Such a seemingly simple task as choosing plywood turns out to be not the easiest. When purchasing material for a project, you need to make sure whether the plywood meets the required operational characteristics and aesthetic criteria. And here, as a rule, the most difficult part begins.

Due to the presence of a large assortment of products and a rather confusing standardization system, even the sellers themselves often cannot clearly explain how some varieties and types of plywood differ from others. In our article we will consider in as much detail as possible key points related to the choice of plywood and its main characteristics.

What is plywood and why is it so valued?

Plywood is a sheet material that has a layered glued structure of three or more sheets of wood. Each layer of veneer is applied so that its fibers are perpendicular to the previous sheet. Thanks to this, plywood has high strength, rigidity and dimensional stability, which distinguishes it from ordinary wood.

For the outer layers of plywood, veneer of deciduous trees (birch, alder, maple, beech, linden, etc.), and less often of coniferous trees, is used. Its thickness does not exceed 3.5 mm. For the inner layers, it is allowed to use veneer of both hardwood and softwood, in the latter case we are talking about the so-called. combined plywood.

How thick is plywood?

According to GOST 3916.1-96 Thick plywood sheets available in the market 3 mm, 4 mm, 6,5 mm, 9 mm, 12 mm, 15 mm, 18 mm, 21 mm, 24 mm, 27 mm and 30 mm. But if necessary, manufacturers can create material of any thickness agreed with the customer. The material can contain from 3 to 21 layers of veneer. The thickness of the sheet determines which saw to cut the plywood with. Typically a circular saw is used for these purposes.

What types of plywood are there?

Plywood is classified according to many parameters:

• operational purpose (construction, general use, furniture, decorative, etc.);
• degree of water resistance of the adhesive joint;
• type of surface treatment (polished/unpolished);
• thickness and number of layers;
• sheet dimensions;
• emission class, etc.

However, the main criterion that determines the characteristics of a plywood sheet is its grade indicator.

Intelligible information about plywood varieties

There are five grades of plywood. The belonging of a material to one or another grade is determined by its visual and aesthetic characteristics, i.e. quality of external veneer and the number of permissible defects.

According to GOST 3916.1-96 plywood grades are designated " E», « I», « II», « III», « IV».

Along with this marking, they are actively used old system classification established GOST 3916.1-89. In accordance with it, plywood is also divided into five grades, but is designated differently: “ A», « AB», « IN», « BB», « WITH" Since both indexings are still used, for convenience we will give the old markings in parentheses.

Grade E (A). Plywood elite class, which does not have visible flaws or processing defects on its surface. According to established standards, only minor defects in the form of an uneven texture pattern are allowed in such material. The presence of knots, holes, cracks and wormholes, shoots and other wood defects is not allowed.

Grade I (AB). This type of plywood may have defects in the outer veneer layers, but within strictly established limits. The length of warping and cracks should not exceed 20 cm, and the number of such defects cannot be more than 2 pieces. per 1 m of sheet width. In first grade plywood, such defects as lack of veneer, healthy intergrown light and dark knots with a diameter of no more than 15 mm in an amount of no more than 5 pieces are allowed. per 1 m 2. Open cracks, dark growth, unhealthy discoloration, dents and other defects are excluded.

Grade II (B). The plywood sheet may contain cracks up to 20 cm long, patch inserts, and mechanical defects such as scratches or dents. There may be slight leakage of glue and overlap of the top layer veneer. One sheet of second grade plywood is allowed to have up to 6 of the following defects: dark and light knots, holes, wormholes with a diameter of no more than 6 mm.

Grade III (BB). A plywood sheet of the third grade may contain both healthy and partially fused or fallen knots, wormholes with a diameter of up to 6 mm (up to 10 per 1 m2). GOST allows for patch inserts, gaps in veneer joints, moderate glue seepage, edge defects, overlaps and veneer shortages.

Grade IV (C). The lowest quality type of material. In the fourth grade, all plywood defects are allowed in unlimited quantities.

In the marking, the grade of plywood sheet is indicated through a fraction, for example, I/II. This means that veneer of the first grade was used for the front side, and second grade for the back.

Degree of water resistance of the adhesive joint

In addition to the type of veneer, plywood differs from each other in the characteristics of the adhesive connection. Based on this indicator, the following grades of material are distinguished.

FSF– material of increased water resistance for external and internal use. The adhesive joint of plywood is created using phenol-formaldehyde resins. Thanks to them, the material is characterized by increased water resistance, mechanical strength, dimensional stability, and wear resistance. The flip side of the advantages of FSF brand plywood is the high percentage of toxic phenolic compounds. In addition, the resin used for gluing veneer is flammable, and the combustion products of the resins themselves pose a real threat to human health.

