Лако-красочные материалы — производство

Although gold is commonly believed to be a noble (i. e. low-reactivity) metal, it has fascinating adhesion properties. For example, if a sheet of gold is rolled up in normal writing paper and left for a certain time, the glue residues originating from the paper will adhere strongly to the gold surface such that it cannot be removed without causing mechanical impairment to the metal surface. This phenomenon has been recognized for many centuries, one example being the process of gold­beating, where the metal leaves are stored between layers of Japanese paper that do not contain binding glue. Alternatively, when applied in leaf form, gold adheres very well to many natural materials which have been sized with ‘gold oil’ to create very long-lasting and weather-resistant surfaces. The adhesion of gold leaf is very resistant, even in humid ambient conditions, despite the gold leaf itself being soft and having a low resistance. Consequently, the regilding of historical monu­ments is only necessary when erosion has led to damage of the gold leaf (see Section 8.16.4). This effect cannot be explained by standard adhesion theories; rather, the only possible explanation is that during the early stages of its manufac­ture, organic residues from the goldbeater’s skin (the outer membrane of ox intestine between which the gold leaf is beaten) are bound tribochemically to the gold leaf in quantities sufficient to provide adhesion by polymer diffusion when the gold leaf is applied to the gold size.

3.3.2