believed that this was the most universal and reliable composition, capable of tightly connecting anything. In fact, this is not the case; the material has a lot of restrictions or conditions for use.Designed for gluing metals to non-metals, plastics and other materials.Wood is not exactly absent from this list, but it is far from being in first place. However, if neededwood glue, waterproof and frost-resistant, then the BF-2 or BF-4 brands fully correspond to this definition. The gluing technology is quite inconvenient: it requires applying an adhesive layer, drying it “tack-free” and compressing the parts for a while to gain strength of the adhesive layer.

Heat-resistant compounds

Wood in its own way technical properties not subject to heat treatment. Therefore, specialized adhesive thermal compositions for gluing wooden products simply doesn't exist, but some types of heat-resistant compounds can be used for these purposes.

Exist different kinds such compositions. These can be synthetic mixtures, various modified varieties of epoxy glue.

This group can include a special material produced in the form of rods, which is applied using an adhesive gun. The material, melted to a liquid state, is applied to the surface to be glued and pressed tightly against the second part. This method is simple and convenient, but requires the constant purchase of adhesive rods and connection to the power supply.

Carpentry

Carpentry (gluten) glues are one of the oldest groups, used back in ancient times. In our timewood glueused primarily for restoration of antique furniture or repair of acoustic musical instruments. The reason for this limited use is the difficulty of working with wood glues, which are sold dry and require preparation for use.

There are several types of wood glues:

• bone;
• fleshy;
• sturgeon.

The first two are made from horn plates or animal skins, the latter is made from the skin of sturgeon fish. It is believed that the bone composition is better than the flesh one, but sturgeon is very difficult to find; it is used mainly by violin or guitar makers.

Important!The main feature of wood glue is its reversibility. The glue can be soaked in hot water, pulled apart for repairs, and put back together without causing damage to the material of the part.

Prices for wood glue

wood glue

Syndeticone

Syndeticoneglue for gluing wood to wood- modification of wood glue, invented in 1878.

Since then, this composition has been widely used for a long time, but today its use is almost complete.

It is noteworthy that the name of the glue does not indicate any original composition, it is only a reference to the original name of the glue - “Syndeticon”, as the inventor called it.

The composition includes the following components:

• wood glue;
• sugar;
• slaked lime.

Its production takes about a day, which was also the reason for refusing to use it.

Polyurethane

Polyurethane wood gluedistinguished by high performance qualities and high cost. The composition is suitable for gluing wet wood, can be used for both interior and exterior work. The glue foams when it dries, filling possible cavities and stopping moisture or cold from reaching them. The adhesive joint can be used at temperatures from -30° to + 100°, in addition, polyurethane is the bestwaterproof wood glue.

Casein

Another very old one natural composition. Its main component is casein, a milk protein obtained from low-fat cottage cheese. Available in the form of granules from brown to white- the higher the quality, the lighter the granules.

The material is truly universal - in addition to gluing wood, it is used in manufacturing, painting, and printing.

Traditionally used as environmentally friendly furniture glue high class. At the same time, the surfaces to be glued must be protected from the glue getting on the front parts of the parts, since it is quickly and deeply absorbed, leaving dark spots. In addition, the material is hygroscopic and can deteriorate: become moldy, and there is a possibility of insects appearing. It must be stored in a tightly closed container.

Prices for casein glue

casein glue

Pasty

Paste-like adhesives are used to join poorly formed parts. Thick material fills small voids like putty, sealing the seam and stopping the access of moisture, cold or other unwanted influences. Typically, wood gluing is not one of the main specializations of such compounds, but for uneven surfaces this choice is quite justified.

Basic properties

Good glue for wood it must have a number of specific qualities:

• strength;
• resistance to water;
• good adhesion to any type of wood;
• non-toxic composition;
• versatility of use;
• high drying speed;
• the composition must be sold ready-to-use;

Many modern compositions have such properties, for example,wood glue "Joiner". Most traditional adhesive compositions, for all their advantages, require too long and labor-intensive preparation, which makes work inconvenient and reduces productivity.

