The effect of heat on the resistance of varnish.

Varnish and its use has been known since ancient times. Altho the knowledge of varnish has been attributed to the Japanese as early as 500-600 B.C., Tschirsch and A.D. Stevens say that the Japs did not possess this art originally, but that they probably acquired it from the continent during the third century. Nevertheless, varnish did not come into general use until the middle ages. In the 12th century, a monk by the name of Theophilus published the first directions for making an oil varnish, but it was not until 1790 in England, and between 1820 and 1830 in France and Germany, that a factory was established for the commercial production of varnish. In general, a varnish may be defied as a homogeneous, sticky, viscous solution of resins, of a colloidal nature, which when applied to a surface in a thin coat, dries to a hard, smooth, glossy surface. The color of varnish varies considerably, depending on the grade and on its use. Pale varnishes are generally sought, yet there are many dark varnishes of excellent quality. The following scale gives an idea of the degree of color of varnish. A solution of 0.25g K2Cr2O7 in 100g pure concentrated H2SO4 is equivalent to a very light varnish. A solution of 2.00g K2Cr2O7 in 100g pure concentrated H2SO4 is equivalent to a medium varnish. A solution of 4.00g K2Cr2O7 in 100g pure concentrated H2SO4 is equivalent to a dark varnish. Varnishes may be divided into two main classes, according to the manner in which the film dries. The varnishes of the first class, which is the largest and most important, are known as oil varnishes. These varnishes dry mainly by the oxidation of the oil, which forms a tough, elastic film. The secondary drying in these oil varnishes is caused by the evaporation of the volatile vehicle, and by the polymerization of the constituents. On the whole, the drying of an oil varnish is of a chemical nature. The varnishes of the second class are called spirit varnishes. These dry merely by the evaporation of the solvent, and there is practically no chemical action. The gum is transferred from a lump form into a thin sheet by means of the solvent. The most important example of this class is shellac, which is the hardened secretion of the lac insect, dissolved in alcohol

Health Hazards Manual for Custodians, Janitors and Housekeepers

[Excerpt] We will look at the principal occupational health hazards and exposures themselves and some of the related issues. We will look closely at the chemical composition of cleaning products to see what components appear to be particularly hazardous, how you are exposed to them, and what you can do to minimize exposure

Regulation of chemicals : product and process technology as a determinant of the compliance response.

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Chemical Engineering.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.Bibliography: leaves 123-126.M.S

Alligatoring: An investigation into paint failure and loss of image integrity in 19th century oil paintings

