Part 1 ‑ Substrate (Bare Birch Plywood) Defects (inherited from base veneer)
Same core wood defects as standard birch plywood before UV coatingСвеза.
| No. | Defect Description |
|---|---|
| 1 | Pin knots |
| 2 | Sound / intergrown knots (light‑dark) |
| 3 | Partially intergrown knots |
| 4 | Black knots, loose knots, knot‑holes (no bark inclusions) |
| 5 | Close shakes |
| 6 | Open shakes / open veneer splits |
| 7 | Timber‑structure flaws: diagonal grain, swirly grain, burls, bud traces |
| 8 | Inner inbark (light / dark) |
| 9 | Open inbarks |
| 10 | Sound discoloration (false heartwood) |
| 11 | Sound discoloration: streaks & streak traces |
| 12 | Congested streaks |
| 13 | Mineral streaks, sap stains, storage discoloration, blue‑stain |
| 14 | Biological damage (wormholes) |
| 15 | Discoloration with partial wood damage |
| 16 | Wooden‑insert knot patching |
| 17 | Double patch repairs |
| 18 | Shake / crack filling quality |
| 19 | Overlap ridges (telegraphing overlaps) |
| 20 | Veneer overlap |
| 21 | Manufacturing beam marks / lines |
| 22 | Glue stains (substrate) |
| 23 | Mechanical defects: pin‑holes, saw‑cuts |
| 24 | Scratches, grooves, pimples, ridges (substrate before coating) |
| 25 | Warping / bow / twist |
| 26 | Adhesive threads |
| 27 | Blisters, delamination, bark patches |
| 28 | Sander skips / uneven sanding |
| 29 | Face‑veneer over‑sanding |
| 30 | Metal inclusions (staples etc.) |
| 31 | Edge defects: sanding/cutting fringe, veneer shortage |
| 32 | Coarse peeling |
| 33 | Waviness, rough‑saw cut, ripple |
| 34 | Rough‑surface (Rm roughness per GOST 7016) |
| 35 | Pockets (no bark inclusions) |
| 36 | Pasted veneer chips |
Part 2 ‑ UV‑Coating‑Specific Finishing Defects
These defects occur during UV varnish application / UV‑curing processСвеза.
| No. | UV‑Coating Defect | Description |
|---|---|---|
| U1 | Coating delamination / peeling | UV film lifts, flakes or detaches from birch veneer substrate; adhesion failure (must not occur per STO spec)Свеза. |
| U2 | Pinholes in coating | Tiny perforations through UV layer revealing bare wood underneath. |
| U3 | Coating bubbles | Air bubbles trapped inside cured UV film. |
| U4 | Orange‑peel texture | Wavy uneven surface texture of UV finish, not matching agreed gloss / smoothness. |
| U5 | Brush / roll marks | Visible application roller streaks, directional flow marks across panel face. |
| U6 | Fish‑eyes | Circular crater‑like depressions in UV coating caused by surface contamination. |
| U7 | Dust / specks / foreign inclusions | Solid dirt / particles embedded inside or sitting on top of cured UV film. |
| U8 | Scratches & mar‑marks | Fine or deep surface scratches on finished UV face; scratch breaking through to wood substrate = major defect. |
| U9 | Gloss deviation | Gloss value outside agreed tolerance. Standard: 5‑10 GU ±2; >10 GU ±5 (60° gloss‑meter measurement)Свеза. |
| U10 | Colour shade variation / gradient spots | Visible panel‑to‑panel or within‑sheet tint difference, cloudy gradient areas on clear/tinted UV finishСвеза. |
| U11 | Coating miss / bare spots | Missing UV varnish; substrate wood fully exposed in localised zones. |
| U12 | Over‑cure / under‑cure symptoms | Tacky surface (under‑cure); brittleness / fine network cracking (over‑cure). |
| U13 | Crazing / coating cracking | Fine hair‑line cracks in UV varnish film, may follow wood grain or cross‑grain. |
| U14 | Edge coating chip / chipping | Chipping / flaking of UV finish along panel perimeter edges. |
| U15 | Coating bleed‑over on un‑coated edges | UV varnish smudge / overflow onto cut raw‑wood edges when only one‑side UV is ordered. |
| U16 | Indentations / dents on coated surface | Dents coming from substrate OR press‑marks after UV curing, visible through transparent UV film. |
Part 3 ‑ Dimensional & General QC Items
表格
| Item | Requirement Notes |
|---|---|
| Sheet dimension (length × width) | Check actual vs nominal size; squareness tolerance (diagonal difference)Свеза. |
| Thickness tolerance | Measure multiple points across sheet. |
| Moisture content | Birch plywood substrate moisture (typical 6‑10 %). |
| Warping (bow / twist) | Max allowed deflection per meter diagonal as per base‑plywood grade. |
| Edge quality | Saw cut quality, splintering, veneer gaps, delamination at edges / corners. |
| Formaldehyde emission | E1 / E0 / CARB‑P2 / ULEF as per contract requirement. |
| Glue‑line integrity | No delamination, no voids in plywood core. |
Part 4 ‑ Practical QC Check‑List Table (for on‑site inspection)
Major = reject condition; Minor = allow within agreed limit / quantity.