When choosing wood glue, you should pay attention to some points:

1. If gluing is permanent, then it is best to use some kind of synthetic irreversible compound. To connect parts that can later be disassembled, for example, musical instruments, it is better to choose traditional types - bone, casein and the like.
2. When gluing light wood, you should not use casein glue. The seams will darken and the work will look sloppy. The best choice- “Joiner” glue, which, when dried, becomes approximately the same color as the wood.
3. When buying PVA glue, pay attention to its consistency. If there is a separation of the material into more liquid and thicker fractions, it means that the glue was frozen during storage or transportation. Such material cannot be used, it has lost its qualities.

Homemade recipes for preparing the composition

Some traditional types glue can be prepared independently, at home:

• Casein glue is made from low-fat cottage cheese, which is soaked in soda solution and washed under running water. Then the mass is dried to a dry powder, which is diluted with water immediately before use.
• Sometimes an ordinary paste helps to get out of the situation. It is brewed from flour (6 tablespoons per 1 liter of water) by adding an aqueous solution of flour to boiling water. The mixture is brought to a boil, cooled and used for its intended purpose.
• Wood glue is made in a water bath: in a container placed in a container with hot water, heated on a tile. Ready-made wood glue has a liquid and flowing consistency and is used asfurniture wood glue.

Important!Wood glue has a strong, stale smell, sometimes even too strong. Before preparing it, you should consider whether to use a ready-made composition.

General gluing rules

Each type of glue has its own specific methods of use. TO general rules This may include the need to clean and dry the surfaces to be glued, and first do a dry assembly without glue to check the accuracy of the fit. If the parts cannot be pressed together with a little manual effort, then you need to put off gluing and fit them better. The connected parts are pressed and fixed with clamps until the glue dries completely (usually it is recommended to keep them for 24 hours).

Using glue to join wood pieces is an oldie, but a good one. efficient technology. Modern synthetic compounds can greatly enhance the strength and stability of the joint, ensuring high-quality service of the glued parts.

During the repair work In the house you often have to deal with the need to glue parts or structures made of wood. You can, of course, combine them and mechanically using screws, self-tapping screws, overlays. But it is adhesive joints, being practically invisible, that make it possible to preserve the beauty of wood and products made from it. Sometimes you need to glue wooden parts to structures made of other materials.

For each individual case, it is necessary to select an adhesive that will reliably connect the parts and will serve for a long time.

Until the beginning of the 20th century, glues of plant and animal origin were mainly used for gluing wood. The emergence of the plywood industry was the reason for the development synthetic species glue. Currently, the range of such adhesives is very wide, as is the scope of their application.

All wood adhesives can be divided according to several criteria:

• by origin;
• by composition;
• by water resistance;
• by appearance;
• by method of receipt;
• in relation to heat;
• by type of solvent.

Based on their origin, adhesives are divided into the following types:

• plant origin - nitrocellulose, dextrin, starch;
• animal origin - fish, bone, flesh, casein, albumin;
• synthetic adhesives;
• mineral adhesives – cement, silicate, bitumen.

Based on their composition, all adhesives are divided into single- and multi-component.

By water resistance:

• low degree of water resistance - for use in enclosed spaces;
• medium water resistance - can be used in outdoor structures protected from direct exposure to the atmosphere;
• high water resistance - serve for a long time in external atmosphere conditions.

Based on their appearance, adhesives are divided into granular, powder, paste, film, and liquid. By production method (only synthetic adhesives are divided): · polymerization adhesives; polycondensation

In relation to heat, adhesives are also divided into 2 types:

• thermoplastic - when heated, they melt and remain in a liquid state, and when cooled they harden again;
• thermosetting - when heated, they first melt and then finally harden.

By type of solvent:

• with organic solvents;
• alcohol- and water-soluble.

Currently, adhesives of natural origin have largely given way to synthetic products, which are characterized by their low cost, wide availability of non-food raw materials, and the ability to regulate their properties. glue mixture, low glue consumption and high curing speed.

But in cases where high demands are placed on wooden products and structures in terms of environmental friendliness, there is simply no alternative to natural adhesives.

Modern adhesives have many requirements, some of which may contradict each other.

Operational requirements:

• the glue must connect well and reliably hold the glued parts;
• adhesive joints must have acceptable water resistance and weather resistance;
• the adhesive seam must be durable.

The economic requirements are as follows:

• the cost of raw materials for the production of glue should be low;
• the glue must have low consumption;
• The glue production process should be as simple as possible.