FC– waterproof plywood for interior use based on urea glue. This type of material differs from the FSF brand in lower water resistance, but at the same time it is completely environmentally friendly and odorless. FC grade material is chosen for interior decoration residential and technical premises, furniture creation, etc. The environmental safety of plywood and low flammability make it optimal for burning.

FB– plywood with increased water resistance, which uses bakelite varnish. In addition to resistance to critical humidity levels, this material demonstrates unsurpassed mechanical strength, wear resistance and is adapted to large temperature changes. FB plywood retains all its operational advantages even with prolonged contact with water.

What to look for when choosing plywood?

The brand, grade and thickness of plywood are the main criteria that are used when choosing a material.

Guests may differ, but it is better to always check the quality of the material yourself. To decide which plywood to choose, first inspect the edges of the material. In high-quality plywood, the inner layers of veneer should be straight, of the same thickness, without overlaps or gaps. The heterogeneity of the internal layers not only impairs the performance of the material, but can also appear on outside plywood sheet, create unnecessary problems when cutting it and at the finishing stage.

Before purchasing plywood, it would be a good idea to visually assess the straightness of the sheet. Even a small bend can turn into serious warping due to the release of internal stresses after the sheet is cut.

Plywood is a multilayer material in the form of square plates, which is made by gluing together several layers of wood veneer. It is widely used in construction, mechanical engineering, furniture production and other fields. Often ordinary consumers ask the following question: “FSF plywood - what is it?” This product, its features, and advantages will be discussed in this article.

Features of FSF plywood

So, FSF plywood - what does it mean? F - plywood, SF - resin phenol-formaldehyde glue. This wood material is made from birch, coniferous or beech veneer. It has properties of increased moisture resistance. Plywood consists of three or more layers of veneer glued together with formaldehyde glue. It is characterized by dark red or dark brown adhesive layers between the plates, which are visible at the ends of the canvases.

FSF plywood, specifications which allow its operation in any climatic conditions is natural material with a beautiful aesthetic appearance. It is used for construction and outdoor finishing works. It is not recommended to use the material indoors, as it contains toxic substances.

Moisture-resistant plywood can be made from softwood. According to production technology, coniferous veneer must be present in the outer layers. Internal plates can be made of hardwood. This type of plywood is used in construction. It is resistant to rot and fungi. FSF birch plywood is characterized by excellent quality, strength, wear resistance and high cost. All layers in this product are made of birch wood, which is 15-20% stronger and heavier than coniferous wood.

Moisture-resistant FSF plywood:

• when stretched it is 40 MPa;
• when bending - 60 MPa;
• when chipping along the adhesive layer - 1.5 MPa.

Scope of application

FSF plywood, whose technical characteristics are quite high, justifies its use in the field of electrical engineering, in the aviation industry, in construction, in the car and automotive industries. This material is used in the construction of frame structures, fences, formwork structures, and roofing work. FSF 18 mm plywood is widely used for manufacturing garden furniture, outdoor advertising billboards, packaging and containers.

Advantages of plywood

FSF plywood (what kind of material this is is written above in the article) has many advantages.

1. Increased moisture resistance. Moisture or condensation formed does not affect its technical characteristics. At the same time, it does not swell, does not come apart and retains its strength properties.
2. Resistant to mechanical damage. Due to their structure, plywood sheets withstand the effects of bending and tearing. This wood material is strong and durable.
3. Simplicity and speed of installation. The material is easy to process and comfortable, which facilitates simple and quick installation. It can be secured using self-tapping screws, screws, and nails. Combines well with other synthetic or natural materials.
4. Versatility. Reliability and moisture resistance allow it to be used in various fields of application.
5. Ease of processing. FSF plywood, although it has increased strength, is easily processed with tools. It lends itself well to grinding, drilling and cutting.

It is these indicators that ensure the popularity of plywood and its use in industry and construction.

Disadvantages of FSF plywood

• Toxicity. When using carcinogenic components that affect human health. Use of this material indoors is not recommended.
• Flammability. The material is highly flammable.

FS plywood grades

FS plywood is distinguished into five grades: E (elite), 1, 2, 3, 4. The material is divided into categories based on the outer surface layers:

• E - perfect quality outer sheets;
• I (B) - product without visible defects;
• II (BB) - absence of knots on the plywood sheet, the presence of black dots is acceptable;
• III - (CP) it is possible to seal defects with veneer inserts;
• IV grade (C) - the presence of knots is acceptable;
• SS - the most low grade, veneer joints and other flaws are visible on the sides of the canvas.

