TIMBER GRADING

Hokitika Guardian, 27 June 1928, Page 1

TIMBER GRADING

NEW CLASSIFICATIONS. (1) The grading of timber cannot be considered an exact science, because it is based on the usual inspection ol each piece and on tlie judgment of the grader. The provisions of these specifications, however, are sufficiently explicit to establish o per cent, below grade as a reasonable variation between graders. (2) To the extent in which differences in quality of timber, in conditions of manufacture, and in the uses to which the product is put, will, in practical application permit, the basis provisions for the grading of timber shall be uniform. (3) The grade of timber, rough or surfaced two sides, shall be determined from the best side of the piece. Timber .surfaced one side shall be graded from the surfaced side. The reverse side of the piece in either ease should not be of such a nature as to interfere with the use of the piece iu the grade intended. The reverse side of tlie higher grade should more nearly' approach the best side in quality. (4) These rules prescribe the number and extent of defects and blemishes permitted in the poorest pieces admissible in each grade. (5) The number of defects and blem-

I I B 1 t (1) For tiic purpose of simplification of sizes and grades and of equalising the grades of a similar name among species used for similar general purposes timber shall be classified in respect of principal uses. (2) In all grades superior to “Building B” the grading is based upon the use of the entire piece. SIZE CLASSIFICATION. The following size definitions are made merely for referring in definitions in order that the more preciso definitions may bo applied according to the different uses for which the varying sizes are usually applied. O) Battens:—-Timber less than 1J inches thick and under 4 inches wide. (2) Scantlings:—Timber from 1} inches to 6 inches thick by 3 inches up to G inches wide. (3) Boards: —Timber less than 1-J inches thick by 4 inches or over in width. (-1) PI aides : —Timber from 1£ inches to -I inches thick by over 6 inches wide. (•">) Heavy Timber :—-Timber over G inches thick by over 6 inches wide. The standard commercial names for timber cut from the principal species of New Zealand trees, as shown in attached Appendix A, shall be used in tbo formulation of timber (grading rules and in the construction of contracts and the terms of purchase and sale of timber tliere'under. CLASS AND GRADE STANDARDS.

ishes permitted varies as the area of the piece to be graded increases or diminishes in respect to the standard size specified, but the size of the defects .must not exceed that allowed by the grading rules. (6) When defects or blemishes, or combination thereof, not described in tbe.se grading rules are .encountered, they will be considered as equivalent to described defects according to their damaging effect upon the piece under consideration. TIMBER. CLASSIFICATION.

(1) Grade standards are adopted for timber, either, or both, on tho basis of quality and uses (or size); and iu respect of some grades the same rules may embrace one or more of those main bases.

(2) For the purpose of grading, commercial timber is divided into three distinct classes, viz:—“Heart,” “Medium,” and “Ordinary.” (3) In respect,,of Rimu, Miro, Matai and Totara: The classes' “Heart,” “Medium,” “Ordinary,” refer to the heart as follows:—“Heart” must contain 100 per cent heart woo'd. “Medium” must contain not less than 50 per cent heart wood iir any piece and must contain not less than 25 per cent heart wood in any cross section.

“Ordinary” may contain less than 50 per cent, or may be entirely free from heart wood.

(4) The foregoing three main classes are each subdivided into the following six grades*—“Clean,” “Dressing A” “Dressing B,” “Building A,” “Building B” and “Common.” DESCRIPTION OF GRADES.

(1) “Clean” grade is specially selected timber free from defects and blemishes on all faces. (2) “Dressing ■A” is suitable on one face, or one face and fine edge, for natural finish, and may contain a limited number ol blemishes (not more than two in every three feet of super face) but no defects on one side, but may contain “small” defects and or blemishes on the reverse side. Scantling, Planks, and Heavy, may contain a limited number of Flemishes (not more than two in every three feet of super face) but no defects and or blemishes on the reverse side and edge. (3) “Dressing B grade is suitable for paint finish or covered services, and may contain small defects and/or blemishes on one side and may contain “moderate” defects and/or blemishes oil the reverse side. Scantling, Planks, and Heavy may contain “small” defects on ‘ one sido and one edge and may contain “moderate” defects and/or blemishes on the reverse side end edge. NOTE: Any allowable defect in' either of the above “Dressing” grades must be sound.

(4)' “Building A” grade is suitable as a whole for general utility and structural purposes, and Battens, Boards and Planks may contain “moderate" defects, and/or blemishes. Scantling and heavy sizes may contain defects one degree -larger than “moderate”' defects provided they are situated outside the middle of the third length of the pieces-in - which thev : occur. *(5) “Building B” grade is suitable for coarser constructural purposes ■ such as sacking, rough lining, etc., and in Battens, .Boards and Planks may contain “moderate” defects and/or blemishes on one side and may contain “large” defects and/ or -blemishes on the reverse side. This grade allows a greater number or combination of defects than would be permissible' in.,. “Building, A” and which may cause not mope than 10 per c-ent waste in the-use ,of the piece. (6) “Common” grade is suitable for rough or temporary usages or foi fencing, and may contain “large” defects and/or blemishes.