More about Teak | Teak Log Grading | Teak Log Business | Teak Benches

Teak Log Grading

Introduction
Grading is a value adding process as " adding value" is an action that adds worth to something through a specific process. Properly graded timber gives a value of worthiness and satisfaction to the buyer and graded timber of any species enjoys higher prices than ungraded timber. In the early days not many items of timber were traded and grading was mainly by rule of thumb.

Most countries and regions have their own sets of grading rules with different rules for different species; for softwoods and hardwoods. For example, the National hardwood Lumber Association(NHLA) Rules from the United States, the British Columbia Lumber Grading and Quebec Grading Rules from Canada, the Finish Grading Rules and the Malayan Grading Rules(MGR) are some of the well-known rules, to name a few. As a major teak producer, Myanmar has its own sets of grading rules for teak and grading of teak logs and lumber in Myanmar is done according to these rules. Until now there appears to be no collaboration regarding grading among the teak producers in the Region. Teak, whether in the rough or processed is still a natural product, and growth conditions are mainly influenced by soil and climate. Until a wonder technique has been perfected to produce finer specimens of trees, grading rules will remain the arbiter of what a piece of timber is worth.

Jungle Rejection Rules
The origin of the first modern grading rules for teak logs in Myanmar can be traced back to 1936. The Forest Department established the "Logging Rules and Standard for Jungle Rejection of Teak Logs" and the rules mention the measuring system. Logging system and system of rejection in the jungle. In short, the rules specifiy the calculation of defects for obligatory and optional timber. Mention of Grades is not noted in these rules.

Gallant Rules
The " Standard for Jungle Rejection " was followed in April 1998 by " Classification of Teak Logs ", popularly known as "Gallant Rules", as they were prepared by Mr. M.M. Gallant, Forest Economist of the Forest Department. This classification covers five grades; viz., five star( or AY), four star, three star, two star and one star. Like the standard for Jungle Rejection, and the Gallant Rules deduct five cubic feet per defect for scaling purposes. Star classes are graded according to the defect value and the limits determining the star class of a log are given in Table 1.

Table 1: - Star Classes and defect values
Star Class Min. Length
(Ft)
Min. Girth
(Ft)
Min.Volume
(Cu.Ft)
Defect
AY (5*) 15 6 - 0.5/50 Cu.Ft
4* 15 5 30 1.0/50 Cu.Ft
3* 12 5 30 2.0/50 Cu.Ft
2* 10 4 20 3.0/50 Cu.Ft
1* 10 4 20 5.0/50 Cu.Ft

Note - Logs are graded by calculating the defects per 50 Cubic Feet.

Grading Rules for Teak Veneer Logs
The late 1950s saw the rise of the teak veneer market started much earlier. The quality of the logs harvested then was very good and therefore logs graded under the Gallant Rules were also acceptable as veneer logs, mainly because of the superior quality of the logs. Logs inferior in quality to those harvested earlier, increased in quantity as time passed. Market conditions also pinpointed defects previously not recognized. Aesthetic value is now being considered in addition to other quality defects. A new set of rules prepared by the Myanma Timber Enterprise (MTE) came into being are called the "Grading Rules for Teak Veneer Logs" , and are currently applied. Defects considered in the Galant Rules and the Veneer Log Rules are shown below as comparisons:

Gallant Rules
Bear Bites; Bee Hole; Bend; Bird Holes; Buttress( no defcets); Doyo; Drag Hole; Ellipse; Flute; Holes(End); Knots; Shakes; Shatter; Snout(no defects); Sun Cracks, Inbark; Twist.

Veneer Log Rules
Bee Hole; Bump; Curvature; Elephant Skin; End Flute marks; Flutes; Green Band; Heart(Diagonal, Double, Spongy, Hole, End); Inbark; Knots(sound, Pin); Pig Eyes; Pitch Pockets; Shape(Elliptical, Triangular); Shake(Ring, Cup); Splits; Sun Cracks; Twist; Wavy Grain; Interlocked grain; Black Spots; sapwood pockets and Syphilis)

Permissible defects are scheduled according to the location and magnitude. These defects are then classified as either mild or serious. One serious defects (S) equals to mild(M) defects, and each grade limits 3(S) or 6(M). In the Veneer Log Rules, log scaling, i.e. estimating the net contents of a log, which equals the gross or full contents less deduction for defects, is not taken into account. This is one difference from the preceding rules but like its predecessors, each log has to be graded separately.

One of the disadvantages in the log trade is that one has to sell only what was extracted. Up to the mid-seventies, a larger percentage of First, Second and Third quality logs were available for export. What was not exported in log form was used in the local mills. The 1980s witnessed an entirely different scenario when fewer veneer logs were obtained and more sawing-quality logs become available.

The need for introducing rules for sawing quality teak logs that do not fit in the previous rules engendered a new set of rules for sawing quality logs that are inferior to the 1 Star Class. Gallant Rules require that logs are to be butted clean at both end. The same applies to veneer logs. But, the sawing quality logs sold today are unbutted and offered for sale as they come out of the forest. A comparison of dimensions is shown in Table (2).

Table 2: - Comparison Between Galant Rules and Veneer Log Rule
Gallant
Rules
Min Dimension
Length x Girth
Veneer Log Rule Min Dimension
AY L15' x G6' Special L15' x G6'
4* L15' x G5' - min.30Cft First L8' x G4'-2"
3* L12' x G5' - min.30Cft Second L8' x G4'-2"
2* L10' x G4' - min.20Cft Third L8' x G4'-2"
1* L10' x G4' - min.20Cft Fourth L8' x G4'
- - Sawing Grade - 1 L8' x G5'
- - Sawing Grade - 2 L8' x G5'
- - Sawing Grade - 3 L8' x G3' to 4'-11"
- - Sawing Grade - 4 L8' x G4'

Note - In veneer logs there is no minimum volume(vol) or cubic content specified provided that the length(L) and Girth(G) are met.

