Natural resin
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Description
A class of solid materials obtained from excretions from certain trees or shrubs. Sometimes incisions are made in the trees to encourage resin flow. Natural resins are aromatic hydrocarbons that are generally soluble in alcohol or turpentine and insoluble in water. They are clear to translucent thermoplastic resins with a yellow to brown color. Most break with a conchoidal fracture and burn with a sooty flame. Resins are used as varnishes, adhesives, inks and additives in paint media. Common examples are: Rosin, Amber, Copal, Dammar, Kauri, Balsam, Mastic, and Sandarac.
Properties for Common Natural Resins
| Resin | Source/type | Melting point (°C) | Density | Ref. Index | Acid number | Saponification number | Solubility | Characteristics | Uses |
|---|---|---|---|---|---|---|---|---|---|
| amber | fossil resins | 250-325 | 1.05-1.1 | 1.54 - 1.55 | 15-35 | 115-225 | Amber is very resistant to acids and alkalis and is not entirely soluble in any solvent | yellowish, hard, glassy, fossil resin; Mohs hardness = 2.5- 3.0; Succinites emit succinic acid when heated; fluoresces a strong yellowish green to bluish white in short-wave UV light | carved for jewelry, beads, amulets, and small vessels; used as an ingredient in paint and oil/amber varnishes are made by dissolving melted amber in amber oil, turpentine oil, or a drying oil. |
| copal | diterpenoid resins from Trachylobium species (Africa), Hymenaea courbaril (South America) and Agathis australis (New Zealand). | 180-340 | 1.04-1.13 | 1.528- 1.545 |
122-128 | 132-178 | After melting, copals are soluble in oil and turpentine. Soft copals are partially soluble in ethanol, chloroform, glacial acetic acid. | May fluoresce white in short- wave UV | varnishes for coaches, linoleum, oilcloth, amber subsitute |
| dammar | triterpenoid resin from Dipterocarpaceae trees in southeast Asia of the genera Shorea, Balanocarpus, or Hopea | 90 (softens); 100-180 (melts); Tg =39.3 |
1.04-1.12 | 1.515 - 1.539 |
16-18 | 20-65 | Soluble in turpentine, oil, chloroform and aromatic hydrocarbons | Darkens with age. Turns cloudy when moisture is present during preparation | picture varnish, printing ink, mounting thin sections, alkyd baking enamels, paper and textile coatings |
| elemi | from trees of the family Burseraceae | 77-121 | 17.8-25 | 25-50 | Soluble in ethanol, ether, chloroform, benzene. Insoluble in water, turpentine and mineral spirits. |
Soft,sticky, odoriferous resin | plasticizing additive in varnishes; lithographic inks, paper and textile coatings, perfume bases, waterproofing | ||
| mastic | triterpenoid resin from mastic shrub, Pistacia lentiscus, in southern Europe and northern Africa | 95-120; Tg =34.7 |
1.074 | 1.535- 1.536 |
50-71 | 82-92 | Soluble in oil, turpentine, ethanol, diethyl ether, benzene, acetone, chloroform | Darkens and become less soluble with age. May turn cloudy if moisture is present during preparation. | picture varnish, additive in oil media; printing ink, chewing gum |
| rosin | oleoresinous exudate from Coniferae trees (longleaf pine (Pinus palustris), Cuban pine (P. caribaea), loblolly pine (P. taeda), cluster pine (P. pinaster), or Scotch pine (P. sylvestris)) | 100-150 | 1.07-1.10 | 1.525- 1.548 |
150-180 | 150-200 | Soluble in ethanol, acetone, turpentine, acetic acid, carbon disulfide | Oxidizes easily and may blacken with age. Combustible, burning with a yellow, sooty flame. |
paints, varnishes, inks, adhesives, sealing wax, soldering fluxes, and linoleum. Also used to increase sliding friction on musical instrument bows and dance floors |
| sandarac | from the alerce tree Callitris quadrivalvis native to Australia and the sandarac tree Tetraclinis articulata native to northern Africa | 135-150 | 1.078- 1.088 |
1.545 | 140-155 | 143 | Soluble in ethanol, ether, acetone, amyl alcohol and hot alkali. | Brittle | spirit and oil varnishes |
| shellac | excreted by the female of the lac insect, Laccifer lacca, native to India | 115-120 | 1.035- 1.140 |
1.516 | 48-64 | 185-213 | Fresh shellac is soluble in ethanol, acetone. Shellac becomes insoluble with age | Iodine number = 10-18; unbleached shellac will autofluoresce orange; moisture can produce a white haze on dried surface |
furniture polishes, protective coating for plaster molds, composition products; gramophone records |
Synonyms and Related Terms
resina natural (Esp.); résine naturelle (Fr.); resina naturale (It)
Physical and Chemical Properties
- Optically darken with age
- Many autofluoresce when aged.
- May be soluble in alcohols, turpentine, carbon disulfide. Insoluble in water.
For easy printing and to download
Resources and Citations
- Wikipedia: Resin Accessed October 2024
- R. J. Gettens and G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966.
- Thomas Gregory, The Condensed Chemical Dictionary, Reinhold Publishing, New York, 3rd ed., 1942
- ASTM, "Standard Terminology Relating to Paint, Varnish, Lacquer and Related Products", Annual Book of ASTM Standards, Section 6, Paints, Related Coatings and Aromatics, ASTM, D16, 7-Jan, Jul-96
- Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- John S. Mills, Raymond White, The Organic Chemistry of Museum Objects, Butterworth Heineman, London, 2nd ed., 1994
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998