"Paint" is a liquid, liquefiable or mastic composition. This text deals with "commercial paints" sold in the "DIY" shelves, used in interior design, for protecting exterior surfaces or to cover all kinds of objects of everyday life as opposed to "artistic paints", used by artists-painters.
Legislation concerning "commercial paints" does not apply to "artistic paints".
Among commercial paints are products based on whether or not they are opaque and whether or not, on drying, they form an impervious film (film forming product), namely:
|Non film-forming||Coatings||Wax, impregnating oil|
The paint is generally in liquid form and is applied depending on its use with one or more coats, using a brush, roller or by spraying. The paints can also be in paste form and are applied with a knife (a small trowel). In the industry, paints are also used in powder form, applied by electrostatic spraying or dipping, which are then cross-linked.
In order to obtain a solid coating, it is necessary to dry the liquid or paste paints by evaporating the solvents. This step is usually followed by a cross-linking (stiffening) which improves the physical properties of the coating.
Elements of a paint (or a coat) usually consist of:
• fillers or filler materials: these insoluble powders, unlike pigments, only provide low opacity and mild colour (talc, mica, silica, calcium carbonate);
• pigments are fine powders whose role is to make the paint opaque, give it colour or garnish it (for example Titanium Dioxide, Sienna, Yellow Ochre, iron oxide, zinc oxide);
• binders or mediums, which bind the pigments/grains to each other and provide consistency and transparency (linseed oil, resins, Arabic gum, waxes, etc.);
• diluents or solvents, whose role is to make the binder fluid enough to allow for easier application of paints (turpentine, water, organic solvents, oil); after application, the diluents evaporate and the paint sets (it is said to have dried);
• additives are products that are used in small quantities to enhance certain properties of the paints, such as resistance to fire, to fungi, insects etc. Best known is the siccative additive, whose role is to enable the drying of paints.
Apart from pigments and binders, we find various products in paint that improve its elasticity or strength.