According to the degree of surface treatment, FSF can be:

• NS - unpolished;
• Ш or Ш 1 - with one-sided grinding;
• Ш or Ш 2 - with double-sided grinding.

A letter symbol is added to the marking of the material and grade, which indicates the degree of processing of the sheet. In addition, the formaldehyde emission class must be indicated. This type of plywood is produced with a thickness of 4-40 mm. The dimensions of the FSF plywood sheet are: 1525x1525, 1220x2440, 1250x2500 mm.

How to distinguish FSF plywood from other types

If you don’t know how FSF plywood differs from other types, what kind of material it is, what its characteristics are, ask a sales consultant or determine it yourself. external signs. At the ends of the panels, veins of dark glue are visible between the layers of veneer. FC plywood, unlike FSF, has light yellow adhesive gaps.

Price

If you need moisture-resistant FSF plywood, the price of sheets same sizes and thickness may vary. First decide on the type of material. The cost depends on the type of product and its manufacturer. The number of defects present on the surface of the outer layers of the material determines one or another of its grades. And, naturally, the higher the grade, the more expensive the product. Since plywood has two outer sides, the grade is determined by double numbering, for example 2/4. In addition, each manufacturer of FSF plywood sets its own prices for its products. Therefore, the cost says little about the quality of the product.

The concept of “plywood” is a collective term that combines sheets glued together from three or more layers of wood veneer. Wood fibers are usually perpendicular, which allows plywood to hold its shape and resist dynamic loads.

Currently, plywood class is very popular FC And FSF. However, disputes between finishers about the quality of products and their environmental safety continue. Let's try to understand this issue.

Decoding abbreviations

First, let's look at the definitions. In both cases, we are talking about material made from certain types of wood. Usually it looks like this:

birch- all layers of plywood sheet are made from this type of wood.

coniferous trees- pine is used as a raw material.

combined options- the outer layers are made of birch, the inner layers are made of pine.

What's the difference? All plywood on the market differs from each other in its adhesive composition. In deciphering the abbreviation, the first letter indicates the name of the material. In our case, "F" stands for plywood.

Further symbols identify the glue that was used to make the sheet. In particular:

TO- urea-formaldehyde.

SF- phenol-formaldehyde resin.

The difference in adhesive composition largely determines the technical properties of plywood. For example, the series material FC often used in the production of cabinet and upholstered furniture.

FSF- more suitable for interior partitions and billboards. The scope of application is determined by the fact that the resin phenol-formaldehyde makes the sheets more resistant to humid environments.

Key differences between the submissions

Application of different adhesive compositions suggests for each type of plywood its own technical features and scope. The table compares the two materials.

Comparative review two types of plywood
Criterion
Fire safety*
Environmental Safety	No phenol	Phenol is present at a concentration of 8 mg/100 g**
Moisture resistance	After getting wet and then drying, it delaminates	Does not delaminate after being in a humid environment
Scope of application	In rooms with low humidity	Indoors and outdoors (under canopies, in outbuildings)
Gluing	Urea-formaldehyde composition	Phenol-formaldehyde composition
Flexural strength MPa
On a leaf cut	Single-color, light (layers of veneer and glue are the same color)	Multi-colored, light veneer layers are combined with dark adhesive

*If you need non-flammable plywood - choose FSF-TV, impregnated with a special composition. It is used in passenger carriage construction.

**Security class assigned E-1- permission for use in residential premises. However, in some rooms, especially in the nursery, it is undesirable to use.

In terms of presentation, both types of plywood are identical. There are several categories here: the higher the class, the fewer external defects.

Regardless of these features, FSF often used for rough work, FC gets the finishing function.

Look to the root! Visual differences

Visually, both types of plywood are very similar. Similar types of wood veneer are used here, laminated coating and sheet sanding are provided. However, there are external differences, and they are due to the difference in the adhesive composition.

Plywood FC does not contain phenol, so it looks lighter. The interlayers and veneer sheets have identical color scheme, so they look like a homogeneous material. FSF has layers of a dark red hue. Knowing these features, it is easy to distinguish between types of plywood, even without special skills and knowledge in the field of construction.

Which is safer for your health?

If environmental safety plays a decisive role, it is better to choose plywood FC. Here, silicate glue is used for gluing sheets, which is neutral artificial material without chemically active additives.

In case of FSF the question is controversial. According to requirements GOST applied to this type of material, the phenol content in the composition does not exceed the permissible values. In addition, this substance is actively and widely used in medicine, agriculture and even the food industry.

However, in terms of toxicity, the component belongs to the second class chemical hazard. This means that there is only a thin line between acceptable and exceeded concentrations. Therefore, if you want to maintain a healthy atmosphere in your home, it is better not to risk it.

