In order to put the current coatings object of this chapter into perspective, Table 3.1 presents the classification proposed by LNEC—Laborahmo Nacional de Engenharia Civil (National Laboratory for Civil Engineering) [9, 10]—for coatings for interior wall surfaces, where the ones dealt within this chapter are shaded.
According to this classification, interior coatings fall within the following four categories:
• Smoothing coatings—to give the wall planeness, verticality and surface regularity
• Finishing coatings—to give the wall a smoothing complement, thus guaranteeing in most cases a pleasant visual look
• Water-resistant coatings—to provide the finishing coat in walls in locations where water is frequently present or cleaning is made by wet means
• Decorative coatings—to provide the aspect intended by the users in terms of visual comfort, when the underlying coats do not do it by themselves
In order to present a more specific classification of current gypsum-based coatings, Table 3.2 shows the classification proposed in standard EN 13279-1: 2005.
The historic introduction leads to the following global classification that will be used in the next sections:
(a) Traditional gypsum plasters made according to ancestral proceedings
(b) Premixed gypsum plasters, whose constituents are all preselected and mixed in the factory and are applied on-site by spraying
(c) Premixed synthetic plasters, whose composition includes synthetic resins