Investigation on the Effect of Multiple Passes in Plain Waterjet Cleaning of Paint

Paint removal process in automotive coating is widely used in vehicle component recycling industry. The need of utilization and recycling the automotive compo-nent without producing secondary pollution from the paint removal process is re-cently become a major concern globally. Water jet cleaning is a new method for paint removal and getting recognition because of environmental friendly and it is better than mechanical cleaning such as sand blasting, brushing with water, hy-dropneumatic cleaning, controlled dry sanding, low pressure water projection and low pressure water spray. The present study focuses on the investigation of effect of multiple passes in plain water jet cleaning on paint removal process. A new method of multiple passes treatment is applied in plain water jet cleaning to access its effect on surface roughness and paint removal rate. It was found that, with in-creasing of number of passes, the surface roughness and paint removal rate is slightly increase. It is also found that the increase in water jet pressure will in-crease the surface roughness and paint removal rate. This is probably because in-creasing pressure will leads to more energy to remove the paint. It is found also that the increase in traverse rate increase the surface roughness and decrease paint removal rate. Based on the present study, it is a high prospect to apply multiple passes of paint removal using plain water jet in automotive industry

Composition of the black crusts from the Saint Denis Basilica, France, as revealed by gas chromatography-mass spectrometry

The organic fraction of black crusts from Saint Denis Basilica, France, is composed of a complex mixture of aliphatic and aromatic compounds. These compounds were studied by two different analytical approaches: tetramethyl ammonium hydroxide (TMAH) thermochemolysis in combination with gas chromatography-mass spectrometry (GC-MS), and solvent extraction, fractionation by silica column, and identification of the fraction components by GC-MS. The first approach, feasible at the microscale level, is able to supply fairly general information on a wide range of compounds. Using the second approach, we were able to separate the complex mixture of compounds into four fractions, enabling a better identification of the extractable compounds. These compounds belong to different classes: aliphatic hydrocarbons (n-alkanes, n-alkenes), aliphatic and aromatic carboxylic acids (n-fatty acids, α,ω-dicarboxylic acids, and benzenecarboxylic acids), polycyclic aromatic hydrocarbons (PAH), and molecular biomarkers (isoprenoid hydrocarbons, diterpenoids, and triterpenoids). With each approach, similar classes of compounds were identified, although TMAH thermochemolysis failed to identify compounds present at low concentrations in black crusts. The two proposed methodological approaches are complementary, particularly in the study of polar fractions.This work was supported by the European Commission (project EV4K-CT2000-00029), the French Ministry of Culture (subvention de recherche chapitre 6698 20, exercice 2001), and the MCyT, project BTE2001-1277.Peer Reviewe

New insights on the chemical nature of stone yellowing produced after laser cleaning

9 pages, 4 figures, 4 tables, 1 plate, 14 references. This book mostly contains contributions by the invited lecturers at the 7th International Conference on Non-Destructive Testing and Micro-Analysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage. El libro consta de 328 páginas.Koen H. A.JanssensLaser c1eaning of stone monuments is nowadays a procedure widely used in restoration. However, one of the criticisms to the method is the controversial yellowing of the stone. In this paper, we present evidence that aliphatic and aromatic carboxylic acids and phenols, which are components of a yellow fraction isolated from black crusts, are not affected by Nd: YAG 1064 nm laser irradiation. We deduce that these water soluble compounds, which always impregnate the stone surface undemeath black crusts, cannot be removed by the laser beam when the crust is eliminated. This means that, at least, part of the yellowish aspect after laser cleaning, is linked to these remaining compounds.This work was supported by the European Comission (project EV4K-CT2000-00029), the French Ministry of Culture (subvention de recherche chapitre 6698 20, exercice 2001) and MCyT, project BTE2001-1277.Peer reviewe

Origin of salts in stone monument degradation using sulphur and oxygen isotopes: First results of the Bourges cathedral (France)

International audienceThe crystallisation of soluble sulphate salts is one of the most important factors of stone monument degradation. The origin of these salts is variable: marine, air pollution, building or restoration material. The lack of certainty about these sources represents a problem for restoration campaigns. The use of sulphur and oxygen isotopic tracers allows to discriminate the origins of materials and some stone deterioration patterns like black crusts (e.g. [Šrámek J., 1988. Sulfur Isotopes in the revealing corrosion mechanism of stones. 6th International Congress on Deterioration and Conservation of Stone,. Proceedings, ed. J. Ciabach. Nicholas Copernicus University, Torun, Poland, 341–345.]). First results obtained on the Bourges cathedral (France) show that the sulphur and oxygen isotopic composition of sulphates from external (atmospheric pollution) and internal (mortars, plasters and sulphates coming from stone sulphide oxidation) origins constitute well differentiated poles. The isotopic composition of sulphates implied in different stone deterioration patterns is well explained by a combination of these poles. The present study will be extended to other French monuments located in different lithological and hydroclimatic settings where contributions of sea salts and ancient chemical treatments are suspected