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Rubber Specification
Natural Rubber Packing Specifications

 

All natural rubber of the types and grades specified in Part II must be packed in accordance with the following specifications.
It is not intended to discourage special packing in wooden cases, paper bags, or other containers where buyers specify or prefer greater protection of the rubber.
Of particular note in the following specifications are the requirements regarding uniform bale weights. The use of white powder of the types specified in Section 6 of Part V is strictly limited to the requirements listed in the following specifications.  

Ribbed Smoked Sheets

(a) All Ribbed Smoked Sheets shall be packed in rubber covered bales.
(b) The maximum weight of each bale should be 250 lbs. (113.5 kg) net per five cu. Ft. (0.142 m3) outside measurements. The minimum weight of each bale shall be 224 lbs. (101.7 kg) net, except where lower weights are specified in the buyer's contract. Each bale within a given shipment covered by a single bill of lading shall be of uniform weight, except for no more than two bales of lesser weight to provide for exact contract weight.
(c) Each bale must be wrapped on all sides and corners with equal or higher quality rubber of the same type. Double wrapper sheets must be used if wrapper sheets contain holes. No metal bands or wires or non-metallic binders shall be placed under wrapper sheets.
(d) For No. 1X, and No. 2 Ribbed Smoked Sheets, the outside of the bales shall be lightly dusted with powder before applying the wrapper sheets to prevent sticking. Powder must not appear in any other part of the bale. For Nos. 3, 4, and 5 Ribbed Smoked Sheets, no powder shall be used on the inside of the wrapper sheet, nor in any other part of the bale.
(e) To overcome adhesion in transit and also to provide proper background for stenciling of colored shipping marks, the outside of the wrapper sheet must be completely entirely painted on all six sides with one coat of the official bale coating solution. No other bale coating solution may be used, except where such use has been specifically accepted by the buyer. (The formula for this solution is shown in Section 7).
(f) Bale markings, as required in Section 9, shall appear on not less than two adjoining sides of the bale.  

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Thick Pale Crepes

(a) Thick Pale Crepe types must be packed in burlap-covered bales.
(b) The maximum weight of the rubber in each bale should be 224 lbs. (101.7 kg.) net per five cu. ft. (0.142 m3) outside measurements. The minimum weight of each bale shall be 160 lbs. (72.6 kg) net, except where lower weights are specified in the buyer's contract. Each bale within a given shipment covered by a single bill of lading shall be of uniform weight, except for no more than two bales of lesser weight to provide for exact contract weight.
(c) Before covering with burlap, each bale shall be properly strapped by using not less than three iron bands of a minimum width of 3/8" (1.6 cm). These bands should preferably be galvanized or similarly protected to prevent rust.
(d) Nothing inferior to new 12-ounce (0.34 kg) hessian shall be used for covering. Second-hand rice or sugar bags, equal to or superior to new 12-ounce (0.34 kg) hessian, without holes or patches, provided they are thoroughly cleaned, are also satisfactory. Use of burlap previsouly treated or processed to prevent mildew is strictly prohibited. Before application of the burlap cover, the surfaces of the bale must be evenly dusted with sufficient powder to prevent adhesion of the burlap lint and fluff to the rubber. No other powder shall appear in the rubber.
(e) Markings must be placed on two adjoining sides of the bale in accordance with the bale marking requirements given in Section 9.  

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Thin White and Pale Crepes

(a) The maximum weight of the rubber in each bale should be 224 lbs. (101.7 kg) net per five cu. ft. (0.142 m3) outside measurements. The minimum weight of each bale shall be 160 lbs. (72.6 kg.) net, except where lower weights are specified in the buyer's contract. Each bale within a given shipment covered by a single chop mark shall be of uniform weight, except for no more than two bales of lesser weight to provide for exact contract weight.
(b) Each bale must be wrapped on all sides and corners with equal or higher quality white or pale crepe. Multiple plies of white or pale crepe shall be used in the wrapper so as to insure that the interior rubber shall be protected. The surfaces of the bales must be lightly and evenly dusted with powder before application of the wrappers. Powder shall not be used in any other part of the bale.
(c) Three iron bands of a minimum width of 5/8" (1.6) cm), preferably galvanized or similarly protected to prevent rust, on the outside of the wrapper sheet, are permissible, but wire shall not be used. No metal bands or wire or non-metallic binder shall be used under the wrapper sheets.
(d) The rubber-covered bales may be shipped in this form or they may be covered with coated burlap.
(e) To overcome adhesion of the bales in transit when shipped without burlap coverings, the outside of the wrapper sheet must either be heavily powdered or painted with one coat of the official bale coating solution.
(f) Nothing inferior to new 12-ounce (0.34 kg.) hessian shall be used for covering. Second-hand rice or sugar bags, equal to or superior to new 12-ounce (0.34 kg) hessian, without holes or patches, provided they are thoroughly cleaned, are also satisfactory. Use of burlap previously treated or processed to prevent mildew is strictly prohibited. Before application of the burlap cover, the surfaces of the bale must be evenly dusted with sufficient powder to prevent adhesion of the burlap lint and fluff to the rubber. To prevent such adhesion all coverings may first be liberally coated with a proper mixture of sago flour, water and silicate of soda to prevent the covering from adhering to the rubber. A generous application of this solution must be given to insure proper absorption. The burlap should be thoroughly dried before applying it to the rubber.
(g) Markings must be placed on two adjoining sides of the bale in accordance with the bale marking requirements given in Section 9.  

