Soft resins

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. 

Mastic. Most commercial mastic [61789-92-2] is collected on the Greek island of Chios, near the Turkish coast. It is a soft resin with a softening point of 55°C. It has an acid number of 50—70 and a saponification number of 62—90. It is soluble in alcohols and aryl hydrocarbons. Mastic is used in wood coatings, lacquers, adhesives, and printing inks. 

Shellac is a complex mixture made of mono- and polyesters of hydroxy-aliphatic and sesquiterpene acids, which can be separated into two fractions the soft resin, soluble in ether, mainly consisting of monoesters [134], constituting about 30% of the total resin and the hard resin, ether insoluble, which has quite a complex polyester composition, and... 

In the nineteenth century dammar, a soft resin derived from trees of southern Asia was introduced in Europe and used for making colourless varnish. Mixed with oil of turpentine it has become the preferred varnish for oil painting, due to its superior optical properties and better ageing stability than the other natural resins. 

A different reason for appropriating a material object comes from the kauri (Agathis alba) and merkus (Pinus merkusii) pine forests of Malaysia. Local people collect soft resin from these trees and sell it as a cash crop. Under the name Malay damar, this exudate is exported as a valued ingredient for high quality varnishes. 

Thorn, L. Patented in Engl In 1890 an expl prepd by treating a mixt of 2p nitrocresol and 1 p Ba or Sr nitrate with a soln of a soft resin (wax, etc) to obtain a plastic mass. This was followed by graining and drying... 

The polyvinylethers form a further group of thermoplastics which are not used as containers or packaging films. They are atactic polymers forming oils, sticky soft resins or nonsticky rubber elastic materials according to their molecular weight and composition. All polyvinylethers are very resistant to saponification by dilute acids and alkalis. They can subsequently be used as unsaponifiable polymer plasticizers and for the manufacture of glues. 

Medium molar mass polyisobutenes are obtained by using higher purity isobutene, by lowering the temperature to — -25 to -40° C, and eventually by operating in the presence of a chain-terminating agent (diisobutenes) [12]. The semiliquid or soft-resin polymers present typical Mv in the range 40-85 103 (M = 8-13-103). 

The lipophilic soft resin consists of a series of phloroglucinol derivatives known as a-ac-ids (humulone) and )3-acids (lupulone). Both a- and )3-acids are gradnally denatured during storage. The hard resin contains both a hydrophilic fraction (5-resin) and a lipophilic fraction (/ resin). 

Procter s AlcohoHc Extract of Arnica. Take arnica flowers, 12 oances, troy alcohol, 3 pints water, 1 pint. Mix the alcohol and water, and pour 2 pints of tho mixture over the arnica, previously finely bruised. Allow it to stand for 48 hours, pack it firmly in a percolator, and pour on the remainder of the mixture until 3 pints are obtained. Evapo te this tincture in a water-bath (or still) till reduced to a soft resinous extract. 

Lutonal . [BASF AG] Polyvinyl ethers soft resin for paint, ink, aiteesive industries tackifying resin. 

It has been mentioned previously that cohesive fracture occurred when a soft resin was used as the matrix of such dismantlable adhesives [5]. However, with... 

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