Technological requirements:

• optimal glue viscosity after preparation;
• sufficiently long viability of the composition after the introduction of the hardener;
• high curing speed;
• long shelf life of the glue.

Environmental requirements: low corrosion hazard of the glue, non-toxicity of the components included in its composition. Special requirements: oil and petrol resistance of the glue, transparency of the adhesive seam and some other specific requirements.

The most common types of wood adhesives

Some types of adhesives are used exclusively for the needs of industrial production of wood products. Therefore, we will consider only those compositions that are most often used in everyday life for repairing furniture or other wood products.

Popular adhesives:

• Wood glue is made from animal skins and bones. In former times, this glue was widely used in the production of furniture and in wood processing plants. Nowadays it is rarely used both in industry and in everyday life. Wood glue is usually sold in the form of granules that need to be dissolved in water when heated. You can also find a jelly-like mass on sale, which you simply need to dilute with water to the desired consistency.
• Syndeticone glue - prepared on the basis of a composition identical to wood glue, but powdered sugar and slaked lime are added to it. Provides high strength adhesive joints, resistant to moisture and aggressive chemicals. The downside is the cooking time - the dry mass must be kept in water for at least 24 hours.
• Glue paste - also prepared on the basis of wood glue by introducing crushed wood ash or chalk into the hot mass. It is used not only for gluing, but also for priming and puttying wooden parts. It also holds stone, glass, and metal together well.
• Compositions based on animal fats. They are used when there are high requirements for glue safety. The most popular among these glues is casein - it reliably holds together wooden, paper, fabric and leather surfaces. Casein glue is sold in powder form, which must be mixed with water and brought to the consistency of sour cream. 5 minutes after applying the glue, it dries almost completely and holds the parts together. Then the surfaces to be glued need to be pressed even more tightly against each other. The disadvantage of glue is that it stains the parts, so you need to apply it as carefully as possible.
• PVA glue is inexpensive and well known. The glue contains no toxic substances, so it is widely used for home renovation. It is also good because PVA can be stored for a very long time in a well-closed container. The glue hardens as moisture is absorbed into the surface and evaporates. The glue is not very water resistant. Therefore, in conditions high humidity It is better to use thick yellow PVA, which lends itself well to sanding.

• Resorcinol glue. It is used for gluing elements located outdoors, as it has excellent resistance to atmospheric influences. The glue is two-component - formaldehyde resin and hardener. The components can be sold both in powder and liquid form. The glue is able to set quickly at temperatures above +15 degrees. After curing, it forms dark brown joints, so it is not recommended for gluing light wood.
• Urea-formaldehyde glue. It is most often sold in powder form, which must be mixed with water. Sometimes glue is sold complete with a hardener. Then one part is treated with glue, and a hardener is applied to the second. The usual composition is applied to both elements being glued, while it perfectly fills the gaps and hardens very quickly. Additionally, the parts can be compressed, this will speed up setting. The glue is toxic. Therefore, you need to work with gloves, goggles and a respirator, and the room must have good ventilation.
• Epoxy adhesive is two-component. This composition is almost universal, forms a strong connection between parts, is resistant to water, fuels and lubricants and even some aggressive substances. Dries after 24 hours. The disadvantages include the need to protect the skin when working with glue, as well as its increased consumption.
• BF adhesives - compositions BF-2 and BF-4 are used for wood: BF-2 is used for interior work, and BF-4 for external ones. The glue must be applied in 2 layers, the interval between applications is 15 minutes. Glue dries when normal conditions occurs within 1 hour. Both compositions have good moisture resistance, and BF-4 can also be used at low temperatures.
• Polyurethane adhesive is quite expensive compared to other types of adhesives, but it is of high quality. The adhesive joint is able to withstand high dynamic loads, is not susceptible to temperature changes, high humidity, ultraviolet. This glue should be used for products intended for use in adverse conditions.

• Heat resistant adhesive. Sold in the form of rods, when applied they require the use of a special “gun”. Most often used when sealing cracks in wooden structures and fastening small parts. Such adhesive joints are resistant to high temperatures.

How to choose the right glue

In order to receive good result, you need to purchase a composition that best suits your tasks.

