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INTRODUCTION

The Standard Malaysian Name for the heavy timbers of Hopea spp. (Dipterocarpaceae). Vernacular names applied include giam (Peninsular Malaysia) with various epithets, selangan (Sabah and Sarawak) with various epithets and other localised names too numerous to list here. Major species include H. ferrea, H. helferi, H. nutans, H. pentanervia and H. semicuneata. The sapwood is yellow and is poorly defined from the heartwood, which is yellow with a greenish tinge when fresh and turns deep red-brown on exposure.

Also known as Koki:r (Cambodia); Balau (Indonesia); Hin, Mai khaen fay and Mai la en (Laos); Thingyan (Myanmar); Heavy hopea (Papua New Guinea); Saplungan and Yakal (Philippines); Krabok-krang, Lao Tao, Takian Hin, Takian-Nu and Takian-rak (Thailand); and Sao xanh (Vietnam).


DENSITY

The timber is a Heavy Hardwood with a density of 865-1,220 kg/m3 air dry.


NATURAL DURABILITY

Only one species of giam (H. nutans) has been subjected to the graveyard test to determine its natural durability under exposed conditions. Of the 59 samples tested (dimension 50 mm x 50 mm x 600 mm), all were still serviceable after two years; only 5 per cent of the test sticks were destroyed in the eighth year and 80 per cent of the test sticks were found to be still serviceable after the fourteenth year. Compared to other Heavy Malaysian Hardwoods tested under the same conditions e.g. chengal, balau and merbau, this particular species of giam seems to be more durable. The timber has therefore, been classified as very durable under Malaysian conditions (Jackson, 1960).


PRESERVATIVE TREATMENT

Desch (1957) recorded that the timber, particularly the heartwood region, is exceptionally difficult to treat with preservatives. But for a timber which is naturally durable, preservative treatment is normally unnecessary.


TEXTURE

Texture is very fine to moderately fine and even, with deeply interlocked grain.


STRENGTH PROPERTIES

The timber falls into Strength Group A (Engku, 1988).


Strength Properties of Giam

 Species


Test Condition

Modulus of Elasticity(MPa)

Modulus of Rupture(MPa)

Compression parallel to grain (MPa)

Compression perpendicular to grain (MPa)

Shear strength(MPa)

H. nutans

Green

17,900

109

67

13

13

H. helferi

Green

14,600

103

54

10

14

Air dry

16,500

122

59

11

16



 MACHINING PROPERTIES

It is easy to difficult to resaw and cross-cut. Planing is, however, easy and the planed surface is smooth.


Machining Properties of Giam

Species


Test Condition


Sawing


Planing


Boring


Turning

Re-sawing

Cross Cutting

Ease of planing

Quality of finish

Ease of boring

Quality of finish

Ease of turning

Quality of finish

H. helferi


Green


easy


easy


easy


smooth


easy


smooth


-


-


Air dry


easy


easy


easy


smooth


easy


smooth


-


-

H. nutans


Green

slightly difficult


difficult


easy


smooth

slightly difficult


smooth


-


-


Air dry


difficult


difficult


easy


smooth

slightly difficult


smooth


difficult

smooth to rough




NAILING PROPERTY



Nailing property is rated as very poor.


AIR DRYING

The timber seasons very slowly, with only slight end-checking, splitting and surface-checking as the main sources of degrade. 13 mm thick boards take approximately 6 months to air dry, while 38 mm thick boards take 8 months.


KILN DRYING

Kiln Schedule B is recommended.

Kiln Schedule B

Moisture Content (%)

Temperature (Dry Bulb)

 Temperature (Wet Bulb)

Relative Humidity (%) (approx.)

 'F

'C

'F

'C

Green

105

40.5

101

38.0

85

40

105

40.5

99

37.0

80

30

110

43.5

102

39.0

75

25

115

46.0

105

40.5

70

20

130

54.5

115

46.0

60

15

140

60.0

118

47.5

50



SHRINKAGE

Shrinkage is average to high, with radial shrinkage ranging 1.4-2% and tangential shrinkage ranging 2.6-4.4%.


DEFECTS

Though the form of the trees is sometimes poor, giam timber is generally free from major defects. Minor defects of the timber include occasional attack by 'pin' hole, powder post and longicorn beetles. Resin and bark pockets may also be found in the timber. The sapwood, which is light in colour, is sometimes attacked by sap-stain fungi.  


USES

The timber is suitable for all heavy construction, marine construction, ship and boat building (keels, keelsons and framework), posts, beams, joists, rafters, flooring (heavy traffic), decking, fender supports, mallets, vehicle bodies (framework and floor boards), heavy duty furniture, cooling tower (structural members), power-line poles, railway sleepers, columns (heavy duty), door and window frames and sills, tool handles (impact), telegraphic and power transmission posts and cross arms, container floor boards and heavy duty laboratory benches.


Information shared by "mtc.com.my". 

Giam

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