What does B/BB mean in Baltic birch plywood?

Two letters, face then back: a B face and a BB back. B is the best face in normal Baltic trade — sound, tight and suitable for a clear finish. BB permits sound knots and oval patches that match the surrounding grain. The letters describe appearance only and say nothing about the core, which is solid birch in every grade.

Is Baltic birch grade B the same as ANSI grade B?

No, and assuming so under-reads the panel by two grades. B is the top face grade in Baltic trade practice, while ANSI/HPVA HP-1 grade B is the third of six, after AA and A. The letter is the same and the position on the scale is not.

What is the American standard for hardwood plywood grades?

ANSI/HPVA HP-1, published by the Decorative Hardwoods Association. Its face grades run AA, A, B, C, D and E from best to worst, and Table 3.1 covers birch alongside ash, beech, maple and poplar. The table carries a footnote reading "American or European", so it applies to Baltic birch on its own terms.

What is the difference between GOST 3916.1-96 and GOST 10.55-71?

They are two scales for the same material. GOST 3916.1-96 uses E, I, II, III and IV, where E stands for Elite and is the best. GOST 10.55-71 uses the letters B, BB, CP and C that appear on trade documents. They do not map one to one: for knots the letter grades are sometimes more permissive, while for processing defects such as overlaps and glue lines they are consistently stricter.

Does grade E mean the best or the worst plywood?

It depends entirely on the standard. In GOST 3916.1-96 grade E is Elite, the highest grade, essentially free of defects. In ANSI/HPVA HP-1 grade E is the last of six and the most permissive face the standard defines. The same letter marks the best panel on one system and the worst on the other, which is why a grade letter should never travel without the standard it belongs to.

Does the grade affect the strength of the plywood?

No. Face grade describes the appearance of the outer veneer — knots, patches, colour and repairs. The core construction is the same across grades: cross-banded birch veneer with no voids. A C-grade panel is as stiff as a B-grade panel of the same thickness and carries the same load.

Which grade should I order for cabinets?

B/BB where a face will be seen under a clear finish, BB/BB where both sides show but a patch is acceptable, and BB/CP for carcase work where one side is hidden. Paying for a B face on a part that ends up inside a cabinet is the most common way to overspend on birch.

Is a knot hole allowed in B grade Baltic birch?

Yes, within limits, and this surprises people. Under GOST a loose or missing knot up to 6 mm is permitted on a B face at up to three per square metre — B is the best trade grade, not a flawless one. It is the Elite grade of GOST 3916.1-96 that excludes them. Under ANSI/HPVA HP-1 an unfilled hole is not allowed in any grade at all; it may only appear patched.

Are patches allowed in B grade plywood?

Not under GOST. Wooden inserts are excluded from E, B and grade I, and first appear at BB — which is exactly what the second letter of B/BB is telling you. Under HP-1 repairs are permitted from grade B onwards, capped at 3.2 mm, so the same letter again means a different panel.

How do I stop a grade misunderstanding on an order?

Name the standard next to the letter — "B/BB to GOST 10.55-71" rather than "grade B" — and state the finish the panel is going under. If the specification came from an architect working to ANSI, ask which standard the letter refers to before quoting, because the same letter on the two systems is a different panel.

Plywood Grades: Baltic Letters vs the American Standard

The same letter means a different panel on each system. Grade E is the best plywood in one standard and the worst in the other. Here is what each side actually permits, with the numbers.

01 — The collision

Three letters that mean opposite things

A buyer sends a specification written to the American standard. A mill quotes back in Baltic trade letters. Both documents say “B”, both parties believe they agree, and they are describing panels two grades apart.

This is not a translation problem that careful reading solves. The two systems were built independently and reused the same alphabet in different orders. The only defence is to name the standard beside the letter, every time.

Baltic / GOST: GOST 3916.1-96 grade E is Elite — the highest grade in the standard, essentially free of defects.
ANSI/HPVA HP-1: HP-1 grade E is the last of six, the most permissive face grade the standard defines.

The same letter marks the best panel on one system and the worst on the other.

Baltic / GOST: The best face grade in normal Baltic birch trade. A B face is what you specify for a clear finish.
ANSI/HPVA HP-1: Third of six, after AA and A. Permits sound knots to 9.5 mm and blending repairs.

A US buyer reading "B/BB" as HP-1 grade B is under-reading the face by two grades.

