Bamboo and Rattan/Rattan/Course-2 Unit-7

QUALITY

GRADING SYSTEMS

Grading is a crucial step in trading. It is of special significance in the trade in natural products, given the wide variations in their properties and quality. Grading rules designed to classify such products into different quality grades will ensure that their producer/processor gets optimum realization from product sold and the buyer is assured of return commensurate to the investment. Strict adherence to grading will preclude indiscriminate harvesting and reduce wastage on account of improper processing, thereby contributing to conservation of the resource.

As the stakeholders involved in the trade are many, viz., the producer, processor, exporter, importer, seller, buyer and user, distributed in the same or different countries, formulation and adoption of grading rules is a complex exercise, often requiring harmonizing of conflicting interests. Moreover, the rules should define terms employed precisely and provide for quantitative or qualitative assessment of determinants of quality.The existing criteria used in grading rattans vary between countries and determinants of grades are different. Their usefulness in international transactions is thus limited.

Current grading systems

Rattan is graded at different stages such as after collection, after processing and before marketing (see Fig. 16 & 17). Grading is applied at any or all of the different processing stages.

Fig. 16. Different stages of rattan grading.

Fig. 17. Flowchart of downstream processing and grading of rattans.

As mentioned earlier, the grading practices vary between countries. Even though attempts were made to formulate uniform grading rules for rattans (Bhat 1996), still the traditional systems of grading followed in different countries remains unaltered, as country/international standards on grading of rattans were not arrived at yet. However, the following procedures are usually adopted:

GRADING AT STAGE I

Sorting canes in the collection sites of producer countries and in trade centers (e.g. Hong Kong, Singapore, etc) is ’Grading at the First Stage’. The criteria employed are dimensions, ’hardness’ (remember, the term ’hardness’ adopted by trade has not related to the actual hardness, a mechanical property) and defect measurement

Dimensions:

a) Stem thickness – According to stem thickness, canes are broadly categorized into ’large-diameter’ and ’small diameter’ classes (see Fig. 18). Conventionally, the demarcation between these two classes in a majority of the countries is 18 mm.

Fig. 18. The large and small category of rattans

b) Stem length –This is another parameter employed. The minimum length prescribed for large diameter canes varies between 1 to 8 m with a common range of 3-4 m. Length prescribed for small diameter canes varies from 4 or 5 m to 8 m.

’Hardness’:

On the basis of ’hardness’, cane is graded into three categories.

c) Hard rattan – when bend by hand and released, springs back and regains its original form quickly

d) Moderately hard rattan – When bent by hand and released, regains its original form rather slowly and not fully.

e) Soft rattan – When bent, it cracks at the end or breaks, and if the bent rattan is released before it cracks or breaks, it regains its original form completely.

Defect measurement:

The defects usually evaluated are discoloration caused by fungi, breaks, worm holes scars, etc.

• In Indonesia, sorting canes into high and low quality classes based on defects such as fungal discoloration is common. Canes are then selected on the basis of length, 3 m for export purpose and shorter ones for local disposal. According to MFR (Ministry of Forestry) rules, the large-diameter canes are graded into two quality classes: Grade AB and Grade CD. Grade CD will be processed further for scraping or polishing to classify it into Grades CD1 and CD 2 (reject). The Grade CD 2 canes are sold in the local market while Grades AB and CD 1 will be sorted into seven different diameter classes from 14-16 mm to 28-30 mm for export purpose.
• In Hong Kong and Singapore, the imported raw rattan is sorted into the following grades based on ’hardness’ of the material: Soft, Moderately Hard and Hard rattan.

GRADING AT STAGE II (AFTER PROCESSING)

After processing, canes are graded on the basis of surface color. Whitish, yellowish or cream colored canes come under higher grades than brownish canes. The other parameters used with visual color determination are brightness and sheen/luster (glossiness). For instance, canes with bright and glossy surface are superior to that with dull and non-lustrous surface.

