You'll have seen this kind of thing before - dark smudges of soot or fat in corners, nicotine deposits on walls and water stains on ceilings. Another problem is show-through of wood components, such as staining agents and preservatives, resins, lipids and minerals.
To remedy this there are sealant paints. They prevent the show-through of such imperfections and also provide an excellent basis for the application of top coats. Use of sealant paints is thus important for any form of renovation work and application of these is essential for priming raw timber, particular oak, Meranti and Bangkirai. Some products even combine sealant, primer and top coat in one.