Baltic / GOST: The bottom of the standard range. Open defects are allowed; used unsanded, for packaging and construction.
ANSI/HPVA HP-1: Fourth of six, and still a working face — knots to 12.7 mm, repairs permitted.

Baltic C is markedly rougher than American C, and the two should never be quoted against each other.

02 — Is my defect allowed?

Look it up by the defect, not by the standard

Standards are written standard-first. The question never arrives that way — you are holding a panel with a split in it, not a copy of GOST 10.55-71. Pick what is on the panel and read both answers at once.

What is on the panel?

Sound knots

Also called: tight, live or intergrown knots

Baltic grades — GOST

Sound knots permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Up to 10 mm	no	allowed	allowed	allowed	allowed	allowed	allowed	allowed	allowed
Up to 25 mm, max 25 per m²	no	allowed	no	allowed	no	allowed	allowed	allowed	allowed
With cracks 0.5–1.0 mm wide	no	no	no	no	allowed	allowed	allowed	allowed	allowed
With cracks up to 1.5 mm	no	no	no	no	no	no	allowed	allowed	allowed
With cracks over 1.5 mm	no	no	no	no	no	no	no	no	allowed

American grades — ANSI/HPVA HP-1

Sound knots permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Sound + repaired, average number	None	None	4 per 3 m²	3 per m²	4 per m²	No limit
Maximum size, sound	—	—	9.5 mm	12.7 mm	25.4 mm	38 mm

Pin knots

Also called: pinholes, small dark specks

Baltic grades — GOST

Pin knots permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Up to 3 per m²	no	allowed	allowed	allowed	allowed	allowed	allowed	allowed	allowed
Up to 8 per m²	no	allowed	no	allowed	allowed	allowed	allowed	allowed	allowed

American grades — ANSI/HPVA HP-1

Pin knots permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Inconspicuous burls & pin knots	2 per m²	4 per m²	6 per m²	No limit	No limit	No limit
Conspicuous pin knots	None	4 per 3 m²	3 per m²	No limit	No limit	No limit
— maximum size, total	—	6.4 mm	6.4 mm	—	—	—

Loose knots & knot holes

Also called: fallen-out knots, open holes, wormholes

Never under HP-1. Unfilled — never, in any HP-1 grade. They may only appear patched.

Baltic grades — GOST

Loose knots & knot holes permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
To 6 mm, max 3 per m²	no	allowed	allowed	allowed	allowed	allowed	allowed	allowed	allowed
To 6 mm, up to 6 per m²	no	no	no	no	allowed	allowed	allowed	allowed	allowed
To 6 mm, up to 10 per m²	no	no	no	no	no	allowed	allowed	allowed	allowed
To 40 mm, up to 10 per m²	no	no	no	no	no	no	no	allowed	allowed
To 40 mm, unlimited	no	no	no	no	no	no	no	no	allowed

American grades — ANSI/HPVA HP-1

Loose knots & knot holes permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Repaired knots, average number	None	None	4 per 3 m²	3 per m²	4 per m²	No limit
— maximum size, repaired	—	—	3.2 mm	12.7 mm	19 mm	25.4 mm

Cracks & splits

Also called: checks, open seams, end splits

Never under HP-1. Open splits — never, in any HP-1 grade. Only blended repaired hairline splits are permitted.

Baltic grades — GOST

Cracks & splits permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Closed, at the edge, to 200 mm	no	allowed	allowed	allowed	allowed	allowed	allowed	allowed	allowed
Open, to 2 mm wide, to 250 mm	no	no	no	allowed	allowed	allowed	allowed	allowed	allowed
Open, to 2 mm wide, 200–300 mm, 2/m²	no	no	no	no	no	allowed	allowed	allowed	allowed
Open, over 2 mm wide	no	no	no	no	no	no	no	allowed	allowed

American grades — ANSI/HPVA HP-1

Cracks & splits permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Blended repaired hairline splits	Two, 0.8 × 76 mm, panel ends only	Two, 1.6 × 152 mm	Four, 3.2 × 203 mm	Four, 4.8 × 203 mm	Six, 6.4 × 254 mm	Yes

