Varnish,defined

Concentration of Electrolyte Myer and Sievers"" applied the Donnan equilibrium to charged membranes and developed a quantitative theory of membrane selectivity. They expressed this selectivity in terms of a selectivity constant, which they defined as the concentration of fixed ions attached to the polymer network. They determined the selectivity constant of a number of membranes by the measurement of diffusion potentials. Nasini etal and Kumins"" extended the measurements to paint and varnish films. 

To be suitable for use in museum preservation and restoration practice, picture varnishes must have a number of defined characteristics (a) they must not interact with the object in a detri-... 

I had three purposes in presenting these remarks. The first was to call attention to the fact that in the course of thermally and photochemically activated deterioration, organic materials such as paper, paints and varnishes, textiles, and adhesives tend to react with oxygen in a reasonably well defined series of stages. This concept provides a guide for analyzing and investigating deterioration problems further (32). 

There is an extraordinary body of terms used to define various features of protective coatings. Before discussing paints and varnishes and the particular function of fats and oils in coatings, it is desirable to review and define some of the language of the industry. 

Thebainone-B [xm] is best prepared as its hydrobromide by the hydrolysis of dihydrothebaine- [iv] with alcoholic hydrobromic acid [13], but it is also formed by the hydrolysis of the same base with mineral acid in aqueous solution [13], a reaction first reported to give an ill-defined substance, isocodeine [18], and later said to give a coloured, varnish-like substance [3]. Thebainone-B appears to be stable only as its salts in the dry state, the damp salts and free base readily degenerating to brown tars [13]. The ultra-violet spectra of thebainone-A, /3-thebainone-A, and thebainone-B closely resemble those of dihydrothebaine- and codeine, whilst that of thebainone-C is widely different (Fig. 8) and the frequencies of the carbonyl-absorption in the infra-red indicate that whereas thebainone-A and /3-thebainone-A are a /3-unsaturated ketones, the unsaturation is /3 y- in thebainone-B and thebainone-C [13]. On this evidence thebainone-B is allotted the structure [xm]. It can be catalytically reduced to dihydrothebainone [ix], in which the configuration at C-14 is the same as in codeine [13] (cf. the production of dihydrocodeine on reduction of neopine [xiv] [19]). 

Ligrotn, V.M. P. naphtha varnish makers and painters naphtha refined solvent naphtha solvent naphtha Benzoline Canadol. Term rhat has been applied to petroleum fractions of the same nature as described for petroleum benzin, q.v.. but of higher density, higher boiling range and higher flash pr. Defined by ASTM prior to 1950 as synonymous with petroleum benzin and petroleum ether ASTM standard specification D 288-49, 865-867 (1949),... 

Novolacs are solid at normal temperature and generally have a well-defined melting point. The largely inert behaviour of novolacs means that they can only be used for physically drying paints and coatings. They are extremely good soluble in polar solvents such as alcohols, ketones, and esters, but are insoluble in aromatic and aliphatic hydrocarbons (e.g., xylene, benzene). Spirit varnishes are novolacs dissolved in alcohol that are primarily used as unpigmented varnishes they have an... 

Solvents are normally defined as fluids having a maximum b.p. of250 C, which are able to dissolve other components of paints, especially binders. They evaporate under drying conditions when paint films are formed.Solvents must not react with the painted or varnished product. 

Test chamber (volume 1 m, defined conditions temperature, humidity, air changing rates, air velocity). This is usually carried out 3 days after application of paints or varnishes by placing the products into a test chamber. The test series starts with sampling emissions of the products on defined absorption materials (Tenax, charcoal filters, activated charcoal), reconditioning and finally identification and classification of VOCs with gas chromatography. The test methods are repeated after 14 and 28 days. These test criteria permit determination of the behavior of emissions from finished products under defined conditions. 

Coat n. Paint, varnish or lacxjuer applied to a surface in a single application (one layer) to form a properly distributed film when dry. A coating system sexually consists of a number of coats separately apphed in a predetermined order at suitable intervals to allow for drying or curing. It is possible with certain types of material to build up coating systems of adequate thickness and opacity by a more or less continuous process of application, e.g., wet-on-wet spraying. In this case, no part o the system can be defined as a separate coat in the above sense. 

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