"Alligatoring" or "Bitumen cracking" are terms used to describe extreme paint defects found in 19th century oil paintings. This paint failure in the form of severely disfiguring cracking and surface distor- tions often results in a loss of image integrity. This problem has been associated with the use of as- phalt/bitumen paint, with no clear understanding of the materials and mechanisms which contribute to the phenomenon. This thesis investigates this phenomenon from a multi-disciplinary approach that aims to con- tribute knowledge to the study of oil painting suffering from alligatoring. Part 1 focuses on the perception of the problem through a literature survey, and introduces the 19th century painting used in the case study. A thorough review of the literature showed the existing bias created by the perceived connection between appearance and cause, resulting in an association of paint film defects in brown paint with the use of asphalt/bitumen. Because of this, the overall focus of previous research has been the detection of asphalt, considering it in isolation and as the primary factor in the paint defect. This singular view has had significant implications in the study and analyses of paintings with alligatoring. It inhibited wider investigations and overlooked other materials present in the paintings that may be acting in combination or be more predominant in the deterioration mech- anism. The visual and chemical study of the oil painting O Cardeal D. Henrique recebendo a notícia da morte de D. Sebastião, by Marciano Henriques da Silva (1831-1873), painted in Rome in 1861, which exibits extreme alligatoring, offered specific challenges due to its complex and highly disrupted paint layer stratigraphy coupled with the uncertainty introduced by analytical detection limits. For that rea- son, a multi-analytical approach was carried out using Optical Microscopy, micro Raman Spectroscopy, Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometry, X-ray Fluorescence, micro Fourier Transform Infrared Spectroscopy, Fourier Transform Raman Spectroscopy, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy Microscopy, Pyrolysis-Tetramethylammonium Hy- droxide-Gas Chromatography/Mass Spectrometry and Time-of-Flight Secondary Ion Mass Spectrome- try. This research indicates that the deterioration of the painting might be related to the oil binder which has a high degree of oxidation, rich in polar fatty acids and diacids, combined with a lack of the xiv pigments that are capable of stabilizing the paint. The presence of the translucent lead azelate layer above the ground underlines the complexity of the paint layering, materials present, and possible mechanisms for degradation. Part 2 reports on new research carried out using the British colourman Winsor & Newton's 19th- century Archive Database to analyse their production records for “Bitumen” brown for oil tube paints. While there are a substantial number of published recipes in 19th century artist’s manuals for the use of asphalt/bitumen brown, for the first time W&N’s records offer a unique source of detailed infor- mation on the commercially prepared product which differs substantially in ingredients used and method of preparation. The critical analysis of W&N's production records for "Bitumen" revealed that their formulation became standardised in the 1850s and that their product was prepared in two sep- arate steps at two separate locations. Despite standarisation of the ingredients this research revealed that the company still found it necessary to make adjustments for each production run in order to achieve a uniform product. A production record from 1858 was selected and reconstructed, using where possible, histori- cally appropriate materials. W&N’s formulation for bitumen brown oil paint involved a complex mix- ture of ingredients, some of which were other proprietary products sold by the company (these were reconstructed individually using their production records and included drying oil, double mastic var- nish, lead acetate, purple lake and the gelled painter's Medium, megilp). The reconstructions were analysed using thermally assisted methylation with tetrame- thylammonium hydroxide, and pyrolysis comprehensive two-dimensional gas chromatography and compared with the starting material, Trinidad Lake asphalt, to determine how detectable this asphalt is after heat processing in lead treated linseed oil. Results show that asphalt markers identified in the Trinidad Lake asphalt disappear in the first stage of reconstructing W&N's "Bitumen" oil paint. This important finding offers an explanation for the paucity of analytical evidence in previous attempts to identify asphalt/bitumen in paintings where this material was believed to have been used. In addition to clarifying the analytical results obtained from the investigation of the painting, O Cardeal D. Henrique…, the reference samples produced from the W&N reconstruction illustrate the strengths and weaknesses of organic analysis of highly processed complex mixtures."Alligatoring" ou "Bitumen cracking" são termos utilizados para descrever defeitos extremos encon- trados em pinturas a óleo do século XIX. Esta patologia sob a forma de fissuras e distorções severas da superfície pictórica resulta frequentemente numa perda de integridade da imagem. Este problema tem sido associado à utilização de tintas de asfalto/betume, sem no entanto existir uma compreensão clara dos materiais e mecanismos que contribuem para este fenómeno. Esta tese investiga este fenómeno a partir de uma abordagem multidisciplinar que visa contri- buir para o conhecimento de pinturas a óleo afetadas por este defeito extremo. A parte 1 centra-se na perceção que existe sobre este problema através de uma pesquisa bibli- ográfica, e introduz a pintura do século XIX utilizada como caso de estudo. A revisão rigorosa da lite- ratura revelou o preconceito existente criado pela perceção da ligação entre a aparência e a causa, resultando numa associação de defeitos em filmes de tinta castanha com a utilização de tintas de as- falto/betume. Devido a isto, o foco geral de estudos anteriores foi a deteção do asfalto, considerando- o isoladamente e como a principal causa nos defeitos de tinta. Esta visão simplista tem tido implicações significativas no estudo e análise de pinturas com “alligatoring” (efeito de pele de crocodilo), inibindo investigações mais abrangentes e subvalorizando outros materiais presentes nas pinturas que podem estar a atuar em combinação ou ser mais predominantes no mecanismo de deterioração. O estudo visual e químico da pintura a óleo O Cardeal D. Henrique recebendo a notícia da morte de D. Sebastião, de Marciano Henriques da Silva (1831-1873), pintado em Roma em 1861, que exibe “alligatoring” extremo, ofereceu desafios específicos devido à sua estratigrafia complexa e muito alte- rada, aliada à incerteza introduzida pelos limites de deteção analítica. Por essa razão, foi realizada uma abordagem multi-analítica utilizando Microscopia Óptica, Micro-espectroscopia de Raman, Microsco- pia Electrónica de Varrimento com Espectrometria Dispersiva de Raios-X, Micro-espectrometria por Fluorescência de Raios X Dispersiva de Energias, Micro-espectroscopia de Infravermelho com Trans- formada de Fourier, Espectroscopia Raman com Transformada de Fourier, Espectroscopia de Infraver- melho com Transformada de Fourier por Reflexão Total Atenuada acoplada a Microscopia Óptica, Pi- rólise-Cromatografia Gasosa acoplada à Espectrometria de Massa com derivatização usando Hidróxido de Tetrametilamónio e Espectrometria de Massa de iões secundários. Esta investigação indica que a deterioração da pintura pode estar relacionada com o aglutinante de óleo altamente hidrolisado, rico em ácidos gordos polares e diácidos, combinado com a falta de pigmentos capazes de estabilizar a tinta. A presença da camada translúcida de azelato de chumbo sobre a camada de preparação sublinha a complexidade da estratigrafia, dos materiais presentes, e dos possíveis mecanismos de degradação. A Parte 2 descreve a analise dos registos de produção de "Betume" castanho para tintas em tubos de óleo do arquivo e base de dados do século XIX da Winsor & Newton (fabricante de materiais para artistas britânico). Embora exista um número substancial de receitas de tintas castanhas de as- falto/betume publicadas em manuais para artistas do século XIX, os registos da W&N são uma fonte de informação detalhada e única sobre o produto preparado comercialmente que difere substancial- mente nos ingredientes utilizados e no método de preparação. A análise crítica dos registos de produ- ção da W&N para "Betume" revelou que a sua formulação foi normalizada na década de 1850 e que era preparado em duas etapas distintas e em dois locais distintos. Apesar da padronização dos ingre- dientes, esta investigação revelou que a empresa comsiderava necessário fazer ajustes em cada etapa de produção, a fim de obter um produto uniforme. Um registo de produção de 1858 foi selecionado e reconstruído, utilizando, sempre que possí- vel, materiais historicamente apropriados. A formulação da W&N para a tinta castanha de betume a óleo envolveu uma mistura complexa de ingredientes, alguns dos quais eram produtos produzidos e vendidos pela W&N. Estes foram reconstruídos individualmente, utilizando os seus próprios registos de produção, e incluíram óleo de secagem, verniz mástique duplo, acetato de chumbo, pigmento laca roxo, e o gel tixotrópico Megilp). As reconstruções foram analisadas utilizando Pirólise-Cromatografia Gasosa acoplada à Espec- trometria de Massa com derivatização usando Hidróxido de Tetrametilamónio, e Pirólise por Croma- tografia Gasosa Bidimensional acoplada à Espectrometria de Massa. As reconstruções foram compa- radas com a materia prima utilizada, o asfalto do Lago Trinidad, para determinar o grau de deteção deste asfalto após o processamento térmico em óleo de linhaça tratado com chumbo. Os resultados mostram que os marcadores asfálticos identificados no asfalto do Lago de Trinidad desaparecem na primeira fase da reconstrução da tinta a óleo "Betume" da W&N. Esta descoberta importante oferece uma explicação para a escassez de provas analíticas em tentativas anteriores de identificação do asfalto/betume em pinturas em que se acreditava ter sido utilizado este material. Para além de clarificar os resultados analíticos obtidos a partir da investigação da pintura O Cardeal D. Henrique..., as amostras de referência produzidas a partir da reconstrução da W&N ilustram os pontos fortes e fracos da análise orgânica de misturas complexas altamente proces- sadas