• In Hong Kong, Indonesia, Malaysia, Philippines and Singapore, brown or grey canes are bleached with hydrogen peroxide or other bleaching agents to give them a superior finish.
• Sulphur fumigation after washing and drying is another technique employed in South-east Asian countries to improve surface appearance. Artificial coloring and melamine coating are also applied to upgrade lower quality canes.
• In South-east Asian countries, oil curing green rattans is employed.
• In Malaysia, boiling rattans in water is employed.
• In Indonesia, for export purposes, the grading specifies the uniformity of color in round rod rattans (un-scraped) into three grades. For polished round rod rattans, color difference is also taken into consideration while classifying into three grades.

No clear cut scientific basis exists about the diverse rattan processing practices employed in the rattan rich South-east Asian countries. Effects of many of such traditional processing practices such as water boiling (Fig. 25), pressurized water jet washing of oil cured rattans, bleaching, fumigation, etc employed in the South-east Asian countries on their utilization value (physical and mechanical properties) are not well studied yet, resulting inconsistencies in the processing practices and lack of a uniform scientific processing methods that can be followed in all countries. For instance, pressurized water jet washing (cleaning to remove wax, resin and gums) practice of the oil cured rattans followed in Malaysia (Fig. 26) defeats the bonus of reduced moisture content achieved in oil cured rattans.

Fig. 25. Boiling rattans in water – A Malaysian Fig. 26. Cleaning rattan poles using

practice. pressurized water jet in Malaysia.

Instead of bleaching at green condition, some units bleach dry rattans, resulting again wetting, requiring once more drying. Similarly, some units fumigate wet rattans with burning sulphur, resulting acidic hydrolysis of wood material causing strength reduction.

No uniform practices based on scientific research are still not arrived at and got approved by International Standards Organizations. Hence, it is suggested to take care while employing these processing techniques.

GRADING AT STAGE III (BEFORE MARKETING)

In this final stage, the raw materials in both round and split forms are graded before marketing. The criteria employed include dimensions (diameter/width, thickness, length, taper, internodal length) of both round and split canes, color, brightness/luster, ’hardness’, and defects (stem bend, fungal stains, borer pinholes, bruises, checks, shakes, etc). Split canes such as flat/oval cores, peels and round cores are generally classified according to the dimensional specifications (width, length, thickness). Decay, worm holes, breakages and bruises are prohibited even in the lowest grade. The other defects such as blemishes, pin holes, checks and small bruises are permissible to different extents for specific grades. In India, as so far no official standards exists in this field, it is suggested to apply the needful quality conscious in preparing the raw material for marketing, till such standards are arrived at.

Problems with existing grading systems

It is clear that despite some similarity in the grading criteria employed in different countries, the defect measurement systems and dimensional specifications do not allow for standardization. Further, grading in these systems is based on subjective evaluations to a large extent and there are various discrepancies in categorizing the different kinds of canes.

The number of quality classes (and their notations) for marketing varies between countries. Non-availability of ’standard’ method for objective and precise color determination is another issue. The existing system of visual judgment of color has the problem with the variation of person to person color perception. Use of local paint color charts referred to for color description has also limitations. There exists ambiguity in the use of vernacular names when a particular species has wider geographic distribution (For instance, Calamus caesius is known as "rotan sega" in Malaysia and "rotan tamam" in Indonesia). Ambiguity in the use of trade/commercial names is another issue. Trade names have little relation with botanical origin and it differs from country to country and region to region. Usually commercial names are derived from the locality the canes comes from (e.g. Palembang, Sampit, etc) or by their appearance (e.g. ’sega’ – polished or smooth, rotan baru – stony, etc). There is further confusion in referring to rattans by locality and appearance or quality. For example, in Malaysia, four main groups have been recognized according to the trade name as follows: Sega (all canes with siliceous outer layer that crack and spring off when they are bent); Lunti (similar to sega except that the silica layer is removed); Ayer (non-siliceous canes); Sticks (straight lengths where stiffness and straightness are the main considerations e. g. walking sticks and furniture frames). Species classified under Sega and Lunti are identical in stem form such as Calamus caesus, C. optimus, C. trachycoleus, and C. leiocaulis. In the Philippines, round rod rattan is classified into six groups based on the trade name derived from appearance, distinguishing characteristics and species groups. They are: palasan, limuran, tumalim, olisi, sika and arorog. Grading based on different size (diameter) perceptions in different countries lead to non-standardization. In both small and large diameter canes, four or five classes are made with the increase of 2, 3, 5, 6 or 9 mm. In Thailand, diameter is measured in mm and an allowance of 2 mm for scraping large diameter canes is provided.

