MTE Grading for Teak Sawn Timber

Although the Forest Department had not published a set of Rules for Teak conversions , the millers and shippers have used their traditional grades which are known and accepted in the markets at home and abroad .

The Myanma Timber Enterprise (MTE), which is reorganized from the previously-known State Timber Board(STB), taking over the extraction , milling and marketing of teak naturally, have to find grades common to the traditional offered under different marks and write up a fresh set of rules .

The present rules are based on Myanma Timber Enterprise practices and have been drawn up along the lines adopted by the Food and Agricultural Organlzation of the United Nations .

Teak conversions cover a wide range of products and it is not always possible to describe in detail the technical differences between the varlous classes , Planks boards , flitches , etc,.are usually exported in average dimensions and are mostly intended for re-conversion into rrequired sizes . On the other hand , decks , margin planks , special scantlings , flooring , etc,. which are generally known as "DIMENSIONS STOCK " have specialized uses and are usually used in sizes supplied and therefore have to follow special specification . The specifications ate therefore divided into :

General Market Specification :-applicable in the case of Planks , Boards , Flitches , etc,. intended for reconversiopn , and
Special Market Specification to cover Decks , Margin Planks , Flitches and special Scantlings .At the moment it is not proposed to include specifications of such categories as flooring strips , shingles water levels and railway keys but these may be added later if the volume of trade involved justifies their inclusion,.

Grading Officer are expected to study these rules carefully and use their best judgement in applying them , but they should not let their judgement suersede anything written specifically in the rules themselves .

A. Instructions regarding Manufacture and Measurement

Manufacture : All timbers must be well manufactured . Unless otherwise specified , pieces shall be sawn full allowing for overcut of 1/8 ( 0.30 ) in width and thickness . All ends shall be sawn squares .,
Measurement : Unless otherwise specified , timber shall be supplied in random lengths . Length will be measured in foot rising by 6 " ( 15 cm ) .Except where half inch ( 1.30 Cm) or quarter inch ( 0.6 cm )is specified , width shall be measured in full inches any extra fraction of an inch will be disregarede . Thickness shall be measured in inches , half inches , quarter inches and one - eighth inches ( or the metric equivalents ).

When average widths and /or lengths are specified in a contract , they will be determined as follows :
1. Average Length : Divide the total length in feet ( or the equivalent in metric system ) of all the pieces in a consignment by the total number of pieces . The result will be the average width in inches ( or the equivalent in metric system ) .
2. Average Width : Divide the total width in inches ( or the equivalents in metric system ) of all the pieces in a consignment by the total number of pieces . The result will be the average width in inches ( or the equivalent in metric system ) .
3. Average Thickness : Divide the total thickness in inches ( or the equivalent in metric system ) of all the pieces in a consignment by the total number of pieces . The result will be the average thickness in inches ( or the equivalent in metric system ).
4. Percentage : Unless otherwise specified , reference to percentage in these . Rules shall apply to volume.

