19.4   Gums & resins
Characteristics and fitness for container transport
Most gums and resins originate in the tropics and are transported to temperate latitudes. Gums and resins are exudates from plants, usually in the form of solidified plant saps, such as asafetida, gutta-percha, gamboge. The hardened, rubbery mucilaginous sap from tropical acacias is known, for example, as gum arabic and balata gum. Gelatinous plant exudates include gum tragacanth, karaya gum. Examples of soft resins or balsams include damar, copal, rosin, Canada balsam. Montan wax is a fossil plant wax. Examples of tanning extracts include catechu black, gambir, quebracho extract, wattle extract, mangrove extract.
Gums and resins vary in color from white to yellow to brown.
Gums and resins are usually produced in the form of granules, roundish pieces (asafetida), often as brittle, crumbly pieces (damar, rosin, Japan wax, montan wax), rarely as powders (quebracho extract, gum arabic) or cast in sheets (shellac, gutta-percha).
Gums, resins and extracts are used as tannins (myrobalan extract, gambir, catechu black, mangrove extract), in medicine (asafetida, gum arabic, damar), pharmaceuticals (gamboge), in the chemicals industry (paraffin, montan wax, rosin), in dyeing (gamboge, myrobalan extract), in adhesive manufacture (gum arabic) and for industrial applications (balata gum for drive belts, gutta-percha for electrical insulation).
Gums and resins contain only a little water and are classed in water content class 1 (WCC 1). Rosin belongs to water content class 0 (WCC 0) because its water content has been removed by steam distillation.
These are goods whose respiration processes are suspended but in which biochemical, microbial and other decomposition processes still proceed; they are thus goods which display 3rd order biotic activity (BA 3).
Gums and resins require particular temperature, humidity/moisture and possibly ventilation conditions (SC VI).
If gums and resins are to be transported in standard containers, they must be container dry when supplied by the manufacturer. Stowage below deck should also be provided in order to avoid solar radiation, especially in the tropics, and the steep temperature gradients on deck. Unfortunately, little or no influence is to be had over container stowage positions on the ship, despite the latest developments in data processing. Ideal conditions would be provided by open-sided containers in well ventilated lower holds (protection from solar radiation and temperature variations), with the option of providing ventilation to prevent the formation of sweat.
Transport instructions and damage
Gums and resins are transported in bags, cases, drums, rolls, bales and cartons on pallets (paraffin). Double-layered bags with a jute outer bag and plastic liner are mainly used (damar, copal).
Gums and resins soften and melt at elevated temperatures.
No. Name Melting temperature
1. Balata gum becomes soft and plastic at 50°C and cakes in temperate latitudes.
2. Benzoic resin melting point at 75°C, sticks to case lumber.
3. Damar melting point at 84°C (hard grades), syrupy liquid at 120°C, soft grades of damar ferment readily.
4. Gambir solid appearance before loading; softens to a slimy mass, then cakes.
5. Gutta-percha begins to soften at 37°C, becomes plastic at 50 - 65°C, melts and breaks down at 120 - 130°C; cakes at low temperatures.
6. Japan wax begins to melt at 50°C.
7. Candles: temperature variations can make candles melt together, making them unsalable.

48 - 50°C
  Paraffin 53 - 54°C, releases oily substances on exposure to heat.
  - Stearin 50 - 54°C
  - Wax 60 - 80°C
8. Rosin softens at 55 - 83°C, melting point 100 - 130°C.
9. Copal rapidly softens, coalesces, ferments and cakes.
10. Montan wax melting point at 80°C
11. Myrobalan extract: tends to soften rapidly.
12. - Paraffin, hard melting temperature at 50 - 60°C
13. - Paraffin, soft melting temperature at 42 - 50°C
14. Quebracho extract when exposed to temperatures > 25°C tends rapidly to form lumps and stick together; cakes at < 5°C.
15. Shellac begins to flow at 40°C, cakes completely;
risk of sheet breakage at 0°C.
16. Wattle extract begins to flow at 18 - 25°C, bags "weep" and then stick together; cakes at < 5°C.

   Table 34: Melting temperatures of gums, resins and extracts [28]
Gums and resins are generally water-soluble. They must be protected from all forms of moisture. Gum arabic, for example, forms a sticky, viscous solution when exposed to moisture, as does catechu black. Some (damar) start to ferment; gamboge dissolves. Copal, especially when fresh, suffers spoilage.
Gums and resins must most particularly not come into contact with seawater as this greatly impairs their subsequent use. Before the container is packed, it must therefore be subjected to a thorough tightness inspection. In order to provide protection from condensation, a nonwoven fabric which can absorb considerable quantities of water may be suspended in a standard container. While this cannot completely eliminate all risk of damage, the goods are at substantially lower risk of wetting. Benzoic resin, gutta-percha, paraffin and shellac are not water-soluble. Rosin is sparingly soluble in water.
Gums, resins and extracts may range from having an extremely strong odor to being virtually odorless. Asafetida or Devil's dung has a penetrating and nauseating odor due to its 6% content of sulfur-containing asafetida oil, an essential oil which smells of garlic. Benzoic resin releases an odor of vanilla or incense; resins primarily cause damage due to their resinous odor; balsam gum releases a turpentine-like odor, while jelutong gum has a rubber-like odor. Paraffin is virtually odorless.
Overall, most gums, resins and extracts cause odor-tainting, which means that containers must always be cleaned after unpacking. On the other hand, many gums, resins and extracts are odor-sensitive, such as gum arabic, benzoic resin, gum tragacanth, karaya gum and paraffin.
Melting, flowing, stickiness due to exposure to heat or moisture may cause staining damage and discoloration. Mangrove extract makes red stains.
These goods are primarily susceptible to contamination by dust. Care must therefore be taken only to accept containers for packing which are absolutely clean.
Toxicity/Hazards to health
Some resins, such as gamboge, are toxic. Due to the benzoic acid esters it releases, benzoic resin is slightly to moderately toxic. Some resins consume oxygen, such as benzoic resin, damar, rosin, copal and shellac.

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