In brief, some of the problems that have arisen due to the absence of standard grading practices are: confusing terminology, non-standardized grading practices, improper harvesting of immature canes and production of sub-standard rattan goods as a consequence of employing improperly classified canes. Introduction of standardized grading system will have the advantages of value-addition (as graded rattan will enjoy a higher price), availability of standardized rattan worldwide and less wastage. It is in this context, INBAR initiated for proposing for a standardized grading rule for rattans (Bhat 1996).

INBAR MODEL RATTAN GRADING RULES

The recommended model grading rules has the following five essential components:

STANDARDIZED TERMINOLOGY

The standardized terminology is as given below:

Sl. No.	Terminology	Description
1	Bleached rattan	Cane which has been lightened in color by the use bleaching agents to improve surface brightness.
2	Cane	A general term of convenience for any piece or stem of round rattan.
3	Defect	An abnormality in cane which lowers its technical quality or commercial value by decreasing strength or adversely affecting its appearance and use.
4	Flat/Oval core	Flat or oval shaped material, width ranging from 2 to 10 mm, obtained from inner part (core) of the cane by peeling and splitting. This is normally used for weaving and binding.
5	Fumigated rattan	Cane which has been exposed to burning sulphur fumes for improvement of surface appearance.
6	Internode	The region between nodes of a stem.
7	Lustrous cane	Cane in which surface is bright and exhibits sheen or glossiness.
8	Mature cane	Rattan stems which has attained full structural development, and does not show any deformation or fracture during drying and bending.
9	Node	The thickened part of the stem at which leaves are attached in juvenile phase of growth.
10	Oil-cured cane	Cane which has been cured in hot oil media in green condition to impart desired surface color/appearance and prevent biological degradation.
11	Rattan	A collective term for the climbing members of a large group of Lepidocaryoid palms (sub-family: Calamoideae).
12	Rattan derivatives	Products or parts of cane resulting from rattan conversion (splitting/peeling).
13	Rattan peel	Flat or semi-circular material, the width ranging from 2 to 10 mm obtained from the peripheral portion of the cane including the skin; normally used for weaving and binding.
14	Rattan pole	Round rattan of convenient length.
15	Round core	Round material, consisting of central part (core) of rattan stem with diameters ranging from 2 to 10 mm, obtained by peeling and splitting; normally used for wicker work.
16	Round rods	Poles from which rattan skin has been removed either by scraping or by a round-rod making machine.
17	Scraped rattan	See "Round rods".
18	Seasoned rattan	Cane whose moisture content has been reduced to the specified minimum under more or less controlled process of drying.
19	Treated rattan	Cane which has been treated with preservative chemicals to prevent biological degradation.
20	Unsplit rattan	Round cane, scraped or un-scraped, but without being subjected to peeling or splitting.
	DEFECTS
21	Bend (Curvature)	Any deviation from straightness of the cane and is measured by the chord which the curvature makes between the extreme edges of deviation and by the depth at the middle portion.
22	Blemish	Any feature that mars surface appearance. Whether a particular feature is classed as blemish depends on the relevant grading rule or on the purpose for which the cane is intended.
23	Break	A separation of fibres which from one surface to the other usually perpendicular to the direction of the grain.
24	Bruise	An injury on the surface caused by harvesting operations or improper processing.
25	Check	A longitudinal fissure indicating separation of fibres along the cane length, not extending through the piece from one surface to another.
26	Hole	A cavity caused by worms (worm hole), insects (pinhole) or mechanical means.
27	Scar	Depression or any marking on the surface other than fungal discoloration.
28	Shake	A partial or complete separation between adjoining layers of tissues, as seen in end surfaces, caused by stresses developed in cutting and collecting, or in unequal drying of immature stem.
29	Other defects	Any defect not listed above but which will debar any piece from its expected utility can be considered as defect which can be identified depending on the appearance, size, location and distribution. e. g. wrinkles on the surface.