The sawing Grade Rules calculate the defect value as in Gallant Rules. But, there is no log scaling. Each Grade allows a fixed defect value. Grading is done according to the defect value considering the category of grade a log will fall into after the length and the girth are taken.

In addition, teak logs originating from different areas have different values. Area consciousness on the part of the buyers is very pronounced in this particular species. Teak logs from areas with heavy rainfall are less favored than logs from that of scanty rainfall. For instance, teak log from Yamethin, Pyinmana, Pyay, Minbu and Yaw are extremely popular. It has alos been noticed that teak from Northen Shan State, and Momeik are also favoured. The reason for the partiality is that there are no typical defects in teak logs from these areas and the colour, stripe and conformation of the logs rate from Good to Very Good. Incidence of beeholes is markedly less in logs from the above mentioned area. Area-wise characteristics of Myanmar Teak logs are mentioned Table (3) as bellows:

Table 3: Area-wise characteristics of Myanmar Teak Log
No Area Typical defects Nature of
Stripe
Sawing
Yield %
Colour Formation
1 Yamenthin Not Promonent V.Good 85 V.Good Good
2 Pyinmana Not Prominent Good 60 V.Good Good
3 Meikhtila Heavy Suncracks V.Good 95 V.Good Fair
4 Pyau Not Prominent V.Good 90 V.Good Good
5 Minbu heavy Suncracks V.Good 90 V.Good Good
6 Pyin-Oo-Lwin Not Prominent V.Good 85 Medium Good
7 Aunglan Heavy Suncracks V.Good 90 V.Good Fair
8 Yaw Not Prominent V.Good 75 Good & Dull Fair
9 Thayet Heavy Suncracks V.Good 80 V.Good Fair
10 Zigon Not Prominent Good 50 Fair Good
11 Kayah State V.Heavy Suncracks Good 80 Dull Poor
12 N.Shan State Not Prominent V.Good 70 Good Good
13 Lr.Chindwin Not Prominent Good 60 Good Good
14 Shwebo Pitch Pocket
Black Spot
Thin 75 Good V.Good
15 Mongmeik Black Spot Good 65 Good V.Good
16 Pa-an Not Prominent Fair 60 Good Good
17 N.Taung-Oo Pitch Pocket Poor 70 Good Good
18 Kawkerik Not Prominent Poor 60 Good Good
19 Myitkyina Many Bee Holes
Heavy Pitch Pocket
Black Spot
V.Poor 10 Good Good
20 W.Katha Many Bee Holes V.Poor 40 Good Good
21 Bhamo Many Bee Holes
Many Pitch Pocket
V.Poor 10 Good Good
22 E.Katha Many Bee Holes
Heavy Pitch Pocket
Black Spot
Fair 65 Medium V.Poor
23 Up.Chindwin Many Bee Holes
Heavy Pitch Pocket
Black Pocket
Fair 35 V.Poor Good
24 Myitha Heavy Pitch Pocket
Bee Holes
Black Spot
Fair 40 V.Poor Good
25 S.Toing-Oo Pitch Pocket Thin 50 Poor Good
26 S.Shan State Heavy Pitch Pocket
Bee Holes
Cracks
V.Good 95 Poor Poor
27 S.Pegu Bee Holes Thin 50 Good Good

Note - S=South, N=North,Up.=Upper and Lr.=Lower

The areas are classified as Good Area, Medium Good Area and Poor Area. Some characteristics variable on the different areas are mentioned in Table (4 ) as below:

Good Areas
Area Colour Stripe Formation Remark
Yamethin Good Little Good -
Pyinmana Good Little Good -
Meikhtila Good Many Good -
Pyi (Prome) Good Many Good -
Minbu Good Many Good -
Aung Lan Good Many Good -
Yaw Good Many Good Preferred in Hong Kong
Gantgaw Good Many Good - do -
Thayet Good Many Good - do -
Zigone Good Little Good Preferred in Japan

Medium Good Areas
Area Colour Stripe Formation Bee Hole Remark
Mabein Good Medium Good - -
N.Katha Poor Fair Good Fair -
Shan Good Good Good - Favor of
HK & Japan
Chindwin Good Many Good - Favor of HK
Shwebo Good Many Good - Favor of HK
Myittha Poor Little Good - Favor of Japan
Taung-Oo Poor Little Good - Favor of Japan
Bago (Pegu) Poor Little Good - Favor of Japan

Poor Areas
Area Colour Stripe Formation Bee Hole Remark
Kayah Poor Many Poor - -
Pa-an Poor Fair Fair - -
N.Taung-Oo Poor Fair Poor - -
Myitkyina Poor Many Poor - -
Bhamaw Poor Poor Fair - -
Kyankhin Poor Fair Fair - -
U.Chindwin Poor Fair Poor - -
Thibaw Poor Many Poor - -

Note - N=Northern, S=South, U=Upper

Myanma Timber Enterprise (MTE) has specified the Defects Classification as follows:

Major Defects
Bee Holes, Green Band, Branch, Heart Hole, Doyo Hole, Pitch Pocket, Double Heart, Wavy, Bump, Twist, Culvature Diagonal Heart.

Minor Defects
Cup Shape, Ring Shape, Flute, Inbark, Sun Crack, Spongy, Pinknot, Black Spot, Elephant Skin, Triangle shape, Felling crack, Elliptical shape.

Additional Defects
Inbark hole, Star crack, Waving ring, Ring close, Deform Gallstore, Heart crack, Side hole, water stain, Flute mark, Color dark, Heart spongy, Pig eye, White spot, White band.