The paint section of your DIY store, whatever it is, is a bit like the yoghurt section of your supermarket: there is a quantity of impressive paints, each with their characteristics, their instructions for use, their colors of course. , their rendering (matte, satin, glossy) and their destination supports. So how to find it?
Can exterior paint be used indoors?
Imagine that you have found the paint that suits you to redo all your shutters, for example, and that you decide to use the bottom of the can of paint to repaint a small stool in your living room, know that this is not at all a good idea.
If the paint department distinguishes paints intended for the exterior from those made for the interior of your home, it is not the result of chance or a marketing argument, for once!
Exterior paints usually contain specific chemical additives, such as pesticides, which can be toxic for indoor use. Conversely, paints for the interior do not have components ensuring great resistance to UV or humidity: used outside, they would not last long.
Glycero paint or acrylic paint?
Oil-based paints smell strong and require good ventilation if you paint indoors because they contain volatile organic compounds (VOCs) which are harmful to the environment and to health. They are thus composed of solvents which act a bit like a preservative while waiting for you to use the paint; it is thanks to them that the paint remains liquid in its pot, and that once spread, they evaporate to make your paint dry. In addition to the solvents, the resins in the paint contribute to the adhesion of the paint to the surfaces. The pigments give the desired color to the paint. And finally, the additives are a lot of biocides to prevent the formation of fungi and repel insects, as well as to allow you to keep your opened jar hermetically sealed for several months. This paint can be cleaned with white spirit.
In general, glycerol paints are more resistant than acrylic paints : they are therefore preferred for the exterior, whether it is a wooden or metal support.
Among these additives, some are specific to interior paints (kaolin) to make them more resistant and others to exterior paints (zinc oxide) to make them shine and prevent discoloration and mould.
Acrylic paints are also called water-based paints : they are mainly used indoors, probably also because they smell much less strong than the others, wash with water and dry faster, but don’t forget to open the windows to avoid poisoning yourself despite the absence of odor. Contrary to what one might imagine, they are not without risk for the environment. They certainly contain fewer solvents (5 to 20%), which are most often alcohols or glycol ethers, the latter being suspected of having an impact on male fertility. In addition, chronic exposure in your interior, after the painting is finished, to these glycol ethers derived from butyl glycol, is potentially risky for your health.
Another criterion of choice is to be taken into consideration when choosing your paint: it is the environmental pollution linked to the product. There are two official labels: the European eco-label and the NF environment mark.. They are always good to take. Next to it is the pollutant emissions label which resembles those of household appliances: it displays the pollutant emissions. As the thresholds used for these pollutants are very high, it is absolutely necessary to limit yourself to paints classified A+ for its emissions of harmful substances: in the absence of 0 emissions, you will limit excessive inhalation.
Be careful to choose your paint carefully: do not do it lightly and beware of the advice of salespeople, who are often interested in sales and not in the harmlessness of the products.