I METHODS OF CLASSIFICATION

The following criteria have been adopted in this model for evaluating the quality of the rattan:

i. Diameter class

Based on the diameter in the small end, following standard diameter classes are followed:

a) Large-diameter rattan: Unsplit cane measuring from 18-40 mm or above

b) Small-diameter rattan: Unsplit cane measuring below 18 mm

ii. Strength class

Based on the strength values obtained in mechanical testing, un-split rattans are classified as follows:

a) Strong to very strong: Static bending modulus of rupture (MOR) and or tensile strength –

ultimate tensile stress (UTS) above 70 N/mm²

b) Moderately strong: MOR or UTS 45-70 N/mm²

c) Weak: MOR or UTS below 45 N/mm²

iii. End-use class

Following five categories of end-uses are recognized for assessing utilization potential of particular grade:

a) Furniture frames

b) Furniture seats

c) Walking sticks, umbrella handles, sporting goods, etc.

d) Handicrafts/Novelty items

e) Baskets

II GENERAL CLASSIFICATION AND NOMENCLATURE OF COMMERCIAL RATTAN SPECIES

Scope

This standard provides a proforma for general classification and nomenclature of commercial rattan species in country, with information about the source of supply/distribution, properties and potential end-uses. The important rattan genera are Calamus, Ceratolobos, Daemonorops, Korthalsia, Myrialepis, Plectocomia and Plectocomiopsis.

General requirement

When a country has distinctly different agro-climatic zones with restricted occurrence of species, zonal distribution will be included in the national system.

Terminology

For the purpose of this standard, the definitions given in the "Standard Terminology" shall apply.

Classification

The listing of species suitable for each category of end-use given in the Standard Terminology will include botanical name, standard trade name, distribution (source), diameter class, weight and strength class.

Sample proforma:

Proforma for classification and nomenclature of commercial rattan species (Country/Zone)

Sl. No.	End-use	Botanical name	Trade/Local name	Distribution	Diameter	Weight	Strength
1	Furniture frames
2	Furniture seats/backs
3	Walking sticks, Umbrella handles, Sport goods, etc.
4	Handicrafts/Novelty items
5	Baskets

III GRADING RULES FOR UNSPLIT RATTAN: LARGE-DIAMETER CANES

Scope

This Standard covers the minimum requirements for trading large-diameter rattans.

Terminology

For the purpose of this standard, the definitions given in the "Standard Terminology" shall apply.

General requirements

• Canes shall have authentic botanical identity when the species are specified by the buyer.
• Canes shall be straight, round, mature and seasoned.
• Canes shall not break or develop checks and other defects in bending or any other processing stage
• Canes shall be either oil-cured or chemically treated with anti-staining fungicide, bleached or fumigated as specified by the buyer.
• Plugging or covering of visible defects shall not be permitted in any form.

Dimensional specifications

a) Length: Length shall be taken as the shortest distance in meters from one extreme

end to the other. Length shall be rounded off to the nearest lower 0.05 m. It

shall be as specified by the buyer.

b) Diameter: The minimum diameter shall be 18 mm. The standard diameters shall be

expressed in mm with a tolerance of + 3 mm for scraping. The diameter shall

be determined in the mid internode of small end. Following diameter

classes shall be adopted for trading: >40 mm, 35-40 mm, 30-35 mm, 25-30

mm, 20-25 mm, 18-20 mm.

c) Taper: The maximum taper shall not exceed 5 mm for a length of 3.5 m. Taper of

the cane shall be determined by the difference between diameters

measured in two extreme ends.

c) Internodal

length: The minimum length shall be 50 mm. It shall be taken as the shortest

distance from one node to another and expressed in mm.