Patches & inserts

Also called: plugs, footballs, boat patches, putty

Baltic grades — GOST

Patches & inserts permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Up to 8 per m²	no	no	no	allowed	allowed	allowed	allowed	allowed	allowed
No limit	no	no	no	no	no	allowed	allowed	allowed	allowed
Double insert	no	no	no	no	allowed	allowed	allowed	allowed	allowed
Loose putty with an open joint	no	no	no	no	no	allowed	allowed	allowed	allowed

American grades — ANSI/HPVA HP-1

Patches & inserts permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Repairs	Very small, blending	Small, blending	Blending	Yes	Yes	Yes
Repaired knots, max size	—	—	3.2 mm	12.7 mm	19 mm	25.4 mm

Discolouration & streaks

Also called: stain, mineral streak, false heartwood

Baltic grades — GOST

Discolouration & streaks permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Light streak	no	no	allowed	allowed	allowed	allowed	allowed	allowed	allowed
Dark streak	no	no	no	allowed	allowed	allowed	allowed	allowed	allowed
Dark streak from 25 mm, 10 per m²	no	no	no	no	no	allowed	allowed	allowed	allowed
False heartwood, from 250 × 10 mm	no	no	no	no	no	allowed	allowed	allowed	allowed
Sound discolouration	no	no	allowed	allowed	allowed	allowed	allowed	allowed	allowed
Unsound discolouration	no	no	no	no	no	no	no	allowed	allowed

American grades — ANSI/HPVA HP-1

Discolouration & streaks permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Mineral streaks	No; Maple, slight	Slight	Slight	Yes	Yes	Yes

Worm tracks & vine marks

Also called: insect tracks, bark inclusions

Baltic grades — GOST

Worm tracks & vine marks permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Wormholes to 6 mm — see loose knots	no	allowed	allowed	allowed	allowed	allowed	allowed	allowed	allowed

American grades — ANSI/HPVA HP-1

Worm tracks & vine marks permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Worm tracks	Slight	Slight	Slight; Ash, yes	Yes	Yes	Yes
Vine marks	Slight	Slight	Slight	Yes	Yes	Yes
Cross bars	Slight	Slight	Yes	Yes	Yes	Yes

Bark pockets

Also called: bark inclusions in the face

Never under HP-1. Open bark pockets — never, in any HP-1 grade.

Baltic grades — GOST

Bark pockets permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Bark, blisters, delamination	no	no	no	no	no	no	no	no	no

American grades — ANSI/HPVA HP-1

Bark pockets permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Bark pockets	No	No	Few, 3.2 × 25.4 mm	Few, 6.4 × 50.8 mm	6.4 × 50.8 mm	Yes

Rough grain & sanding marks

Also called: ruptured grain, oversanding, ripple

Baltic grades — GOST

Rough grain & sanding marks permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Oversanding	no	no	no	no	no	no	no	allowed	allowed
Waviness, pile, ripple (sanded)	no	no	no	no	no	no	allowed	allowed	allowed
Surface roughness over 100 Rm	no	no	no	no	no	no	no	allowed	allowed
Scratches	no	no	no	no	allowed	allowed	allowed	allowed	allowed
Dents, imprints, ridges	no	no	no	no	allowed	allowed	allowed	allowed	allowed

American grades — ANSI/HPVA HP-1

Rough grain & sanding marks permitted by ANSI/HPVA HP-1 face grade
Limit	AA	A	B	C	D	E
Rough cut / ruptured grain	No	No	Slight	Two 203 mm areas	5% of panel	10% of panel

Overlaps in the outer plies

Also called: lapped veneer, double thickness

Baltic grades — GOST

Overlaps in the outer plies permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Length to 100 mm	no	no	no	no	allowed	no	allowed	no	allowed
Length to 200 mm	no	no	no	no	no	no	allowed	no	allowed
Over 200 mm	no	no	no	no	no	no	no	no	allowed

American grades — ANSI/HPVA HP-1

HP-1 does not cover this. A pressing fault, not an appearance characteristic. HP-1 has no clause for it.

Glue lines & open joints

Also called: glue bleed, gaps between veneer strips

Never under HP-1. Open joints — never, in any HP-1 grade.

