Important Warning: This is a historical archive text, not a current standard, technical specification or manufacturing manual. Markings, dimensions, tolerances, classifications, adhesives and other technical values ​​must be checked according to valid standards, manufacturer’s documentation and specific project requirements.

This text is not a description of a separate product in the current offer of Savo Kusić. The current offer is focused on windows, doors and related solutions.

Types of veneer and plywood

There are two types of veneer: cut and sawn. Sliced ​​veneer is used for the production of plywood for doors, carpentry boards, frames, constructions, furniture, etc. Veneer is used for covering wood of weaker species, boards made of wood fibers, etc.  Plywood consists of three or more thin layers of peeled wood glued together so that the fibers of one are perpendicular to the fibers of the others.

Plywood is made from birch, alder, ash, elm, oak, beech, linden, aspen, pine, spruce, cedar and fir. The outer layers of plywood are called cladding and the inner layers are called middle. When the number of layers is even, then the two middle layers should have parallel fiber direction. With respect to water resistance, plywood is made of the following brands: FSF plywood with increased water resistance, which is glued with phenol-formaldehyde type adhesives; FK and FBA - plywood with medium water resistance, glued with carbamide or albumin casein glues; FB plywood with limited water resistance, glued with protein glues. Depending on the type of processing of surface sheets, plywood can be sanded on one or both sides and unsanded. The main dimensions of plywood are given in table.

Plywood dimensions

Table 3: Main dimensions of plywood, mm Length (or width) Allowed deviations Width (or length) Allowed deviations 1830 ± 5 1220 ± 4,0 1525 ± 5 1525 ± 5,0 1525 ± 5 1220 ± 4,0 1525 ± 5 725 ± 3,5 1220 ± 5 725 ± 3,5

The length of one sheet of plywood is measured in the direction of the fibers of the outer sheets. Plywood is made with a thickness of 1,5; 2,0; 2,5; 3; 4; 5; 6; 8; 9; 10 and 12 mm. The minimum thickness of birch and alder plywood is determined to be 1,5 mm, and from other types of wood - 2,5 m. Deviations of unsanded plywood by thickness in mm are allowed: For plywood thickness in mm 

  • 1,5; 2,0 i 2,5 - ± 0,2
  • 3,0 - ± 0,3
  • 4,5 i 6,0 - ± 0,4
  • 8,0; 9,0 i 10,0 - ± 0,4 do 0,5
  • 12,0 - ± 0,6

When sanding plywood, the reduction of its thickness on one side (taking into account the permitted deviations) must not be greater than 0,2 mm, on both sides 0,4 mm. According to the quality, veneer for plywood is made in the following types: A, A1, AB, AB1, B, BB, C. Data for the selection of sheets are given in the table. 4.

Selection of sheets and quality of gluing

Table 4: Selection of sheets for various types of plywood
Salt sheets Type of plywood
A A1 AB AB1 B BB C
List type
Face A A AB AB B BB C
Reverse AB B B BB BB C C

Symmetrically distributed thin layers of wood (according to the thickness of the plywood) should be of the same type of wood and of equal thickness.

Plywood must be firmly glued, without bubbles, it must not delaminate when bending. The ultimate shear strength per layer of glue is given in table. 5.  

Table 5: Ultimate shear strength per adhesive layer kg/cm3 (minimum) Plywood name Plywood with increased water resistance Medium water resistance plywood Plywood with limited resistance With carbamide glue With albumin casein glues After 1h in boiling water After being kept in water within 24h In the dry state After 1h in boiling water In the dry state Birches...
Alder, beech, linden, ash, elm, oak, fir, pine, spruce and cedar...
Aspen... 12 12 12 5 12 10 10 10
6 4
3 10
6

Delivery of plywood according to dimensions, classes, brands, types of wood, direction of wood fibers in sheets and method of processing is carried out according to the customer’s specifications. Sanded plywood is obtained by sanding wood on special machines for sanding plywood and is used as a covering material for wood products.

Types of cut veneer

Sanded veneer is divided into radial, semi-radial, tangential and tangential - front, which are obtained from tree stumps (tab. 6).

Table 6: Characteristics of various types of plywood Type of beadwork Characteristics by years by core rays Radial The lines have the appearance of straight, parallel lines Core rays in the form of transverse bands are located at least on 3/4 plate surface Semi-radial The same Core rays in the form of oblique or longitudinal stripes are located at least on 1/2 plate surface Tangential The pods that form the growth cones have the appearance of oblique bands or lines The medullary rays have the appearance of longitudinal or oblique bands or lines Tangential - frontal For years they have the appearance of closed curved lines or bands Core rays have the appearance of curved lines or bands

According to the quality of the wood, plywood is divided into three classes: I, II and III. 

Dimensions, humidity and finish quality of the veneer

Veneer is made from oak, beech, walnut, chub, maple, ash, elm, chestnut, sycamore, Amur velvet, pear, apple, poplar, cherry, acacia, birch, elm and hornbeam.

The length of radial, semi-radial and tangential veneers goes from 1,0 m and more; tangentially - frontally - from 0,3 and higher with an increase of 0,1 m.

The thickness of the veneer is for each species - 0,8; 1,0; 1,2; 1,5 mm.

Table 7: Width of plywood sheets of different types, mm Veneer type I class Class II III class Radial, semi-radial and tangential 130 100 80 Tangential - frontal 200 150 100

Deviations from the prescribed thickness dimensions (in mm) are allowed:

  • Za furnir debljine 0,8 mm -  ± 0,05 
  • Za furnir debljine 1,0 mm -  ± 0,08
  • Za furnir devljine 1,2 - 1,5 mm - ± 0,1

The humidity of the veneer is 10 ± 2%.

In terms of wood quality, the veneer must meet the requirements of the existing standard. Veneer sheets must have a clean flat surface, without roughness, scratches, cracks and metal stains.