When choosing, you need to focus on the following considerations:

• The opinion of a person who has extensive experience in such work.
• Scope of work and its specifics (type of parts to be glued, location and conditions of their further operation). For large volumes, it would be more appropriate to use powder adhesives, as they are inexpensive.
• Select the composition that is most suitable in terms of physical and chemical properties and the characteristics of wooden products or structures.
• Study the adhesive specifications on the label and become familiar with how to use it.
• Give preference to glue from a well-known manufacturer, intended specifically for wood, rather than a universal composition. Among the most popular modern adhesives are brands such as Kleiberit, Casco, Titebond, and Moment-Stolyar.

The water resistance class of the adhesive is indicated by the letter D and the numbers behind it:

• 2 – the water resistance of the composition is low;
• 3 – sufficient;
• 4 – high.

The higher the degree of moisture resistance, the more expensive the glue.

Therefore, you should not purchase a composition marked D4 for products used under normal conditions.

Before carrying out work, the wood must be prepared:

• It is necessary to select parts that are similar in texture and color, and to reject elements with cracks, damage, or protruding knots.
• The parts need to be cleaned and treated so that the pores of the wood are exposed and the adhesive can penetrate deeply into the wood.
• The humidity of the parts to be glued should be no higher than 12-18%.

Gluing process:

• Most often, the adhesive composition is applied evenly to both workpieces. The thickness of the layer depends on the type of glue and its consistency.
• According to the instructions included with the composition, you may need to let the elements sit for a while. This way the glue will penetrate deeper, the moisture will evaporate, and the adhesive substances contained in the glue will be concentrated. All this time, drafts and dust should be avoided on surfaces lubricated with the composition.
• Then the parts are connected. They should be pressed tightly against each other. In this case, part of the glue comes out in the form of a roller.
• Excess glue must be removed immediately with a damp cloth, spatula or scraper. If this is not done, the roller will harden and ruin appearance designs.
• The parts to be glued need to be kept under pressure for some time, using a vice or other equipment.

If the technology is followed, the connection is strong and reliable.

Glue is a mixture or substance, various multicomponent solutions, which are made on the basis of organic and inorganic substances. Using glue, different materials are connected: fabrics, wood, glass, metals, paper, leather, ceramics, rubber, plastics. Bonding occurs due to the formation of an adhesive bond between the surfaces being connected and the adhesive layer. The strength of adhesive joints can also be affected by cohesion to the adhesive surface. By type of gluing all existing adhesives are divided into non-drying, drying adhesives and bonds based on polymerizing compositions.

Wood glue is used to firmly fasten parts made of wood and other wood-based materials, such as cardboard, plywood or hardboard.

The main component of this type of glue is a protein substance that ensures strong adhesion. Depending on the raw materials used in the manufacturing process, wood glue can be fish glue, bone glue, hide glue, etc.

Hide glue

It is made from leather trimmings, waste from tanneries and flesh - the subcutaneous layer of fiber that is cut off when tanning animal skins.

Bone glue

This glue is boiled down from bone waste and ground bones. This is the most common type of wood glue.

Isinglass

It is made from fish processing waste: fish heads, entrails, scales, etc. are used. It is used, as a rule, when performing restoration and other complex work that requires High Quality and skill.

Casein glue

Brown-yellow powder made from dry low-fat cottage cheese and alkali. During the manufacturing process, this powder is poured into cold water and stirred constantly.

PVA glue

PVA wood glue is produced in tubes that can be used immediately. It dries quickly, is not washed off with water, but has a short shelf life. Despite this, it is currently in great demand among people.

Mucilage

This type of glue has not been widely used because it has weak adhesive properties. It is mainly made from starch and is used in the process of gluing wood surfaces and cloth.

Carpenter's glue "Moment"

Moment Joiner adhesive is intended mainly for carpentry work, which primarily includes gluing furniture parts. 20 minutes after its application, the parts are fixed, and after 24 hours the structure gains strength.

Glue "Moment Joiner" has excellent adhesive ability and is chemically neutral. The glued materials do not change their color and shape. The composition does not cause allergies and leaves no odor after complete drying. Apply glue to a cleaned and degreased surface at temperatures above +10°C.

Properties

Carpenter's glue is highly durable: under enormous loads, the destruction of the adjacent layer of wood in the structure occurs, rather than the adhesive layer of the joint.

The glue is usually produced in yellow-brown granules or hard slabs. It is believed that the more transparent and lighter the slabs or granules, the better quality glue.

