Plywood Grading Rules :Part 3 GRADES OF RUSSIAN PLYWOOD
More exact and detailed info ,please visit https://www.plywood.ru/plywood-standard-grade/ . You can download the PDF format for printing ,professtional grading rules for russia birch plywood . You can also visit http://www.plywoodinspection.com/category/grading-rules/ for more different grading rules from different countries and associations and industries .
GRADES OF RUSSIAN PLYWOOD
Quality description of Russian birch plywood according to the GOST 3916.1-96 standard
Birch plywood grade is defined by the face veneer quality. While some Russian plywood mills will offer proprietary or custom grades, the consensus grading standard is GOST 3916.1-1996, Russian National Standard for Birch Plywood. This document establishes unique characteristics for each species of wood veneer in face grades of B (I), BB (II), CP (III) and C (IV). This standard also provides standards for core grades and adhesives, and is a valuable resource for anyone buying or specifying Russian plywood.
What follows is a general description of the grade categories from the GOST 3916.1-96.
Solid-piece surface has light and uniform colour. A few small pin knots and some brown streaks are allowed. Veneer of this grade is intended for natural finishes. Patches are not allowed. The majority of Grade B veneers are the equivalent of the American “white birch” faces.
Solid-piece face has light and uniform colour. A few sound tight knots are permitted. Open knots and defects are eliminated and replaced with small oval or round veneer patches before gluing. The veneer selected for the patch is of the same colour as the basic face veneer. Generally there are very few patches per face and many users purchase this grade for natural finishes.
The “CP” veneers are downgraded from “BB” grade veneers, which allow for unlimited patches and sound knots, but does not allow for open defects. Thin splits are allowed. The oval or round patch may have a different colour than the face veneer. There are more patches per face allowed than in Grade BB.
Open defects such as open knots and veneer splits are allowed. Veneer lap and small core voids permitted. Sanding is not required. Recommended for the building of containers and dust panels; can be used for crating and in manufacturing, where construction and strength are more important than the appearance.
Patches in Baltic Birch
You’ll find several football, oval, or irregular shaped patches in either side of Baltic birch. Even the highest grade of Baltic furniture grade birchplywood allows for patches. While at first glance they might seem unsightly, they’re indeed correcting a worse problem that you wouldn’t like any better – such as knots or discoloration. Fortunately, patches are color matched, so they blend as best as they can to the surrounding areas.
Inner cores are solid birch single piece veneers.
Sourced from https://www.plywood.ru/plywood-standard-grade/ .