B. Definition as applicable to these rules

Bark Pockets : Patches of bark partially or wholly enclosed within the wood ; also known as " inbark "
Beehole : Holes in the wood caused by the larvae of Xyleutes ceramica .
Black Streak or Oil . Streak : These are lines blackish in colour . These are present in some pieces which are considered a defect from the point of view of appearance but do not effect the strength of the timber .
Blemish : Any feature which mars the appearance of a piece of timber ,but does not reduce its strength and durability ( e.g . Black Streak or Oil Streak or Chalk Veins ) .
Chalk Pockets : Cavities in wood which have become wholly or partially filled with white chalky substance.
Chalk Veins : Are lines whitish in color which are present in some pieces , which may in some cases mar its appearance but do not reduce the strength of the timber .
Chacks : Separation of the wood fibre in a longitudinal direction not penetrating as far as the opposite or adjoining side of the piece . They usually develop from strain during side of the piece . They usually develop from strain during seasoning . Surface ( or seasoning ) checks and end ( or heart ) check are to be distinguished .
Defect : Is a feature natural or induced that reduces the economic Value of a piece of timber by decreasing its strength or effecting adversely its working or finishing cualities or its appearance .
Discolouraiton : Is stain or variation from the natural color of the wood , cased by fungus attack or by oxidation through long exposure .
End Cracks : End Cracks are End Splits as a result of stress and strain in seasoning .
Grain : Reiers to the direction of the fibres of the wood , and is here termed a defect if the direction of the wood elements weakens the timber or presents difficulty in planing . ( See sloping grain)
1. Curly Grain : A wavy growth of the fibres which is difficult to plane and work .
2. Wavy Grain : A wavy growth of fibre usually appearing in flatswan timber giving the appearance which , in general trade , is known as the fiddle - back grain .
3. Rough Grain : Rough appearance on the surface of piece due to certain abnormalities of growth
4. Straight Grain : The principal wood cells running airly parallel to the length of a piece .
5. Cross Grain , Slope or Inclined Grain : The principal wood cells deviating more than 10 degrees to the longithdinal axis of the piece ( one in five )
Heart Centre : The small soft core ocdurring in the structural centre of a log around which the growth jof a tree is formed ( see Shake . )
Knot : A portion of a branch which has become embedded in the wood , and shows a clear pith in sawn timber . The crass section of a knot is usually circular or oval in shape and is measured by the mean diameter . Knots are classified as follows :
1. Sound Knot : Is solid across its face and except for its own pith is as hard as or harder than the surrounding wood to which it is joined ; it shows no indication of decay and is usually darker than the surrounding wood
2. Unsond Knot ; Is a knot which is softer than the surrounding wood because it contains decay . If the decay is advanced , there may be a hole in the center of the knot .
3. Spike Knot : A portion of the cpicormie branch , found embedded in the wood , and appearing in the form of a spike on one of the broad faces .
Sapwood : It is the outer band of living cells in a tree which are engaged in sap conduction and food storage . This is often of a different color and is not so durable as heartwood .
ke : is used to describe a serious split or deep check . If it completely encircles the pith ,it is called a ring shake , if it does not completely encircle the pith , it is called a cup shake . If it extends from the pith outwards it is called a Heart or Star Shake .
Split : Split is a longicudinal separation of fibres which extend to the opposite face or the adjoining end of a piece .
Spring : Curvature such that if the piece of timber is laid on its ( tangential ) edge , it forms a flat arch .
Sun Cracks : Sun Cracks are cracks caused by surface checks . When it reaches an advanced stage , it causes a permanent separation of wood fibres attended by discolouration , along the line of the crack .
Wane ( Want ) : Is bark or the lack of wood on edge or corner of a piece of timber , usually caused by a portion of the original curved surface of a log remaining on the piece.

C. Method of Determination of Grades

Grades are determined in these rules by the cumber of permissible defects a piece of timber can carry , Permissible defects are defined for each grade ; if a piece of timber contains more defects than are allowed by the rules it is rejected .

D. General Market Specification
Scope : The following rules define the standard Grades under the General Market Specification . These are intended primarily for grading teak conversions which are generally to be re-sawn before use for any specific purpose .

Grades : Six grades shall be recognized namely : - Select Special hitherto known as Europe First Class Special hitherto known as Europe Intermediate Quality
Selected First : hitherto known as Europe Second Class
First : hitherto known as Indian First Class
Second : hitherto known as Indian Second Class
Market : hitherto known as Indian Third Class
Grade Marks : The standard grade marks shall be :
Select Special : S S
Special : S
Selected First : F
Second : II
Market : M
Mixed Grade : In case a special agreement has been made between the buyer and seller , there may be a mixed grade e.g. Special & Better or Fifty - Fifty .
Select Special : Must be free from the following defects :
1. Large knots , large beeholes , suncracks , large pitch or bark pocker , large chalk pocket , inbark , soft heart centre . sap , cross or sloping grain , shake , rough grain ( wild growth ) . splits , or serious mechanical injury , or excessively curly or wavy grain , unless otherwise specified .
2. In pieces which possess lengths pr widths not less than the average dimension of such parcel of timber . except pieces with lengths from 9' ( or the equivalent in metric system ) upward , which shall be recknot individually the following defects will be allowed : - - one knot ? ( 1.30 cm) in diameter , not penetrating to the other side , or one beehole ? " ( 0.6 cm ) in diameter not penetrating to the other side and pieces carrying each of such defects should not exceed 5% of the total number of pieces in the parcel .
Special : Must have one broad side and one edge free of defects . The following defects will be permitted on the worse sides: -
1. Knot : One knot ? ( 1.9 cm ) in diameter not penetrating to the other side or two knot 2 ? " ( 1.3 cm ) in diameter provided that the diahance between the two defects is at least 50% of the length of the piece and that they do not penetrate to the other side . These defects are allowed in pieces of 6' ( 1.82 m ) & up in length . For pieces below 6' ( 1.82 m ) & up in length . For pieces below 6' ( 1.82 m ) in length , only one knot up to ? " ( 1.9 cm ) is allowed . A corner knot appearing on one side and on the adjacent edge counts as one only :
2. Beeholes : Two beeholes of ? ( 0.6 cm ) in diameter not penetrating to the other side provided that the distance between the two defects is at least 50% of the length of the piece . These defects are allowed in pieces of 6' (1.82 m ) & up in length . For pieces below 6' ( 1.82 m ) in length only one beehole up to 3/8 " ( 0.95 cm ) in diameter will be allowed . A corner beehole appearing on one side and on the adjacent edge counts as one only .
3. Knot and Beehole combined : One knot ? ( 1.9 cm ) in diameter will be allowed provided that the distance between the two defects is at least 50% of the length of the piece and that they do not penetrate to the other side .
4. Sap : In pieces of 4" ( 10 cm ) & up in width which contain either one knot of diameter not exceeding ? " ( 1.9 cm ) or one beehole of diameter not exceeding 3/8 " ( 0.95 cm ) and is free from all other defects , a small bright sap not exceeding ? " ( 1.30 cm ) in width and ? " ( 0.60cm ) in thickness may be allowed . ( In pieces below 4" ( 10 cm ) widths , a small bright sap not exceeding ? " ( 1.30 cm ) in width and ? ( 0.60 cm ) in thickness will be allowed if it does not contain any other defect .
  