Baltic grades — GOST

Glue lines & open joints permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Glue line showing through	no	no	no	no	allowed	no	allowed	no	allowed
Glue percolation	no	allowed	no	allowed	allowed	allowed	allowed	allowed	allowed
Gap in joints	no	no	no	no	allowed	no	allowed	no	allowed
Missing veneer, edge to 2 mm	no	no	allowed	no	allowed	no	allowed	no	allowed
Missing veneer, edge to 4 mm	no	no	no	no	allowed	no	allowed	no	allowed

American grades — ANSI/HPVA HP-1

HP-1 does not cover this. HP-1 sets no limit on glue lines, but open joints are banned outright in every grade.

Metallic inclusions

Also called: staples, wire, tramp metal

Baltic grades — GOST

Metallic inclusions permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Metallic inclusions	no	no	no	no	no	no	allowed	no	allowed

American grades — ANSI/HPVA HP-1

HP-1 does not cover this. Not addressed. HP-1 grades what the face looks like, not what is inside it.

Warp & flatness

Also called: bow, cup, twist

Baltic grades — GOST

Warp & flatness permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Warp, panels to 6.5 mm	allowed	allowed	allowed	allowed	allowed	allowed	allowed	allowed	allowed
Over 15 mm per metre of diagonal	no	no	no	no	no	no	no	no	no

American grades — ANSI/HPVA HP-1

HP-1 does not cover this. No numeric limit. HP-1 defines a balanced panel as one “free from warp that affects serviceability for its intended use” — a judgement, not a figure.

Thickness out of spec

Also called: panel too thin, too thick, uneven

The Baltic allowance widens with the panel and the American one is flat, so they cross at 12 mm: below that the mill is tighter, above it PS 1 is. Unsanded is looser on both, because the calibrating sander is what sets the final figure.

Permitted thickness deviation, Baltic mill and PS 1-22
Nominal	Baltic, sanded	Baltic, unsanded	PS 1, sanded	PS 1, unsanded
4 mm	±0.1 mm3.90–4.10	±0.24 mm	±0.4 mm	±0.8 mm
6 mm	±0.2 mm5.80–6.20	±0.36 mm	±0.4 mm	±0.8 mm
9 mm	±0.3 mm8.70–9.30	±0.54 mm	±0.4 mm	±0.8 mm
12 mm	±0.4 mm11.60–12.40	±0.72 mm	±0.4 mm	±0.8 mm
15 mm	±0.5 mm14.50–15.50	±0.90 mm	±0.4 mm	±0.8 mm
18 mm	±0.5 mm17.50–18.50	±1.08 mm	±0.4 mm	±0.8 mm
21 mm	±0.6 mm20.40–21.60	±1.26 mm	±0.4 mm	±0.8 mm
24 mm	±0.7 mm23.30–24.70	±1.44 mm	±0.4 mm	±0.8 mm
27 mm	±0.8 mm26.20–27.80	±1.62 mm	±0.4 mm	±0.8 mm
30 mm	±0.9 mm29.10–30.90	±1.80 mm	±0.4 mm	±0.8 mm

Baltic figures are Syktyvkar Plywood Mill's published tolerance to DIN 68705-3, with the mill's own note that unsanded C grade runs to ±6% of nominal — one mill's specification, not a universal Baltic rule, so confirm it against whoever pressed your panel. American figures are the footnotes to Table 10 of NIST PS 1-22. ANSI/HPVA HP-1 has no thickness table at all: clause 2.2.5 leaves it to the manufacturer.

Rot & doze

Also called: decay, punk, soft spots

Never under HP-1. Doze — never, in any HP-1 grade.

Baltic grades — GOST

Rot & doze permitted by GOST grade
Severity	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Rot	no	no	no	no	no	no	no	no	no

American grades — ANSI/HPVA HP-1

HP-1 does not cover this. Doze is banned outright in every HP-1 face grade.

The two standards are shown side by side, not equated. GOST answers whether a defect is permitted; HP-1 answers how large or how many. A panel can satisfy one and fail the other, which is why a grade letter should always travel with the standard it belongs to.

03 — The short version

One question, both standards, side by side

Nine things that actually change a buying decision, asked of each standard in turn. Ordered by how much they matter, which is why open defects and core construction come before cosmetics.

Open defects — unfilled knot holes, splits, joints

GOST: Permitted from grade C / IV. Knot holes and wormholes to 6 mm appear at B, to 40 mm at C, unlimited at IV.
ANSI/HPVA HP-1: Not allowed in any face grade. The standard names unfilled wormholes, open splits, open joints, open bark pockets and doze and forbids all of them outright.

The most permissive American face is still closed. The cheapest Baltic face is not.

