북유럽 침엽수종 제재목 품질 등급 규정

북유럽 침엽수종 제재목 품질 등급 규정 (Nordic softwood grading rules / Blue book)

우리나라에서 가장 많이 사용하는 목재는 단연 소나무류 포함한 침엽수종의 제재목이다. 그리하여 목재에서도 가장 많이 수입되는 제품도 또한 이러한 목재들이며, 여기에는 주로 Pine (소나무류), Spruce(가문비나무류), Fir(전나무류)가 있었으나, 최근에는 중국에서 삼목(Cedar류)나 비슷한 종류이긴 하지만 일본에서 들어오는 Hinoki(편백류)나무들이 수입되어 들어오고 있기도 하다.

이러한 침엽수종들은 그 특성상 주로 온대지방이나 한대지방 등 상대적으로 기온이 낮거나, 고도가 높은 곳에서 자라는 나무들로, 따라서 주요 수입국들도 이러한 기후조건을 가지고 있는 캐나다나 미국 그리고 북유럽(스웨덴, 핀란드, 에스토니아, 라트비아 등) 그리고 러시아 지역이다.

이러한 침엽수종의 목재들은 우리나라 뿐만 아니라 세계적으로도 많은 거래가 이루어 지고 있기 때문에, 일정한 품질 유지를 위한 품질등급이 필요하며, 아직 세계적으로 통일된 품질규격이 있지는 않지만, 각기 국가별 혹은 지역별로 품질등급을 가지고 있는 경우가 많다. 대표적인 수입국인 미국, 캐나다는 거의 비슷한 품질등급을 사용하고 있으며, 러시아는 GOST라는 독자적인 품질등급이 있고, 스칸디나비아 지역에서 사용되는 등급은 비록 스웨덴이나 핀란드 뿐 아니라 발틱3국을 포함한 여러 유럽국가에서 사용되고 있다.

여기에서는 북유럽에서 사용되고 있는 제제목 품질등급을 소개한다. (www.nordictimber.org)

 

• The main grades are A, B, C and D.
• Grade A, the highest quality, is divided into subgrades A1 to A4.
• Grades B, C and D are not divided

 

GRADE A (old classification I to IV or choice U/S unsorted)	Knots	Shakes	Wane	Other imperfections
GRADE A1 (old classification I)	Small sound or dead knots < 7 mm are not considered. Tolerance of 1 intergrown knot per side with a diameter up to 8 mm. Knots clusters, through or dead, are not permitted.	Not admitted	Excluded	Warp must not exceed 2% of the piece's width. Slope of grain must not exceed 1 cm per 15 cm of length.
GRADE A2 (old classification II)	Tolerance of 2 sound knots per side and 1 per edge. The size of these knots must not exceed 25 mm per 75 mm of thickness and 225 mm of width. 1 dead knot is admitted with a size of 70% of the permitted sound knots. All other types of knots (clusters, barkringed, unsound) are excluded.	Not admitted	Excluded	Warp must not exceed 2% of the piece's width. Slope of grain must not exceed 1 cm per 15 cm of length. Gum pocket of 20 mm is tolerated on the poorest meter
GRADE A3 (old classification III)	3 sound knots per side and one per edge. The size of these knots must not exceed 35 mm per 75 mm of thickness and 225 mm of width. 1 barkringed knot is admitted with a size of 50% of the permitted sound knots.	Tolerated on 5 % of the length of a piece with 25 mm of thickness	Excluded	Warp must not exceed 2% of the piece's width. Slope of grain must not exceed 1 cm per 12 cm of length. Gum pocket of 40 mm is tolerated on the poorest meter
GRADE A4 (old classification IV)	4 sound knots per side and 2 per edge. The size of these knots must not exceed 45 mm per 75 mm of thickness and 225 mm of width. 2 barkringed knots are admitted on the side and 1 on the edge, with a size of 50% of the permitted sound knots.	Tolerated on 15 % of the length of a piece with 25 mm of thickness	Tolerated if the length does not exceed 30% of the piece.	2 gum pockets of 50 mm on the poorest meter - bark pockets of 100 mm. Slope of grain must not exceed 1 cm per 10 cm of length - split end of 10% of the piece's width - lightwood equal to 5% of the piece's volume.

 

GRADE B (old classification V)	Knots	Shakes	Wane	Other imperfections
	5 sound knots per side and 3 per edge. The size of these knots must not exceed 60 mm per 75 mm of thickness and 225 mm of width. 3 knot clusters, dead, barkringed or unsound knots are admitted on the edge, with a size of 70% of the permitted sound knots.	Tolerated per 25 % of the length of a piece with 25 mm of thickness	Tolerated if the length does not exceed 40% of the piece.	2 gum pockets of 100 mm on the poorest meter - bark pockets of 200 mm. Slope of grain must not exceed 1 cm per 10 cm of length - split end of 30% of the piece's width - light wood equal to 30% of the piece's volume - blue and water stains and dote equal to 30% of the piece's volume.

 

GRADE AB or Saw-Falling (S/F)

Mix of grades A and B

 

GRADE C (old classification VI)	Knots	Shakes	Wane	Other imperfections
	6 sound knots per side and 4 per edge. The size of these knots must not exceed 75 mm per 75 mm of thickness and 225 mm of width. 4 knot clusters, dead, barkringed or unsound knots are admitted on the edge, with a size of 90% of the permitted sound knots.	Tolerated per 70 % of the length of a piece with 25 mm of thickness	Tolerated if the length does not exceed 50% of the piece.	2 gum pockets of 150 mm on the poorest meter - bark pockets of 300 mm. Slope of grain must not exceed 1 cm per 2 cm of length - split end of 50% of the piece's width - light wood equal to 70% of the piece's volume - blue and water stains and dote equal to 30% of the piece's volume.

 

GRADE D (old classification VII)

Not used for exports - not described in this document.