Lead soap

In modem manufacturing methods the oil is sometimes reacted directly with the glycerol to form a monoglyceride and this is then reacted with the acid to form the alkyd resin. When the resulting surface coating is applied to the substrate the molecules are substantially linear. However, in the presence of certain driers such as lead soaps there is oxidative cross-linking via the unsaturated group in the side chain and the resin hardens. 

In order to obtain information regarding the composition of these degradation products, aqueous extracts of the lead soaps of the linseed oil fatty acids were analysed, mainly by chromatography. The extracts contained formic acid 46%, azelaic acid 9% and pelargonic acid and its derivatives 27%, the remaining 18% consisting of a mixture of acetic, propionic, butyric, suberic, pimelic and adipic acids. It was shown that whereas the salts of formic acid were corrosive, those of azelaic and pelargonic acid were very efficient inhibitors. 

In positive ion mode, the characteristic peaks representative of the binding media were fatty acids from lead soaps (of palmitic acid at m/z 461 463 and of stearic acid at m/z 489 491). Other peaks corresponding to mono- and diacylglycerol cations, protonated stearic acid or its acylium ions could be found in the spectra of the reference products but not in the paint sample. The spectrum of lead white egg tempera paint exhibits peaks of phosphocholine (m/z 184) and protonated ketocholesterol (m/z 401). These peaks were not found in the spectrum from the cross-section. In negative ion mode, the spectrum of the oil... 

Figure 15.11 Cross section of a sample from a painting from the Hudson River School presenting a round protruding mass, (a) SEM image and EDX images of (b) lead, (c) lead soaps, (d) azelaic acid and (e) stearic acid. Reprinted from Boon et ah, Microscopy and Microanalysis, 11, Supplement 2, pp. 444 445, 2005, by permission of Cambridge University Press (see colour Plate 6)...

J. J. Boon, K. Keune and J. Zucker, Imaging analytical studies of lead soaps aggregating in preprimed canvas used by the Hudson River School painter F. E. Church, Microscopy and Microanalysis, ll(Suppl. 2), 444 445 (2005). 

Lead monoxide has wide commercial apphcations. It is used in lead-sulfuric acid type storage battery plates in optical and electrical glasses in vitreous enamels, glazes, and fine tableware in lead soaps for varnishes as a vul-... 

The remedy is the substitution of soap, which, by its slight excess of alkali, rendering soluble in and miscible with water all the dirty grease of the clothos and oily sxudations from the pores of the skin, is at the same time detersive Itself for, though composed of oil and alkali in a state of combination, it still possesses the influence of the lattar without any of its hurtfulness. Oleate of oxide of lead, formerly called lead soap, is insoluble, and constitutes the diachylon plaster of pharmacy. The analogous salts of zinc and lime, formerly termed zinc soap and lime soap, are also insoluble. 

The electrochemical action of red lead results from the fact that lead has valencies of 2 and 4 in lead orthoplumbate Pb(IV) compounds are reduced to Pb(II) in the cathodic region [5.147]. The chemical anticorrosive effect is a result of lead soaps that are formed when fatty acids in the binder react with the red lead. The lead soaps permeate the paint film as lamellae, and give good mechanical strength, water resistance, and adhesion to the steel surface. Furthermore, the corrosion-promoting chloride and sulfate ions are precipitated by lead(II) ions [5.148]. 

HCOO)2Pb + H2S = PbS + 2H.COOH Lead monoxide, like silver oxide, may be used in the presence of water, for hydrolysis. Fats, for example, are saponified (hydrolysed) by boiling them with water containing PbO in suspension the resulting products are glycerol and a lead soap ... 

Lead compounds, usually based on a mixture of lead salts, e.g., tribasic lead sulfate or dibasic lead phosphite, and lead soaps, e.g., dibasic or normal lead stearates, have been very cost effective heat stabilisers for many years, and function as HC1 absorbers (236, 365,438). 

White Castile soap—Sax>o (U. S.), Sapo durus (Br.)—is a Xa soap made from olive-oil strongly alkaline, hard, not greasy, very soluble contains 21 per cent. HjO. Sapo mollis (Br.) is a K soap made from olive-oil, and contains an excess of alkali and glycerol. TeUow soap is made from tallow or other animal fat, and contains about i its weight of rosin. Emplastrum plumbi (T7. S., Br.) is a lead soap, prepared by saponifying olive-oil with litharge. 

NIOSH considers Lead to mean metallic lead, lead oxides, and lead salts (including organic salts such as lead soaps but excluding lead arsenate). The NIOSH REL for lead (8-hour TWA) is 0.050 mg/m air concentrations should be maintained so that worker blood lead remains less than 0.060 mg Pb/100 g of whole blood. 

Langmuir-Blodgett pseudocrystals. These are usually fabricated from the lead soap compounds (e.g., lead stearate) and are made by coating alternate layers of lead stearate molecules onto a suitable... 

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