Core construction

GOST: Baltic birch is cross-banded birch veneer throughout, with no voids, in every grade.
ANSI/HPVA HP-1: Veneer, particleboard and MDF cores are all covered. The face grade letter says nothing about what is underneath.

The reason most shops buy Baltic birch is invisible in the grade letter on either system.

How the grade is written

GOST: Face and back from one scale, separated by a slash: B/BB, BB/CP, C/C.
ANSI/HPVA HP-1: Face letter plus back number: A-2, B-3. Inner plies carry their own grades, J to M.

Different alphabets on each side of the mark. There is no arithmetic that lines them up.

Warp

GOST: A number: deflection over 15 mm per metre of diagonal is not permitted in any grade.
ANSI/HPVA HP-1: No numeric limit. A balanced panel is defined as one “free from warp that affects serviceability for its intended use”.

One standard gives you a figure to measure against, the other gives you a judgement to argue about.

Falling-out knots and knot holes

GOST: To 6 mm: 3 per m² from B, 6 per m² from II, 10 per m² from CP. To 40 mm from C. Unlimited at IV.
ANSI/HPVA HP-1: Only as repaired knots: 4 per 3 m² at B, 3 per m² at C, 4 per m² at D. Unfilled, never.

GOST counts the hole. HP-1 counts the patch over it.

Patches and wooden inserts

GOST: Up to 8 per m² from BB, without limit from CP. Double inserts from II.
ANSI/HPVA HP-1: Repaired knots: 4 per 3 m² at B, 4 per m² at D. Maximum repair size 3.2 mm at B, 12.7 mm at C, 25.4 mm at E.

Both count patches; only HP-1 also caps how big each one may be.

Cracks and splits

GOST: Closed edge cracks to 200 mm from B. Open cracks to 2 mm wide from BB, over 2 mm from C.
ANSI/HPVA HP-1: Open splits never. Blended repaired hairline splits only, 1.6 × 152 mm at A rising to 6.4 × 254 mm at D.

An open split is an ordinary feature of a lower Baltic grade and a rejection under HP-1.

Sound knots, maximum size

GOST: 10 mm from B. 25 mm with up to 25 per m² from B, though not until III on the numeric scale.
ANSI/HPVA HP-1: 9.5 mm at B, 12.7 mm at C, 25.4 mm at D, 38 mm at E.

The closest the two systems come to agreeing: roughly 10 mm at the top of the working range on both.

Face veneer thickness

GOST: Set by the panel construction — an 18 mm panel is 13 plies, so roughly 1.4 mm a layer.
ANSI/HPVA HP-1: Explicitly left open: “will vary according to the design and intended use as specified by the manufacturer”. No minimum.

Nothing in an American grade letter promises there is enough face left to sand.

Every GOST entry above is the first grade that permits the defect, read off the source matrix rather than estimated. Every HP-1 entry is quoted or measured from ANSI/HPVA HP-1-2024. The two are still not being equated — one question is put to both standards and both answers are printed.

04 — The Baltic letters

B, BB, CP, C — and the two scales behind them

A Baltic birch grade is written as two letters, face then back. B/BB is a B face over a BB back. The face letter is the one you pay for.

B: Best face in normal trade. Sound and tight, small discolouration permitted, a few pin knots. Clear finish, lacquer, toning.
BB: Sound knots and open defects are patched with oval inserts matched to grain and colour. Paint, veneer overlay, semi-transparent finish.
CP: Patches and discolouration without limit, filler permitted. Opaque finish, film-facing, painted work.
C: Open defects of structure and processing are allowed, usually supplied unsanded. Construction and packaging, where the face does not show.

Behind those letters sit two standards, not one. GOST 10.55-71 is where the trade letters come from. GOST 3916.1-96 is the current standard and grades E, I, II, III, IV — where E is Elite and the best.

They are not interchangeable, and the table further down shows exactly where they part company: on knots the letter grades are sometimes the more permissive of the two, while on processing defects — overlaps, glue lines, gaps at joints — they are consistently stricter.

One more trap. Mills also use letters of their own. At least one major Baltic mill markets an E grade that sits just below B — permitting discolouration over 30% of the face against B’s 15% — which is neither the Elite of GOST 3916.1-96 nor the E of the American standard. A third meaning for the same letter. Ask what the mill means by it.

