Resin Plant

A varnish is often appHed on top of the paint layers. A varnish serves two purposes as a protective coating and also for an optical effect that enriches the colors of the painting. A traditional varnish consists of a natural plant resin dissolved or fused in a Hquid for appHcation to the surface (see Resins, natural). There are two types of varnish resins hard ones, the most important of which is copal, and soft ones, notably dammar and mastic. The hard resins are fossil, and to convert these to a fluid state, they are fused in oil at high temperature. The soft resins dissolve in organic solvents, eg, turpentine. The natural resin varnishes discolor over time and also become less soluble, making removal in case of failure more difficult (see Paint and FINNISH removers). Thus the use of more stable synthetic resins, such as certain methacrylates and cycHc ketone resins, has become quite common, especially in conservation practice. 

Plant resins, poison ivy, poison oak, poison sumac Metals (nickel or gold in jewelry)... 

Natural resins Pine resins, sandarac, copals, mastic, dammar, amber, frankincense, benzoe, styrax, myrrh, (plant resins) shellac (animal resin) tar and pitch (from thermal treatment of plant resins or wood) Varnishes, coatings, waterproofing materials, paint binders, ingredients of cosmetic and pharmaceutical preparations... 

Plant resins are lipid-soluble mixtures of volatile and nonvolatile terpenoid and/or phenolic secondary compounds that are usually secreted in specialized structures located either internally or on the surface of the plant. Although terpenoid resins constitute the majority of the resins produced and used, some other important resins are phenolic. Phenolic resin components, which occur on the surfaces of plant organs, have been used particularly in medicines [86]. 

Frankincense, also known as olibanum, is obtained from trees belonging to the genus Boswellia (Burseraceae family). It is one of the best-known ancient plant resins. The ancient Egyptians were the first to use it as incense in embalming practices and in the preparation of medicines, cosmetics and perfumes, and today it is still used therapeutically. It contains pentacyclic triterpenoids belonging to oleanane, ursane or lupane type molecules and in particular of a- and p-boswellic acids, and their O-acetates [104 111], 11 -Oxo-p-boswellic acid and its acetyl derivative, identified in several Boswellia species, are also diagnostic for frankincense [112]. 

J.H. Langenheim, Plant Resins, Chemistry, Evolution, Ecology, and Ethnobotany, Timber Press, Portland, 2003. 

Such methods were recently shown to be efficient fingerprinting tools to assess the different kinds of lipid and wax substances present in a sample, as well as some additives, particularly plant resins (see Chapter 3). 

Each painter had his own technique the binding medium was thus prepared using different additives, giving rise to a variety of recipes for each technique. For example, it is believed that fig latex (a white liquid exuded by the fig tree) was commonly added to the egg tempera, and that animal or plant resins were added to oil- and wax-based binders. On account of their adhesive properties, these materials were used not only as paint binders, but also as consolidants in restorations, as ingredients in varnishes used to finish paintings, and as ingredients of mordants to apply metallic leaf decorations. 

Plant resins are discussed in detail in Chapter 12. Since plant resins were once common additives for paint binders, this section briefly reviews the literature, focusing on the use of different derivatising agents. 

Fresh plant resins have been characterised by means of pyrolysis coupled to GC/MS without the use of a derivatising agent. However, many markers used for the identification of resins in samples from works of art are often not cogent, and moreover they disappear during ageing [42]. 

Aside from the characterization of birch bark tar, higher plant resins and their heated derivatives and beeswax, what potential remains for the identification of other organic substances used in prehistoric Europe This short summary intends to whet the appetite by briefly reviewing recent investigations and... 

Thomas BR, Modern and fossil plant resins, in Harborne JB (ed.), Phytochemical Phylogeny, Academic Press, London, pp. 59—79, 1970. 

Dyestuffs of plant origin include indigo blue, used to dye jeans. A poison of detective novel fame is strychnine, obtained from the plant resin curare (Box 1.6). 

Ophiorrhiza japonica Blume 0. mungos L. Japan She Gen Cao She Gen Cao (whole plant) Resin, alkaloid, beta-sitosterol, 5 alpha-ergost-en-3 beta-ol, 5 alpha-ergost-8(-14)-en-3B-ol, tannates, hydrogen cyanide.50 For circulatory and pulmonary ailments. 

Regarding the question of the presence of isopropyl groups in coal, we do not think this point has been proved beyond doubt because (1) the content found by Heredy et al. was hardly 0.4% of coal, and (2) the low rank bituminous coal they studied may well have contained significant proportions of foreign inclusions like plant resins. The isopropyl groups identified by the authors may be structural parts of such resins (abietic) rather than of the real matrix of coal structure. 

Usually diterpenes are found in plant resins and latexes where they are involved in their sticky texture. Resins often exude from the wounds of a... 

Figure 8.14 Flow diagram showing the use of hydrocarbon-permeable membranes to recover unreacted monomers from a polyolefin plant resin degassing unit. The photograph is of a system installed by MTR in Qatar in 2007.

Amber is the fossilized resin (sap) from plants. Fossilization occurs when a specimen of plant resin is buried and gradually becomes compressed and partially dehydrated. Partially fossilized resin is called copal, which is less dense and softer than true amber. 

Modem plant resins are often substituted for true amber, and it is often difficult to tell the difference. Some trees and shmbs will produce copious amounts of resin if wounded, so people will purposefully cut into the outside of a plant. Kauri gum is probably the most common resin collected this way. When the... 

Amber can be found in rocks dating back to the Mesozoic era, about 80 million years ago. There undoubtedly were deposits of plant resin before that time, but they have failed to survive to this day. This may be due to the gradual breakdown of the hydrocarbons that constitute most amber, as well as its dehydration after burial. 

Bark of birch and other trees has been used to make canoes and shallow-draft boats in many parts of the world. Large pieces of bark are usually stretched over a wooden framework, and the seams are sealed with plant resin or pitch. 

Plant resins and distillates from a wide variety of plants have been used as coatings and to impregnate porous materials. The purpose of these activities was usually to provide an object or material with water resistance and, sometimes, added strength. 

When turpentine has been distilled from plant resin, the remaining residue is rosin, which is used to increase surface friction. Rosin may also be derived directly from plants, if the natural resin is dehydrated. The common uses of rosin are in soldering flux, and as a surface treatment on stringed musical instruments. Athletes also use rosin to enhance the grip of hands and feet in many fields, from gymnastics to ballet. 

In order to produce harder, tougher materials, inventors combined plant resins with other plant and animal fluids, and inorganic materials such as diatomaceous earth, and pulverized glass, porcelain, or stone. The resultant compositions could take much more abuse than earlier molded resin compounds, and were made into everything from door knobs to billiard balls. 

Perfume is the most concentrated form of a liquid scent. Toilet water and cologne are dilute variations. Potpourri is a mixture of naturally-scented plant parts, usually flower petals, seeds, leaves, and bark. Incense is a substance that gives off a scent when heated. These are usually plant resins, either used in their natural state or combined with other substances to increase or change the smell. 

Terpenes are volatile constituents of plant resins and essential oils... 

Pitch is the residue after the distillation of volatile resin components in an open vessel. The material is typically black and is referred to as pix by Roman writers (I). When obtained from pine resin, it may be called pine pitch when obtained from other plant resins, it may be called more generally wood pitch. 

The distillate of resin distillation is called tar. Pine tar is from pine resin, and wood tar is from other plant resins. Coal tar is made from coal. The use of tar in antiquity is uncertain and unlikely (2). 

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