Emissioner i slutna utrymmen Med speciell inriktning på emissioner av formaldehyd och organiska syror

Abstract

This study aimed to evaluate the levels of formaldehyde and organic acids that can build up within enclosed spaces. Another goal was to compare two types of paints that can be used as coating barriers within showcases and in turn compare them to the modern, and by many highly recommended, material of Marveseal®. A low volatile waterborne alkyd/acrylate paint and a two component polyurethane paint was compared to Marveseal® in two series of experiments. One series measured the level of formaldehyde, and thus the effectiveness of the three chosen barriers, and the other series measured the level of volatile organic acids, both the acids emitted from the paint itself, and that of the wood. One box in each series were not treated at all and was used as a reference. The fact that different types of materials emit volatile organic compounds have long been known. The prime concern for museums has been the emission of formaldehyde and organic acids, such as acetic acid and formic acd. Inorganic pollutants, such as nitrogen oxides, sulphur oxides and ozone, are also of concern. The various effects these have on artefacts have been studied, especially the corrosive effects on metals and calcareous materials. However, the effects on paintings and their different components, such as pigments and varnishes, have not been quite so thoroughly investigated, even though some studies have been carried out. Completely airtight showcases, or showcases with very litte air exchange rate, are common at museums. They serve as protective ”boxes” for the exhibited artefacts inside against external airpollution, theft or vandalism. They can however also serve as a trap for internally emitted organic pollutants such as formaldehyde. In museums today staff and conservators work under tight timeframes, and the materials that are to be used in an exhibitions may not be given the time they need to be stable enough and safe to use. The results in this study showed that materials that have been recommended as so called safe materials, may not be as protective as they are known for, if they are not given the correct time for drying or if they are applied wrongly.