Water vapour transmission properties of linseed oil paint
Tallinn University of Technology, Tartu College, Department of Technology, Puiestee 78, EE 51008 Tartu, Estonia; *Correspondence: email@example.com
Linseed oil paint has been in use in indoor and outdoor decorating for a long period of time. It is not easy to date the first findings but there are signs of using linseed paint at least in VIX century in some areas of Afghanistan and during the renaissance period in Europe. It is also known as a good preservative material for wood. Indoor finishing materials considerably influence the indoor climate (temperature, RH, ventilation rate) because of their moisture buffering ability. Moisture buffering occurs because of the sorption and diffusion properties of materials (wood, plaster, gypsum board etc.). As paint is a cover for those materials, the knowledge about material water vapour transmission properties is essential for evaluating hygrothermal properties of boarders and the co-action of paint and substrate (plaster). There could be products with different properties referred to as ‘linseed oil paint’.
In the current study six handmade paints with different recipes including two primers and two commercial paints were under investigation. As for interior works, one layer of paint could be used as well therefore the samples were covered with both – one and two layers of paint. The thickness of paint layers varied from 0.8 and 6.2 μm for one-layer primers, from 11.3 to 26.9 μm for one-layer paints and from 17.8 to 40.7 μm for two-layer paints. Water vapour transmission properties were determined by using EVS-EN ISO 7783 standard.
Water vapour diffusion equivalent air layer thickness sd was estimated as 0.1 and 0.2 m for 1-layer primers, 0.2 to 0.9 m for 1-layer paints and 0.4 to 0.9 m for 2-layer paints. The information gathered from the experiment enables to get an overview of the different properties of ‘the same product” and use the data in hygrothermal calculations.