Siccative oils

The proteinaceous binders are one of the main constituents of the wide range of organic materials and are a central component of the artist s palette. In the technique referred to as tempera, artists commonly used proteinaceous binders derived from egg, milk or casein, and collagen glues derived from animal skins or bones. These can be used independently, mixed together, or in a more complex mixture with siccative oils (as in the tempera grassa technique) or plant gums. 

A. Piccirillo, D. Scalarone and O. Chiantore, Comparison between off line and on line deriva tisation methods in the characterisation of siccative oils in paint media, J. Anal. Appl. Pyrol., 74, 33 38 (2005). 

S. Prati, S. Smith and G. Chiavari, Characterization of siccative oils, resins and pigments in art works by thermochemolysis coupled to thermal desorption and pyrolysis GC and GC/MS, Chromatographia, 59, 227 231 (2004). 

Spatially resolved MS techniques that make use of ionic sources based on direct LDI have been employed to study art and archaeological objects since 2002 [43,44]. However, direct LDI is only effective in the study of a limited range of materials. TTie use of matrices that assist the ionization process induced by MALDI has expanded the applicability of LDI-based MS methods to the field of spatially resolved studies of organic components from works of art. Examples of the applicability of MALDI to the analysis of pigments [45], siccative oils [46], proteinaceous binders [47-49], and varnishes [50] are indeed reported in the literature. A proteomic approach based on the use of MALDI-TOF was also used to identify biological samples taken from the more than 5300-year-old Tyrolean mummy, also called iceman or Oetzi [51]. 

So-caUed siccative oils such as linseed oil and hemp oil (generally not food-compatible), are transformed into resins under the influence of the oxygen contained in air. They are used for the preparation of varnish, paints, etc. 

Metallic compositions serving as siccatives catalyze the well-known oxidation and polymerization of oil in paints and other finishes. Likewise, ferrous and other metallic objects boost self-heating in piles of lignocellulosics. Among the known catalyzing substances are iron sulphides and iron oxides from combustion gases of... 

Binoxide of menganese has been employed for increasing tho siccative quality of linseed oil and the artificial binoxids, mixed with the same oil, has been... 

Use Paint and varnish drier and bodying agent, detergent in lube oils, the solution in organic solvents has been proposed for insecticides and siccatives. 

The precipitation of soaps by polyvalent ions in aqueous solutions is considered to be troublesome in many applications. However, because metal soaps are soluble in organic solvents, mineral oils and fats, they are valuable additives in the production of plastics where they are used as mould-separation agents, emulsifiers and stabilizers. The fatty acid salts of lead and cobalt are used as siccatives in varnish and paints. 

Oil paints solvent-lfee No. 665 standard oils, calcium carbonate, pigments, siccatives, lemon oil water-soluble exterior coating (paneling)... 

Siccatives n. Any reagent which catalyzes or promotes oxidation of oils a drier. 

The C=C unsaturation in all these structures is 1,2-disubstituted, so initiation and propagation by free-radical and cationic mechanisms are sluggish. Hence, they elicit slow processes and poor yields of macromolecular structures though, ultimately, crosslinked materials are generated (as in the case of classical oxido-polymerisation discussed in Chapter 2). Preparation of blown oils by thermal treatment >300 C is also a poor approach because of substantial losses associated with thermal degradation. It follows that applications are not particularly attractive in practical terms except in the traditional realm of siccative paints and inks. 

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