Preparing glue before work

Before starting work, dry wood glue needs to be prepared. To do this, granules (when using a glue tile, you need to wrap it in cloth and break it into small pieces with a hammer) are poured in advance cold water so that the water covers the dry glue. The mixture is kept until it becomes a soft gelatinous mass. Basically, depending on the amount of glue, the procedure takes 4-12 hours.

After swelling, the glue is cooked for 15 minutes with constant stirring in a water bath at 60-80 degrees, until a uniform liquid mass without lumps is formed. You cannot heat the glue over normal heat - if the solution burns or boils, its adhesive ability is significantly reduced.

For cooking you should use special devices, which are called “Kleyanka”, having two metal vessels. Pour into a large vessel hot water, after which a smaller vessel with glue is inserted, and the glue is placed on low heat. Water is poured into the outer vessel so that when boiling it does not leak into the inner vessel with wood glue. It is better to choose glue boxes made of copper.

If necessary, it is easy to make such a device yourself from scrap materials. For example, you can take a large vessel as a vessel tin can, and place a small one inside glass jar, which should be installed on a stand or hung on a wire.

To obtain the required consistency of the glue solution, hot boiled water is either added during cooking or the cooking time is increased to evaporate excess moisture. For gluing tenon and end joints, it is better to make the glue a little thicker than for planar joints sheet materials(hardboard, plywood, etc.).

You should cook the amount of wood glue that is required to complete the current job, because, despite the available additives, over time the solution begins to lose its properties, and after three days it can rot and become moldy.

Application

Wood glue is used hot at temperatures up to 70 degrees until it thickens. As a rule, glue is capable of preserving desired temperature composition in room conditions without the need to reheat it for 2 hours.

Carpenter's glue is evenly applied to the gluing areas using a small brush.

To prevent the hot solution from being squeezed out too much, it is necessary to give the applied layer time to dry - approximately 2-5 minutes. After this, the surfaces are connected, the parts are slightly rubbed against each other, compressed with a clamp (or tightly tied with twine) and left for 4-6 hours until they are glued.

For strong and high-quality gluing with wood glue, the parts to be glued must be dry. Wood should not have a moisture content of more than 10 percent, veneer - no more than 5 percent.

Improving the quality of glue

By adding various additives to finished wood glue, you can make it more universal, suitable for joining materials other than wood.

Eg:

• The moisture resistance of the adhesive joint increases significantly if you add 10 g to 40 g of dry wood glue linseed oil or natural drying oil.
• To glue the skin, you need to add glycerin to the wood glue in a ratio of 1 tsp. half a liter of glue.
• If you add sifted wood glue to hot wood glue wood ash or dry chalk powder, you can get an excellent putty paste.

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Today the construction market exists wide choose excellent adhesive compositions providing high performance characteristics connections. Waterproof wood glue often cures stronger than the base surface. When choosing a composition, it is necessary to have information about the product’s ability to glue wood of different species and change its color.

Types of waterproof wood glue

1) Traditional wood glue is casein or bone glue, which until recently was widely used in woodworking. (Fig.1) It connects perfectly various surfaces, sets within 6-8 hours, has good adhesion and heat resistance, but is difficult to use (it needs to be heated, boiled and wait a long time for hardening).

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Casein wood glue used for gluing paper, cardboard, fabric and leather to wood. This is a very waterproof glue. To prepare the glue, you need to mix the powder (casein) with cold water until it reaches the consistency of sour cream; you need to mix the glue for about an hour. Then the glue is applied to both surfaces and allowed to dry for five minutes, after which they are connected. The glue sets in 6-8 hours, and dries completely in about 20. Using casein wood glue It should be remembered that it leaves stains on the wood, so it must be applied carefully.

Glue paste.

One of the types of wood glue. Making pasta is very simple. To do this, you need to mix hot wood glue with sifted ash or chalk. Glue paste is used for priming and puttying wood materials, as well as for gluing wooden parts, when connecting which gaps of more than 0.2 millimeters arise. Also, using a glue paste, wood is glued to metal, glass and stone.

And now we bring to your attention a video on how to properly glue wood. Enjoy watching!

Irina Zheleznyak, Staff correspondent for the online publication "AtmWood. Wood-Industrial Bulletin"