  Pieces carrying each of such defects as restricted in this grade should not exceed 10% of the total number of pieces in a parcel .
  
  Curly Grain and Wavy Grain : Curly grain and wavy grain timber is allowed , but it should altogether not exceed 5% of the number of pieces in the parcel .
Selected First : The following defects will be permitted in the Selected First Quality Grade .
1. Knot : One sound knot up to 1" ( 2.60 cm ) in diameter not penetrating to the other side.
  Or
  Two sound knots one up to ?" ( 1.9 cm ) in diameter and another sound knot up to ?" ( 1.30 cm ) in diameter , provided that the distance between the two defects is at least 30% of the length of the piece and that they do not penetrate to the other side . In the case of sound knots, the diameter should be half that of the sound knots permitted in this grade .
2. Beehole : Two beeholes of 3/8" ( 0.95 cm ) in diameter will be allowed and that the distance between the two defects is at least 30% of the length of the piece and that they do not penetrate to the other side .
3. Knot and Beehole combined : One sound knot ?" ( 1.9 cm ) in diameter and one beehole 3/8" ( 0.95 cm ) in diameter will be allowed provided that the distance between the two defects is at least 30% of the length of the piece and that they do not penetrate to the other side .
4. Sap : In pieces of 4" ( 10" cm ) & up widths which contain either one knot of diameter not exceeding ?" ( 1.9 cm ) or one beehole of diameter not exceeding 3/8" ( 0.95 cm ) and is free from all other defects , a small bright sap not exceeding ?" ( 1.30 cm ) in width and ?" ( 0.60 cm ) in thickness may be allowed .
  
  ( In pieces below 4" ( 10 cm ) widths , a small sap not exceeding ?" ( 1.30 cm ) in width and ?" ( 0.60 cm_) in thickness will be allowed if it does not contain any other defect)
5. Sun Cuacks : Occasional narrow sun cracks , less than 1/8" ( 0.30 cm ) in width and with an aggregate length of not more than 30% of the length of a piece are allowed .
6. Pitch Pocket or Bark Pocket or Cahlk Pocket : Up to three small pitch pockets or bark pockets or chalk pockets with a mean diameter not exceeding ?" ( 0.60 cm ) if they are round or oval , and 1" ( 2.60 cm ) in length if the width does not exceed ?" ( 0.30 cm ) are allowed on any side of the piece.
  