Health Hazards Manual for Autobody Shop Workers

[Excerpt] We will look at the principal occupational health hazards and exposures themselves and some of the related issues. We will look closely at the chemical composition of autobody shop products to see what components appear to be particularly hazardous, how you are exposed to them, and what you can do to minimize exposure. The health effects discussed for these products are based upon the exposure of the professional, not the consumer. This manual deals with chemical exposure only; other issues of interest to the autobody shop worker may include occupational exposure to noise and neuromuscular problems such as Raynaud’s phenomenon (possibly from pneumatic hand tools)

Residential lead hazards, nutritional deficiencies, and socio-cultural factors related to Hispanic children with blood lead levels greater than or equal to five micrograms per deciliter

One of the most significant public health successes during the late 20th century was the reduction of blood lead levels among children in the United States. However, lead continues to be a public health issue because it often affects minority children of lower socioeconomic status, who live in older homes. Young children are especially susceptible to the harmful affects of lead due to their vulnerable developmental state. According to research, the most common sources of lead exposure for U.S. children are lead-based paint and lead-contaminated dust in the home; This study examined residential lead hazards, nutritional deficiencies, and socio-cultural factors related to children with blood lead levels ≥ 5mug/dL in Clark County, Nevada. The results demonstrated that lead-based paint residential hazards may not be the most common source for childhood lead exposure for children. While the results on nutritional deficiencies and Socio-cultural factors related to Hispanic children were insignificant, evident trends were observed. These trends warrant the development for culturally appropriate lead prevention programs in Clark County, Nevada