Defects

Prohibited defects: Defects such as decay, worm holes, breakage and shakes shall not be

permitted.

Permissible

defects: Defects such as blemishes, scar, pinholes, checks and bruises to the extent

specified for a specific grade shall be permissible.

Appearance: Canes shall be inspected visually for color and brightness.

Grading: Based on the quality consideration in terms of appearance and the extent of

permissible defects, four grades shall be recognized as follows:

Grade	Specifications
Super Quality	Entirely (100% of specified length) free from defects, ivory white, cream or yellowish in color, uniformly bright or lustrous surfaces, internodal length greater than 100 mm.
I	Extent of permissible defects shall not exceed 15% of the specified length, ivory white, cream or yellowish in color, uniformly bright or lustrous surfaces, internodal length greater than 100 mm.
II	Extent of permissible defects shall not exceed 50% of the specified length, ivory white, cream or yellowish in color, uniformly bright or lustrous surfaces, internodal length greater than 100 mm.
III	Extent of permissible defects shall not exceed 75% of the specified length, whitish, yellowish, brown or dark brown in color, uniformly bright or lustrous surfaces, internodal length greater than 50 mm.

Inspection procedure

1) Unsplit canes shall be inspected and classified individually.

2) All large-diameter canes shall be single-scraped and chemically treated with anti-staining fungicides.

3) A minimum of 10% of the lot may be inspected at random to determine size uniformity.

Packaging and labeling

Canes shall be sorted, bundled and legibly marked according to diameter, length, grade and species. Each bundle of canes shall be labeled with the following information:

1. Trade name/vernacular name

2. Botanical name

3. Diameter/length

4. Grade

5. Origin/source

6. Number of canes per bundle

7. Name and address of supplier

8. Date of supply

IV. GRADING RULES FOR UNSPLIT RATTAN: SMALL-DIAMETER CANES

Scope

This Standard covers the minimum requirements for trading small-diameter rattans.

Terminology

For the purpose of this standard, the definitions given in the "Standard Terminology" shall apply.

General requirements

• Canes shall have authentic botanical identity when specified by the buyer.
• Canes shall be mature and seasoned.
• Canes shall not break on bending or any other processing stage.
• Canes shall be either oil-cured or chemically treated with anti-staining fungicide, bleached or fumigated as specified by the buyer.
• Plugging or covering of visible defects shall not be permitted in any form.

Dimensional specifications

a) Length: Length shall be taken as the shortest distance in meters from one extreme

end to the other. Length shall be rounded off to the nearest lower 0.05 m. It

shall be as specified by the buyer.

b) Diameter: The diameter of canes shall be below 18 mm. The diameter shall be

determined in the mid internode of the small end. Following diameter

classes shall be adopted for trading: 2-6 mm, >6-11 mm, and 11-17 mm.

c) Taper: The maximum taper shall not exceed 3 mm for a length of 4.5 m. Taper of

the cane shall be determined by the difference between diameters

measured in two extreme ends.

d) Internodal length: The minimum length shall be 50 mm. It shall be taken as the shortest

distance from one node to another and expressed in mm.

Defects

Prohibited defects: Defects such as decay, worm holes, breakage and shakes shall not be

permitted.

Permissible

defects: Defects such as blemishes, scars, pinholes, checks and bruises to the extent

specified for a specific grade shall be permissible.

Appearance: Canes shall be inspected visually for color and brightness or luster.