A worthy alternative

Fun fact:

It was from this that kamikaze planes were constructed, hence the idiomatic expression “plywood over Paris.”

When choosing plywood for finishing work, do not forget about such a category of material as FB. Deciduous or softwood veneer is also used here. However, before gluing, the sheets are impregnated with bakelite varnish; the glue is made on the basis of water- or alcohol-soluble resins.

Thanks to these features, the material does not have the disadvantages of plywood. FC And FSF, while embodying the best qualities.

It looks like this:

plywood has high moisture resistance and does not lose its original qualities even in sea water;

the material does not ignite and does not support the spread of open fire - the sheet will char but will not flare up;

there are no toxic components in the composition, so plywood of this series can be used in children's institutions;

wide range of operating temperatures combined with resistance to almost any aggressive environment;

life time at least 10 years without loss of initial characteristics;

In terms of strength, such plywood is twice as strong as wood.

It should be noted that the characteristics of plywood FB confirmed by time: it was this material that was used to make kamikaze planes.

With a lot of undeniable advantages, the material has very significant drawback. For the price of this plywood at least 2 times superior to other analogues.

Plywood is divided into grades in accordance with the requirements of GOST No. 3916.1-96. The grade of plywood is determined according to the amount of defects on the surface of the plywood. This refers to traces of knots, which are the most vulnerable places in any wood.

There are 5 types of plywood in total:

• E (Elite) grade of plywood: no visible defects or blemishes. Minor deviations in the structure of the wood are allowed, of a random nature, except for dark eyes. Not allowed: partially fused, unfused, falling knots, holes from them, wormholes, healthy fused knots, minor brown veins, etc. This plywood can be coated with varnish. Grade E plywood is used to make laminated plywood.
• 1st grade: 1st grade plywood has virtually no defects, partially fused, unfused, falling out knots, holes from them, wormholes with a diameter of no more than 6 mm are allowed. In the amount of 3 pieces. per 1 m², no more than 5 healthy fused knots per 1 m² with a diameter of up to 15 mm are also allowed. and slight brown streaks. This plywood can be varnished. Grade I plywood is used for the production of laminated plywood.
• 2nd grade: in grade 2 plywood, partially fused, unfused, falling out knots, holes from them, wormholes with a diameter of no more than 6 mm are allowed, in the amount of 6 pieces. per 1 m², no more than 10 healthy fused knots per 1 m² with a diameter of up to 25 mm are also allowed, repairing the surface of the sheet is allowed. Knots and open defects are sealed with veneer inserts. This plywood is covered with various finishing materials and paints.
• 3rd grade: in grade 3 plywood, partially fused, unfused, falling out knots, holes from them, wormholes with a diameter of no more than 6 mm are allowed, in the amount of 10 pcs. per 1 m² of sheet surface, healthy fused knots are also allowed without limiting the number. It is used for the manufacture of structures hidden from external view, for the manufacture of containers and packaging.
• 4th grade: in grade 4 plywood, any manufacturing defects are allowed. Partially fused, unfused, falling knots, holes from them, wormholes are allowed in unlimited quantities with a diameter of no more than 40 mm, only good gluing is guaranteed. Used for the manufacture of durable containers and packaging.

Examples of plywood surface different varieties:

Sample of plywood grade E Sample of plywood grade 1 Sample of plywood grade 2 Sample of plywood grade 3 Sample of plywood grade 4

Conclusion: The most high grade plywood - E (elite) - it is extremely rare and is relatively expensive. The market mainly offers plywood grades from 1 to 4. Grade 1 is the highest, grade 4 is the lowest. The higher the grade of plywood, the better quality its surface.

Indication of grade in plywood markings

The grade is written after the plywood size in Roman or Arabic numerals. The sides of the sheet may be of the same type, or they may be different.

Example notation:

• "FC plywood 1525×1525×9 mm, 4/4"- stands for: FK plywood - FK brand plywood, i.e. moisture resistant; 1525×1525×9 mm - sheet size: length 1525mm, width 1525mm, thickness 9mm; 4/4 - grade 4/4, i.e. both sides of the sheet of the same type (in in this case- 4th grade)
• "FK plywood 1525×1525×9 mm, 2/4, w.2"— Difference compared to the first option: 2/4 - grade 2/4, i.e. one side is 2nd grade 2, the other is 4th grade; line 2 - i.e. polished on both sides.

The main “running” varieties: 1/2, 2/2, 2/3, 2/4, 3/4, 4/4.
The 4/4 grade is not sanded, while all other grades are all sanded on both sides.