05 — The American standard

What ANSI/HPVA HP-1 permits on a birch face

These are the limits from Table 3.1 of ANSI/HPVA HP-1-2024, the table covering ash, beech, birch, maple and poplar. Its footnote reads “American or European” — so the standard covers Baltic birch by its own terms, not by anyone’s interpretation.

Worth noticing how quickly the scale opens up. Between grade B and grade D the permitted sound knot goes from 9.5 mm to 25.4 mm and the count from four per three square metres to four per square metre — roughly nine times the knot area.

ANSI/HPVA HP-1-2024 face grade limits for birch
Characteristic	AA	A	B	C	D	E
Inconspicuous burls & pin knots, average number	2 per m²	4 per m²	6 per m²	No limit	No limit	No limit
Conspicuous burls, maximum size	6.4 mm (¼")	9.5 mm (⅜")	12.7 mm (½")	No limit	No limit	No limit
Conspicuous pin knots, average number	None	4 per 3 m²	3 per m²	No limit	No limit	No limit
Sound and repaired knots, combined average	None	None	4 per 3 m²	3 per m²	4 per m²	No limit
— maximum size, sound	—	—	9.5 mm (⅜")	12.7 mm (½")	25.4 mm (1")	38 mm (1½")
— maximum size, repaired	—	—	3.2 mm (⅛")	12.7 mm (½")	19 mm (¾")	25.4 mm (1")
Rough cut / ruptured grain	No	No	Slight	Two 203 mm areas	5% of panel	10% of panel
Repairs	Very small, blending	Small, blending	Blending	Yes	Yes	Yes
Mineral streaks	No	Slight	Slight	Yes	Yes	Yes
Bark pockets	No	No	3.2 × 25.4 mm, few	6.4 × 50.8 mm, few	6.4 × 50.8 mm	Yes

Unfilled wormholes, open splits, open joints, open bark pockets, or doze are not allowed in any of the above grades. Source: ANSI/HPVA HP-1-2024, Table 3.1a and 3.1b, published by the Decorative Hardwoods Association. Metric and inch-pound figures are both from the standard; where we have converted for readability the original value is shown alongside.

06 — The two GOST scales

Defect by defect, GOST 10.55-71 against GOST 3916.1-96

Columns run best to worst, left to right, with the two scales interleaved so you can read across from a trade letter to the numeric grade beside it. + means the defect is permitted, − that it is not.

This comparison is ANTPLY’s own work. It has since been copied onto other sites without attribution, which we take as a compliment and note here so the origin is on the record.