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Standard Flat Bark Crepe

(a) The maximum weight of the rubber in each bale should be 224 lbs. (101.7 kg) net per five cu. ft. (0.142 m3) outside measurements. The minimum weight of each bale shall be 160 lbs. (72.6 kg.) net, except where lower weights are specified in the buyer's contract. Each bale within a given shipment covered by a single chop mark shall be of uniform weight, except for no more than two bales of lesser weight to provide for exact contract weight.
(b) Each bale shall be properly strapped by using not less than three iron bands of a minimum width of 5/8" (1.6 cm.). These bands should preferably be galvanized or similarly protected to prevent rust. Wire shall not be used.
(c) Powder may appear on the bale only as specified below. Packing is acceptable in the following three different ways:

1 Unwrapped Coated Bales
All surfaces of the bale should be covered with no more than two coats of the official coating solution. Two burlap patches or thin light-colored natural rubber patches of suitable size must be placed under the iron strapping on opposite sides of the bale for purposes of identification marks.

2 Rubber Wrapped Bales
Each bale must be wrapped on all six sides and corners with Nos. 1,2,3 or 4 Thin Brown Crepe. The iron bands should be placed on the outside of the wrapper sheets. To overcome adhesion of the rubber wrapped bales in transit, the outsides of the bale must either be heavily powdered, or painted with no more than two coats of the official coating solution. Two burlap patches or thin light-colored natural rubber patches of suitable sizes must be placed under the iron strapping on opposite sides of the bale for the purposes of identification marks.

3 Burlap Wrapped Bales
Nothing inferior to new 12-ounce (0.34 kg.) hessian shall be used for covering. Second-hand rice or sugar bags, equal to or superior to new 12-ounce (0.34 kg) hessian, without holes or patches, provided they are thoroughly cleaned are also satisfactory. Use of burlap previously treated or processed to prevent mildew is strictly prohibited. Before application of the burlap cover, the iron bands must be applied and the surfaces of the bale must be evenly dusted with sufficient powder to prevent adhesion of the burlap lint and fluff to the rubber. No other powder shall appear ni the rubber. To prevent such adhesion all coverings may first be liberally coated with a proper mixture of sago flour, water and silicate of soda to prevent the covering from adhering to the rubber. A generous application of this solution must be given to insure proper absorption. The burlap should be thoroughly dried before applying it to the rubber.

(d) To overcome adhesion of non-burlap covered bales in transit, the outside of the bales must either be heavily powdered or painted with no more than two coats of the official bale coating solution. No powder shall be used in any other part of the bale.
(e) Identification marks must appear on the two patches or on two adjoining sides of the bale when burlap covers or rubber wrappers are used, in accordance with the bale marking requirements shown in Section 9.  

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Powder Specifications

The powders considered as acceptable for use in bale coating formulations and packing of natural rubber shall be white and water insoluble inorganic substances.

They must meet the following minimum specifications when washed through the following sieves:

100% penetration through a standard U.S. Sieve No. 100 93% penetration through a standard U.S. Sieve No. 325 The screens for testing shall conform to the U.S. Standard Sieve Series Equivalents, as specified by the American Society for Testing and Materials, ASTM designation E-11-70. The specific gravity of the powders used may range from 2.60 to 3.00. They must disperse uniformly and without agglomeration upon milling. The following types, provided they are white, shall be considered as acceptable:
1. Mineral powders consisting mainly of hydrous magnesium silicate. These are generally known as talc, talcum, soapstone, magnesium silicate, steatite, fibrous talc and French Chalk.
2. Mineral powders consisting mainly of hydrous aluminum silicate. These are generally known as kaolin, Dixie Clay, Catalpo Clay, China Clay, etc.
3. Mineral or precipitated powders consisting mainly of calcium carbonate. These are generally known as whiting chalk, Paris or English White.
4. Any combination of powders listed above is permissible. Mineral powders containing calcium sulphate are not acceptable. These are generally known as gypsum or Plaster of Paris. Also, alpha quartz or asbestos fibers should not be contained in these powders.  