| Inspection Item | Major Defect (Reject) | Minor Defect (Accept within limit) | Observation / Measured Value | M / Mi | Pass / Fail |
|---|---|---|---|---|---|
| Substrate wood‑defects | Open loose knots, large knot‑holes, extensive delamination, heavy bark inclusions beyond grade limit | Pin‑knots, small sound intergrown knots, allowed streaks & discoloration within grade specs | |||
| UV coating adhesion | Peeling / flaking coating | Very local tiny lifting (zero tolerance for high‑grade UVX)Свеза | |||
| UV film continuity | Bare wood spots, large pin‑hole clusters | Sparse micro‑pinholes within agreed max count per m² | |||
| Surface texture & finish | Bubbles, fish‑eyes, heavy orange‑peel, heavy roller marks | Minor orange‑peel, isolated small specks within limit | |||
| Scratches | Deep scratches penetrating through UV down to wood substrate | Fine superficial scratches limited in length & quantity | |||
| Gloss & colour | Gloss outside contract tolerance; obvious sheet‑to‑sheet shade mismatch | Minor gloss deviation within tolerance; faint natural wood‑grain colour variation | |||
| Coating cracking / crazing | Any network / widespread coating cracks | Isolated micro‑hairline cracks (if contract allows) | |||
| Edges & corners | Large chipping of UV coating, corner delamination | Minor edge‑coating chip within size limit | |||
| Dimensions, thickness, squareness | Exceeds dimensional tolerance | Minor tolerance within specification | |||
| Warp / twist | Warping exceeds grade‑specified limit | Warping within permitted value |
Note: UV‑prefinished birch plywood still inherits base‑plywood‑grade restrictions (UV‑clear finish is transparent and does NOT hide substrate veneer defects)Свеза. Final acceptance always follows customer purchase agreement & referenced STO‑standard.
UV‑Sheen (Satin / Semi‑Gloss UV Finish) Birch Plywood
Sheen: subjective visual light‑reflection appearance; measured as Gloss Units (GU) @ 60° gloss meter (ISO‑2813 / ASTM‑D523)Alibaba.co…. UV‑Sheen mostly refers to satin / low‑medium semi‑gloss UV prefinished birch plywood (typical 8‑35 GU), widely used for furniture, cabinet, interior panels. Reference standards: STO 00255177‑001‑2013 (birch substrate); STO 52654419‑015‑2024 (SVEZA‑UV coating spec). Inspection lighting: 800‑1200 lux diffused light, grazing‑angle viewing for sheen uniformity check.
1. UV‑Sheen Standard Gloss Tolerance (60° GU)
| UV‑Finish Grade | Typical 60° GU | Factory Tolerance (STO‑spec) |
|---|---|---|
| UV‑Matte / Low‑Sheen | 5‑10 GU | ± 2 GU |
| UV‑Satin / Medium‑Sheen | 12‑35 GU | ± 5 GU |
| UV‑Semi‑Gloss | 35‑60 GU | ± 5 GU |
| UV‑High‑Gloss | 70‑90 GU | ± 5 GU |
Human eye can visually detect sheen difference ≥ 3‑5 GU on large flat panels. Measurement rule: minimum 3 reading points per sheet (top‑left, centre, bottom‑right); cross‑check against approved master‑panel reference sample.
2. Sheen‑Related Defect List (UV‑Sheen Birch Plywood)
表格
| Code | Defect Name | Description | Root Cause | Major / Minor |
|---|---|---|---|---|
| S‑01 | Sheen mottling / blotchy sheen | Patchy non‑uniform reflectivity within one single sheet; bright & dull irregular zones visible under grazing light | Uneven primer sanding; variable wet‑film UV‑thickness; roller‑pressure fluctuation; local substrate porosity | Major |
| S‑02 | Sheet‑to‑sheet sheen variation | Consistent gloss offset between different panels in same batch; one sheet reads 12 GU, next reads 22 GU out of tolerance | Coating‑varnish batch change; UV‑lamp power drift; roller speed shift; inconsistent curing energy | Major |
| S‑03 | Sheen gradient / flow‑line sheen | Directional streaks of rising/falling sheen following roller machine direction | Roller‑application marks, uneven varnish levelling before UV curing | Major‑if obvious; Minor‑if faint only at extreme angle |
| S‑04 | Local low‑sheen dull spots | Isolated dull dim spots, lower GU reading, no physical scratch | Surface dust/contamination before coating; micro‑oil/silicone contamination (fish‑eye precursors) | Major if > 5 mm or multiple spots |
| S‑05 | Local high‑sheen bright spots | Small glossy hot‑spots standing out against surrounding satin‑sheen finish | Local over‑cure; thin primer revealing substrate; repair touch‑up marks | Major if visible under normal viewing distance |
| S‑06 | Sheen change over patched areas | Patches / wood inserts show different sheen level vs surrounding veneer | Patch substrate absorbs primer differently; sanding difference on repair zones | Minor if subtle; Major if sharp contrast |
| S‑07 | Orange‑peel texture (sheen distortion) | Wavy micro‑surface texture altering perceived sheen, even if gloss‑meter reading stays within GU tolerance | Varnish viscosity, insufficient levelling time before UV‑cure | Major for furniture‑grade UV‑sheen panels |
| S‑08 | Buff / polish marks (rub marks) | Circular / linear rub‑tracks with altered sheen from post‑cure handling | Cleaning / buffing operations after UV curing | Minor‑isolated faint; Major‑multiple obvious tracks |
Important note: Natural birch veneer grain can create minor visual sheen variation (grain‑valley vs grain‑peak). This is natural wood feature, NOT coating defect, compare vs master‑sample to distinguish defect vs natural grain effect.