Permitted defects by grade under GOST 10.55-71 and GOST 3916.1-96
Defect	E3916.1-96	B10.55-71	I3916.1-96	BB10.55-71	II3916.1-96	CP10.55-71	III3916.1-96	C10.55-71	IV3916.1-96
Knots	E	B	I	BB	II	CP	III	C	IV
Pin knots, up to 3 per m²	−	+	+	+	+	+	+	+	+
Pin knots, up to 8 per m²	−	+	−	+	+	+	+	+	+
Sound intergrown, light and dark, up to 10 mm	−	+	+	+	+	+	+	+	+
Sound intergrown, up to 25 mm, max 25 per m²	−	+	−	+	−	+	+	+	+
Sound intergrown, with 0.5–1.0 mm cracks	−	−	−	−	+	+	+	+	+
Sound intergrown, with cracks up to 1.5 mm	−	−	−	−	−	−	+	+	+
Sound intergrown, with cracks over 1.5 mm	−	−	−	−	−	−	−	−	+
Partly intergrown, loose or missing; wormholes to 6 mm, max 3 per m²	−	+	+	+	+	+	+	+	+
Same, up to 6 per m²	−	−	−	−	+	+	+	+	+
Same, up to 10 per m²	−	−	−	−	−	+	+	+	+
Up to 40 mm, up to 10 per m²	−	−	−	−	−	−	−	+	+
Up to 40 mm, unlimited number	−	−	−	−	−	−	−	−	+
Overlaps in the outer plies	E	B	I	BB	II	CP	III	C	IV
Length up to 100 mm	−	−	−	−	+	−	+	−	+
Length up to 200 mm	−	−	−	−	−	−	+	−	+
Length over 200 mm	−	−	−	−	−	−	−	−	+
Missing veneer, edge defects from sanding and trimming	E	B	I	BB	II	CP	III	C	IV
Width up to 2 mm	−	−	+	−	+	−	+	−	+
Width up to 4 mm	−	−	−	−	+	−	+	−	+
Processing	E	B	I	BB	II	CP	III	C	IV
Glue line showing through	−	−	−	−	+	−	+	−	+
Grain dent	−	−	−	−	+	−	+	−	+
Metallic inclusions	−	−	−	−	−	−	+	−	+
Gap in joints	−	−	−	−	+	−	+	−	+
Glue percolation	−	+	−	+	+	+	+	+	+
Scratches	−	−	−	−	+	+	+	+	+
Dents, imprints, ridges	−	−	−	−	+	+	+	+	+
Oversanding	−	−	−	−	−	−	−	+	+
Waviness, pile, ripple (sanded panels)	−	−	−	−	−	−	+	+	+
Surface roughness over 100 Rm	−	−	−	−	−	−	−	+	+
Cracks	E	B	I	BB	II	CP	III	C	IV
Closed, edge, up to 200 mm	−	+	+	+	+	+	+	+	+
Open, up to 2 mm wide, up to 250 mm	−	−	−	+	+	+	+	+	+
Open, up to 2 mm wide, 200–300 mm, 2 per m²	−	−	−	−	−	+	+	+	+
Open, over 2 mm wide	−	−	−	−	−	−	−	+	+
Wood structure	E	B	I	BB	II	CP	III	C	IV
Light streak	−	−	+	+	+	+	+	+	+
Dark streak	−	−	−	+	+	+	+	+	+
Dark streak from 25 mm, 10 per m²	−	−	−	−	−	+	+	+	+
False heartwood, from 250 mm long, 10 mm wide	−	−	−	−	−	+	+	+	+
Slight incidental deviation, except dark eyelets	+	+	+	+	+	+	+	+	+
Sound discolouration	−	−	+	+	+	+	+	+	+
Unsound discolouration	−	−	−	−	−	−	−	+	+
Rot	−	−	−	−	−	−	−	−	−
Chips	−	+	+	+	+	+	+	+	+
Wooden inserts (patches)	E	B	I	BB	II	CP	III	C	IV
Up to 8 per m²	−	−	−	+	+	+	+	+	+
No limit	−	−	−	−	−	+	+	+	+
Double insert	−	−	−	−	+	+	+	+	+
Loose puttying of knots with an open joint	−	−	−	−	−	+	+	+	+
Panel condition	E	B	I	BB	II	CP	III	C	IV
Warp, panels up to 6.5 mm	+	+	+	+	+	+	+	+	+
Warp over 15 mm per metre of diagonal	−	−	−	−	−	−	−	−	−
Delamination, blisters, bark	−	−	−	−	−	−	−	−	−

Read row four for the point of the whole exercise: a 25 mm sound knot is permitted on trade grade B but not on grade I, and on BB but not on II. The letters are looser there. Then read the overlaps and glue-line rows, where II and III permit what BB and CP forbid outright. Neither scale is simply stricter than the other.

07 — In practice

How to write a grade so it cannot be misread

Name the standard beside the letter: Write “B/BB to GOST 10.55-71”, not “grade B”. Four extra words remove the entire ambiguity this page describes.
Say what the finish will be: A face grade exists to serve a finish. “Clear lacquer, face must take stain evenly” tells a mill more than any letter, and lets us tell you when you are paying for more face than the job needs.
Ask which standard an architect meant: A specification calling for grade A or grade B without a standard is almost always written to ANSI. Confirm before quoting; the difference is two grades and a lot of money.
Remember the back is half the panel: B/BB and BB/BB differ only on the hidden side. On carcase parts that face a wall, the back letter is where the saving is.
Grade is appearance, never strength: Every grade shares the same void-free birch core. A C-grade panel carries the same load as a B-grade panel of the same thickness — see the thickness guide for what actually drives stiffness.
Get a sample before a first order: Grade descriptions are limits, not photographs. Two mills can both ship legitimate BB and look different. One sheet settles it before a truckload does not.