  Pieces carrying each of such defects as restricted in this grade should not exceed 10% of the total number of pieces in a parcel .
7. Curly Grain ; Curly grain timber is allowed , but it should not exceed 5% of the total number of pieces in a parcel .
First : The following defects will be permitted in First Quality Grade .
1. Knots : Same as for Selected First .
2. Beeholes : Same as for Selected First .
3. Sap : Same as for Selected First .
4. Knot and beehole combined : Same as for Selected First .
5. Black Streaks or Oil Streaks : Small black streaks appearing on the surface are permitted provided they do not total spoil the appearance of the timber .
6. Curly Grain : Curly grain timber is allowed but it should not exceed 10% of the number of pieces in the parcel .
7. Sun Cracks : Occasional narrow sun cracks , less than 1/8" ( 00.30 cm ) in width and with aggregate length of not more than 40 % of the number of pieces in a parcel .
8. Pitch Pocket or Bark Pocket : Up to three small pitch pockets or bark pockets with a mean diameter not exceeding 3/8" ( 0.95 cm ) if they are round or oval ., and 1" ( 2.60 cm ) in length if the width does not exceed 1/8" ( 0.30 cm ) are allowed on any side of the piece provided the number of pieces containing such defects do not exceed 15% of the number of pieces of pieces in a parcel .
Second : Timber in this grade may carry the following defects :
1. Knot : One sound knot 1 ?" ( 3 cm ) in diameter , or one sound knot 1" ( 2.60 cm ) in diameter and another knot ?" ( 1.90 cm ) in diameter provided that the distance between the two defects is at least 20% of the length of the piece . In case of unsound knots , the diameter should be half of that allowed for sound knots .
2. Beehole : Two beehole of ?" ( 1.30 cm ) in diameter will be allowed provided that the distance between these two defects is at least 20% of the length of the piece.
3. Combined Defects : One sound knot 1 ? " ( 3 cm ) in diameter and one beehole ?" ( 1.30 cm )n in diameter or the equivalent in smaller knots or holes can be allowed .
4. Pitch Pocket or Bark Pocket or Chalk Pocket : Pitch Pocket or chalk pocket numbering up to four or size not exceeding ? " ( 1.30cm ) in mean diameter if its shape is round or voal or , if its shape is linear not exceeding 1 ? " this also applies to its equivalents of smaller sizes.
5. Black Streaks or Oil Streaks : Black streaks or oil streaks are permitted in this grade without any limit .
6. Sap : Sapwood not exceeding 33 ? % of the width and of the thickness will be allowed provided that the piece is free from all other defects . If the piece of timber carries other defects mentioned above in addition to the sap , the amount of sapwood for both width and thickness should be the same as in the first Quality.
7. Curly Grain : Curly Grain timber is allowed without any limit in this grade .
  
  Pieces carrying sloping grain , cracks , sun cracks and any other minor defects should not exceed 15% of the number of pieces in the parcel .
8. Sun Cracks : The size and quantity of the Sun Cracks allowed should be the same as in First Quality . The aggregate length of the Sun Cracks allowed in each piece should not exceed 50% of the length of the particular pliece.

E. Market
Any conversion poorer that those described above

F. Special Market Specifications
These specifications intended for dimensions stock such as Decks and Margin pieces , shall have only one grade in each case .

Grade Marks : The standard Grade Marks shall be DK for Decks , and MG for Margin Pieces .
General Requirement : These shall be well manufactured with cross sections rectangular throughout ; sawn full , thickness and width being 1/8" ( 0.30 cm ) full to the normal dimensions at the time of milling ; fairly straight grained , sound and free from injurious worm or beeholes splits . shakes , sapwood , large knots not exceeding 1 ?" ( 3.80 cm ) diameter or unsound knots , corner knots , ingrown bark , wane , heart centres , or imperfections due to heart centre , excessive discoloration and rot , or other injurious defects , unless otherwise specified.

Decks : Upper face and the upper half of the calking edge shall be clear . One perfectly sound knot , but exceeding 1" ( 2.60 cm ) in diameter for every 10' ( 3 meter ) will be allowed . For decks of 10' ( 3 meter ) and longer up to 20' ( 6 meter ) two knots will be allowed provided that the distance between the knots is not less than one-third of the length of the piece . For decks longer than 20' ( 6 meter ) , three knots will be allowed , and the distance between each should be at least one - third o0f the length of the piece .

Spring : The extent to which spring is allowed is as follows: -

Length 12' & Under	: No spring allowed
13' to 17'	: 1" allowed
18' to 23'	: 1" allowed
24' to 29'	: 2" allowed
30' & Over	: 2" allowed

Small beehole or worm hole of not more than 3/8" ( 0.95 cm ) diameter will be permitted . The number limited and the distance of the beehole or worm holes will be the same as for knots .

Margin Pieces : Margin pieces shall conform as to quality to the requirements relative to Teak Decking .