Grading: Based on the quality consideration in terms of appearance and the extent of

permissible defects, four grades shall be recognized as follows:

Grade	Specifications
Super Quality	Entirely (100% of specified length) free from defects, ivory white, cream or yellowish in color, uniformly bright or lustrous surfaces, easily pliable, internodal length greater than 100 mm.
I	Extent of permissible defects shall not exceed 15% of the specified length, ivory white, cream or yellowish in color, uniformly bright or lustrous surfaces, easily pliable, internodal length greater than 100 mm.
II	Extent of permissible defects shall not exceed 50% of the standard length, ivory white, cream or brownish in color, internodal length greater than 100 mm.
III	Extent of permissible defects shall not exceed 50% of the standard length, whitish, yellowish, brown or dark brown in color, internodal length greater than 50 mm.

Inspection procedure

1. Unsplit canes shall be inspected and classified individually.

2. All small-diameter canes shall be chemically treated with anti-staining fungicides.

3. A minimum of 10% of the lot may be inspected at random to determine size uniformity.

Packaging and labeling

Canes shall be sorted, bundled and legibly marked according to diameter, length, grade, trade name and species. Each bundle of canes shall be labeled with the following information:

1. Trade name/vernacular name

2. Botanical name

3. Diameter/length

4. Grade

5. Origin/source

6. Number of canes per bundle

7. Name and address of supplier

8. Date of supply

V. GRADING RULES FOR SPLIT RATTAN (CANE DERIVATIVES)

Scope

This Standard covers the minimum requirements for trading the split rattan (cane derivatives) which include round cores, flat or oval cores (Fig. 27) and peels (Fib. 28).

Fig. 27. Rattan cores.

Terminology

For the purpose of this standard, the definitions given in the "Standard Terminology" shall apply.

General requirements

• Cane derivatives shall be obtained from mature and seasoned canes and be pliable.
• Split rattan shall be derived from either oil-cured, fumigated, bleached or chemically treated with anti-staining fungicides as specified by the buyer.
• Plugging or covering of visible defects

shall not be permitted in any form;

the surface shall be smooth.

• Diameter of round cores or width of flat

and oval cores and peels shall be uniform

throughout the length. Fig. 28. Rattan peels

a) Length: Length of split canes shall be taken as the shortest distance in meters from

one extreme end to the other. Length shall be rounded off to the nearest

lower 0.05 m. It shall be as specified by the buyer.

b) Diameter: Diameter of round canes shall be from 2 to 10 mm with a tolerance of + 0.5

mm.

c) Width: Width of flat or oval core and peels shall be 2 to 10 mm.

d) Thickness: Thickness of flat or oval core and peels shall be from 1 to 6 mm.

Defects

Prohibited defects: Defects such as decay, worm holes, breakage and shakes shall not be

permitted.

Permissible

defects: Defects such as blemishes, scars, pinholes, checks and bruises to the

extent specified for a specific grade shall be permissible.

Appearance: Canes shall be inspected visually for uniform color and brightness or lustre.

Grading: Based on the quality consideration in terms of appearance and the extent of

permissible defects, two grades shall be recognized as follows:

Grade	Specification
I	Entirely free from defects, whitish in color.
II	Extent of permissible defects shall not exceed 15% of standard length; whitish, yellowish or brown in color.

Inspection procedure

1) Split canes shall be inspected and classified individually.

2) A minimum of 10% of the lot may be inspected at random to determine size uniformity.

Packaging and labeling

Cane derivatives shall be sorted, bundled and legibly marked according to diameter/width, length and grade. Each bundle shall be labeled with the following information:

1. Trade name/vernacular name

2. Botanical name

3. Size (diameter/width and thickness)

4. Grade

5. Origin/source

6. Name and address of supplier

7. Date of supply

Other conditions

1. The cane derivatives shall be coded according to the measurement. E. g. round cores

measuring 2 mm shall be labeled "round core ≠2" or "peels ≠5".

2. If bleaching or any other special treatment is given, it can be specified to indicate the

special quality to become a sub-classification of the particular grade.

Fig. 29 illustrates the inter-linkage of various steps in the secondary processing of rattans.