For what the grades look like on our own stock, see grades explained · thickness guide · sizes & tolerances

08 — Questions

Grades, asked plainly

What does B/BB mean in Baltic birch plywood?: Two letters, face then back: a B face and a BB back. B is the best face in normal Baltic trade — sound, tight and suitable for a clear finish. BB permits sound knots and oval patches that match the surrounding grain. The letters describe appearance only and say nothing about the core, which is solid birch in every grade.
Is Baltic birch grade B the same as ANSI grade B?: No, and assuming so under-reads the panel by two grades. B is the top face grade in Baltic trade practice, while ANSI/HPVA HP-1 grade B is the third of six, after AA and A. The letter is the same and the position on the scale is not.
What is the American standard for hardwood plywood grades?: ANSI/HPVA HP-1, published by the Decorative Hardwoods Association. Its face grades run AA, A, B, C, D and E from best to worst, and Table 3.1 covers birch alongside ash, beech, maple and poplar. The table carries a footnote reading "American or European", so it applies to Baltic birch on its own terms.
What is the difference between GOST 3916.1-96 and GOST 10.55-71?: They are two scales for the same material. GOST 3916.1-96 uses E, I, II, III and IV, where E stands for Elite and is the best. GOST 10.55-71 uses the letters B, BB, CP and C that appear on trade documents. They do not map one to one: for knots the letter grades are sometimes more permissive, while for processing defects such as overlaps and glue lines they are consistently stricter.
Does grade E mean the best or the worst plywood?: It depends entirely on the standard. In GOST 3916.1-96 grade E is Elite, the highest grade, essentially free of defects. In ANSI/HPVA HP-1 grade E is the last of six and the most permissive face the standard defines. The same letter marks the best panel on one system and the worst on the other, which is why a grade letter should never travel without the standard it belongs to.
Does the grade affect the strength of the plywood?: No. Face grade describes the appearance of the outer veneer — knots, patches, colour and repairs. The core construction is the same across grades: cross-banded birch veneer with no voids. A C-grade panel is as stiff as a B-grade panel of the same thickness and carries the same load.
Which grade should I order for cabinets?: B/BB where a face will be seen under a clear finish, BB/BB where both sides show but a patch is acceptable, and BB/CP for carcase work where one side is hidden. Paying for a B face on a part that ends up inside a cabinet is the most common way to overspend on birch.
Is a knot hole allowed in B grade Baltic birch?: Yes, within limits, and this surprises people. Under GOST a loose or missing knot up to 6 mm is permitted on a B face at up to three per square metre — B is the best trade grade, not a flawless one. It is the Elite grade of GOST 3916.1-96 that excludes them. Under ANSI/HPVA HP-1 an unfilled hole is not allowed in any grade at all; it may only appear patched.
Are patches allowed in B grade plywood?: Not under GOST. Wooden inserts are excluded from E, B and grade I, and first appear at BB — which is exactly what the second letter of B/BB is telling you. Under HP-1 repairs are permitted from grade B onwards, capped at 3.2 mm, so the same letter again means a different panel.
How do I stop a grade misunderstanding on an order?: Name the standard next to the letter — "B/BB to GOST 10.55-71" rather than "grade B" — and state the finish the panel is going under. If the specification came from an architect working to ANSI, ask which standard the letter refers to before quoting, because the same letter on the two systems is a different panel.

09 — Enquiries

Send us the specification

If a drawing calls for a grade and you are not certain which standard it was written to, send it over. We will tell you what it maps to in Baltic letters and, more usefully, whether it is the grade the job actually needs — including when a lower one would do the same work for less.

Plywood Grades: Baltic Letters vs the American Standard

Three letters that mean opposite things

Look it up by the defect, not by the standard

Sound knots

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Pin knots

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Loose knots & knot holes

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Cracks & splits

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Patches & inserts

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Discolouration & streaks

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Worm tracks & vine marks

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Bark pockets

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Rough grain & sanding marks

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Overlaps in the outer plies

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Glue lines & open joints

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Metallic inclusions

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Warp & flatness

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

Thickness out of spec

Rot & doze

Baltic grades — GOST

American grades — ANSI/HPVA HP-1

One question, both standards, side by side

Open defects — unfilled knot holes, splits, joints

Core construction

How the grade is written

Warp

Falling-out knots and knot holes

Patches and wooden inserts

Cracks and splits

Sound knots, maximum size

Face veneer thickness

B, BB, CP, C — and the two scales behind them

What ANSI/HPVA HP-1 permits on a birch face

Defect by defect, GOST 10.55-71 against GOST 3916.1-96

How to write a grade so it cannot be misread

Grades, asked plainly

Send us the specification

Request current availability & price