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Official Bale Coating Solution

A. Natural Rubber Solution Binder

lb. (0.23 kg.) clean natural rubber
1 U.S. gal. (3.8 l) solvent (specified below)
Allow the above mixture to soak for 24 hours then add U.S. gal (2.0 l) solvent and stir until uniformly mixed.
The solve that must be used is a hydrocarbon of petroleum distillate having a distillation range of 290 F (143 C) to 410 F (210 C). The specific gravity at 60 F (16 C) ranges from 0.766 to 0.830. The flash point in a closed cup ranges from 90F (32C) to 105F (40).
Known trade names of this material as distributed in Southeast Asia are as follows: Shell Oil - "Mineral Turpentine" and "Low Aromatic White Spirits." Standard Vacuum Oil - "Vanolene."

B. Coating Mixtures

4 U.S. gal (15 l) solvent
16 lbs. (7.3 kg) natural rubber solution binder
Up to 48 lbs. (21.8 kg) fine white powder as specified in Section 6.
This formula provides enough for coating approximately 75 bales having 17.5 ft.2 (1.63 m2) surface area. The solids content of this quantity of coating mixture (with 48 lbs. (21.8 kg) of fine white powder) if evenly distributed on 75 bales, would result in approximately 10.5 ounces (0.29 kg) of solids per bale.
The coating after drying shall impart a complete lack of adhesion when two treated rubber surfaces are compressed against each other.
The following ingredients are unsatisfactory for use either as filters or binding materials and their use is not permitted:

(a) Starch materials
(b) Glue materials
(c) Resin materials, except "damar resin"
(d) Calcium sulphate

Experience has shown that powders available for sale in the rubber producing areas vary as to their weight per unit volume. If lighter weight varieties of powder are used, strict adherence to the concentrations in the above formula may result in a solution too heavy to be practicable. In these cases, instead of using the specific amounts of powder by weight shown in the above formula, it may be necessary to reduce the quantity of powder with the objective of producing a bale coating solution which will flow on readily and remain bonded to the rubber after drying.

C. Limitation on Use of Bale Coating

After coated bales are dry, the maximum weight of bale coating solids shall not exceed 16 oz. (0.45 kg) per bale (of 0.14m3 in volume) and no bale coating shall appear below the outer wrapper sheet.  

 

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Conformance or Non-Conformance Procedures

1 Milling Test - Physical

Actual dispersing test using sample of bale surfaces covered with the coating in question. Care should be take to select a part of the wrapper sheet that is free from adhering dirt.

(a) Break 400-450 grams of the rubber down on a warm laboratory mill with an opening of 0.055 inches (1.40 mm) at approximately 160F (71C) for 4 minutes.
(b) Cut each way 6 times and sheet rubber off at an approximate thickness of 0.090 inches (2.29 mm).
(c) Examine visually with the naked eye for dispersion of coating material. NOTE: The official coating will be uniformly dispersed and without agglomeration while non-acceptable coatings will show undispersed powders.

2 Tests for Powder, Clay, Whiting and Gypsum

(a) Talc and clay are insoluble in dilute hydrochloric acid.
(b) One may be differentiated from the other by microscopic examination.
(c) Whiting is dissolved by dilute hydrochloric acid, giving off effervescent bubbles.
(d) Calcium sulphate (gypsum) is partially dissolved by dilute hydrochloric acid. Filter off insoluble material and test filtrate with barium chloride solution for sulphates.

3 Starch Test

To determine if starch, tapioca, or flour is used as a binder, scrape off some of the coating material, boil in water, cool and add iodine solution. If any of these are present, a blue color will develop. The iodine test solution can be made by diluting ordinary tincture of iodine with some water.

4 Glue Test

To determine if glue is used as a binder, remove some of the coating, burn and observe the odor. If the odor is that of wool, burnt bone or burnt meat, glue is present.

5 Resin Test

No available test is known as yet.  

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Bale Marketing Requirements

At least the following marks, in addition to those required by law, must appear on each bale:

(a) Grade Marks - On two sides of the bale. Should be eight-inch (20.3cm) characters.
(b) Firm Marks - Letters identifying the shipper's firm on two sides of the bale. Should be fine-inch (12.7 cm) characters.
(c) Lot Identification Marks - Numbers appearing immediately below the firm marks on not less than two sides of the bale. These should be five-inch (12.7 cm) characters. These number must be the same on all bales covered by the same bill of lading. Different numbers must be used for each separate bill of lading covering lots shipped by a single firm and loaded on the same vessel.

(Size of characters here above required are not binding if the buyer's contract authorizes a weight for the bales lower than the minimum weight specified under Sections 1,2,3,4 and 5) These marks must be stenciled on rubber covered bales or on the burlap or rubber patches. No particular bale marking solution or pigment is specified. Bale marking paints developed and manufactured in rubber producing countries and endorsed and accepted by the rubber research institutes of these countries shall be used.
Marking paints used on Pale Crepes, shall not penetrate below the wrapper sheets.

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Lemar International Sdn Bhd (14991-D)
Head Office:
WISMA LEMAR, NO. 2, Jalan BP 4/1,
Bandar Bukit Puchong, 47100 Puchong, Selangor Darul Ehsan. 
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Tel:  (603) 8060-2105
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E-mail:  lemar@lemarrubber.com

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