In Greece it is masticated (hence its name) as a kind of chewing gum. Mastic has been used in crafts since antiquity. They all have relatively high refractive indices. LMW resins have relatively high glass transition temperatures and are generally brittle.
As LMW resins oxidize, an increase in the molecular weight may occur, but this molecular weight will still be considerably lower than the starting molecular weight of a polymer and the resins will remain soluble as they age ( Maines, personal communication, 1997). Of the LMW resins, the solubility of natural resins and ketones will change the most over the long term both requiring increasingly polar solvents for removal. Some LMW resins are more glossy than others, but they all dry in a glossy film compared to polymers.Īll LMW resins used for picture varnishes are initially soluble in a solvent less polar than xylene (of the resins in this section mastic requires the strongest solvent). Therefore, they saturate better than polymers. LMW resins level well because they make solutions of low viscosity even at high concentrations and will continue to level when they are applied to artworks and dry to a smooth and glossy film. The smaller molecule size has a significant effect on the visual appearance and physical properties of these resins. Although the class of LMW resins includes materials that are chemically different (e.g., mastic, damar, Laropal® K80, MS2A®, Regalrez® 1094, and Arkon® P-90 are all LMW resins), they share certain common characteristics. LMW resins are a group of resins consisting of small molecules with average molecular weights of 500–1000 ( de la Rie 1987, 4). The characteristics of low molecular weight (LMW) resins are determined by differences in molecular weight. Introduction: General Characteristics of Low Molecular Weight Resins for Picture Varnish 6.1.5 Working Characteristics and Practical Properties.6.1 UVS (Ultraviolet Stabilized) Finishing and Matte Varnishes.6 Proprietary Varnishes Based on Recently Introduced Low Molecular Weight Resin Varnishes.5.3.5 Working Characteristics and Practical Properties.5.2.5 Working Characteristics and Practical Properties.5.1.5 Working Characteristics and Practical Properties.5 Recently Introduced Low Molecular Weight Resin Varnishes.4.2.5 Working Characteristics and Practical Properties.4.2 Talens Picture Varnish® (formerly Rembrandt®).4.1.5 Working Characteristics and Practical Properties.4.1 Artists' Gloss Varnish® (formerly Winton®).4 Proprietary Varnishes Based on Ketone Resins.