3. Full QC Checklist for UV‑Sheen Prefinished Birch Plywood
Part A: Substrate Birch‑Veneer Defects (inherit STO 00255177‑001‑2013, previously‑listed 36 wood‑defect items)
- Base plywood grades available for UV‑sheen: B/B, B/BB, BB/BB, B/CP, BB/CP (single‑side or double‑side UV‑sheen coated)
- All knots, shakes, inbark, discoloration, patching, waviness, warping must comply with substrate‑grade limits; transparent UV‑sheen does NOT hide substrate‑veneer defects.
Part B: UV‑Coating General Defects (combined with sheen‑check)
| Inspection Item | Major Defect (Reject) | Minor Defect (Accept within agreed limit) | Measured Value | M / Mi | P/F |
|---|---|---|---|---|---|
| Sheen / Gloss Uniformity | 1. Gloss‑meter reading outside contract GU‑tolerance2. Visible mottling / blotchy‑sheen / sheet‑to‑sheet mismatch vs master‑panel | Faint natural‑grain‑related light‑reflection variation only (matches master‑sample) | Avg GU ____ ; Min‑Max GU ____ | ||
| UV‑Coating Adhesion (Cross‑hatch ISO 2409) | Peeling / flaking coating (classification > 1) | Zero tolerance for furniture grade; no minor allow | Adhesion class ____ | ||
| Coating continuity | Bare‑spots, large pin‑hole clusters | Sparse micro‑pinholes within agreed max‑count / m² | Pinhole count ____ pcs/m² | ||
| Surface texture & finish | Bubbles, fish‑eyes, heavy orange‑peel, heavy roller‑marks | Minor orange‑peel within master‑panel reference | |||
| Scratches & rub‑marks | Deep scratches breaking through UV‑film down to wood | Superficial fine scratches, limited length & quantity | Scratch count ____ | ||
| Crazing / coating cracks | Network / widespread coating cracking | Isolated micro‑hairline cracks (only if contract explicitly permits) | |||
| Edge & corner finish | Large UV‑coating chipping, corner‑delamination | Minor edge‑chip within size‑limit; UV‑bleed‑over for single‑side coated panels | Max chip size ____ mm | ||
| Dimension / thickness / squareness | Exceeds drawing‑tolerance | Deviation within specification | Diagonal diff ____ mm | ||
| Warp / Twist | Warping exceeds substrate‑grade limit | Warping within permitted deflection | Warp ____ mm/m | ||
| Colour / tint variation | Obvious panel‑to‑panel colour mismatch | Natural wood‑tone grain variation matching master‑sample |
Part C: Performance Test Items for UV‑Sheen Birch Plywood
- Gloss / Sheen measurement: 60° gloss‑meter ISO‑2813, min 3 points per sheet, batch‑sampling
- Adhesion cross‑hatch test ISO‑2409 (requirement class 0‑1)
- Pencil hardness test (typical furniture‑grade ≥ 2 H)
- Moisture‑content of birch substrate: 6‑10 %
- Formaldehyde emission (E1 / CARB‑P2 / ULEF as per purchase order)
- Glue‑line integrity (boil test for WBP exterior plywood)
4. Practical Inspection Tips for UV‑Sheen Panels
- Always inspect at grazing low‑angle light (not direct perpendicular overhead light). Most sheen‑mottling defects only show under grazing view.
- Keep approved physical master‑reference panel on‑site; visual judgement must compare to master‑sample, do not rely only on gloss‑meter numbers (meter‑GU can pass while visual mottling still appears due to micro‑texture / orange‑peel).
- Distinguish: natural‑grain‑caused light‑reflection difference (OK) vs coating‑process‑caused blotchy‑sheen (defect‑reject).
