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Modern Paints--Tom Learner
Pages 137-151

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From page 137... ... However, throughout the twentieth century a wide and varied range of synthetic polymers have been developed, many of which have been used as binding media in modern paints. The introduction of these synthetic binders, most notably acrylic, alkyd, and polyvinyl acetate, has undoubtedly enabled great advances to be made in paint technology, in terms of reduced yellowing, greater flexibility, faster drying times, and in the case of emulsion formulations, the elimination of organic solvents as thinners and diluents. Read the entire page →
From page 138... ... and Fourier transform infrared spectroscopy (FTIR) -- are now routinely used at Tate to identify and characterize modern paints from works of art. Read the entire page →
From page 139... ... Alkyd resins are produced from three main components: a polyhydric alcohol, a polybasic carboxylic acid, and a source of monobasic fatty acid, which is often added in the form of a drying oil. The polyhydric alcohol (also called "polyol") Read the entire page →
From page 140... ... . Another technique frequently adopted for the analysis of traditional binding media is Fourier transform infrared spectroscopy (FTIR) Read the entire page →
From page 141... ... -- the acrylic binder used in acrylic solution paints -- with the mass spectrum of the single peak identified as nBMA. The two most intense ions in the mass spectrum are those of m/z = 69 (loss of the n-butoxy side group) Read the entire page →
From page 142... ... Also shown in the pyrogram of Plextol B-500 is the mass spectrum from the most intense peak, MMA. The mass spectrum of MMA shows a similar fragmentation pattern to nBMA seen with acrylic solution paints, with Plextol MMA B-500 (Rohm) Read the entire page →
From page 143... ... is clearly visible. Figure 4 shows a detail from the early part of both of these pyrograms with the mass spectrum of the EA and nBA monomers shown, respectively. Read the entire page →
From page 144... ... The mass spectrum on the right is from palmitic acid (with a molecular ion clearly visible at m/z = 256) , normally the most intense fatty acid observed from a dried oil component. Read the entire page →
From page 145... ... acetic acid + benzene VeoVa DBP phthalic anhydride palmitic acid FIGURE 5 Top: Pyrogram of Emultex VV536, a PVA emulsion with mass spectrum of ethanoic acid/benzene (left) and dibutylphthalate plasticizer (right) Read the entire page →
From page 146... ... The diamond cell simply compresses the sample to a sufficiently reduced thickness for reliable transmission spectra to be obtained. Use of a diamond cell can be problematic with hard and brittle materials, but fortunately the majority of twentieth-century paints are fairly soft materials, which permit easy compression in the cell. Read the entire page →
From page 147... ... The pink curve is the overall spectrum, obtained from an acrylic emulsion paint: FIGURE 7 Overall FTIR spectrum of Hyplar Hansa yellow medium acrylic emulsion paint (Grumbacher 1994 range) (pink line) Read the entire page →
From page 148... ... In this example the PEG has gathered at the upper surface of the paint film, a phenomenon that could have significant ramifications for a painting's appearance and its change with age and/or cleaning. CONCLUSIONS AND LOOKING AHEAD It is possible to identify, characterize, and differentiate the principal classes of synthetic binders used in modern paints with a combination of pyrolysis-gas chromatography-mass spectrometry (PyGCMS) Read the entire page →
From page 149... ... . However, there still remain a great many analytical needs for modern paints, including � improved quantitative methods of medium analysis; � analytical techniques for organic pigments and the additives added to paint formulations; � surface analysis methods for chemical, physical, and optical changes on aging and conservation treatments; and � high spatial resolution techniques to analyze individual layers from layered paint structures. Read the entire page →
From page 150... ... Journal of Analytical and Applied Pyrolysis 8:503-514. APPENDIX EXPERIMENTAL CONDITIONS Pyrolysis-Gas Chromatography-Mass Spectrometry FOM-4LX Curie point pyrolysis unit mounted directly onto the injection port of a Hewlett-Packard 5890 gas chromatograph and interfaced to a Finnigan MAT Incos 50 quadrupole mass spectrometer. Read the entire page →
From page 151... ... ATR work carried out on a Nicolet Magna IR 560 instrument and Nicolet Nic Plan IR microscope with a Spectra-Tech ATR objective with zinc selenide crystal and purged with dry air. Two hundred scans were averaged at 4 cm�1 resolution. Read the entire page →

From page 137...

... However, throughout the twentieth century a wide and varied range of synthetic polymers have been developed, many of which have been used as binding media in modern paints. The introduction of these synthetic binders, most notably acrylic, alkyd, and polyvinyl acetate, has undoubtedly enabled great advances to be made in paint technology, in terms of reduced yellowing, greater flexibility, faster drying times, and in the case of emulsion formulations, the elimination of organic solvents as thinners and diluents.

Modern Paints--Tom Learner Pages 137-151

Modern Paints--Tom Learner
Pages 137-151