What is stain when to use it how to apply it ?

In charge of protecting and decorating exterior wood, stain has benefited from technical progress to become an essential product in the maintenance of this natural material. Discover its peculiarities.


Presentation of the stain

Gates, shutters, doors, windows, pergolas: wooden structures are victims of many attacks, to name only UV rays, insects, mould, humidity, fungi or even frost. In order to protect them from their natural enemies, the application of a stain becomes essential. In addition to its protective role, it also has a decorative function. Today, this product is inseparable from wood maintenance operations due to its multiple properties.

Water-repellent, it protects the wood from moisture penetration and thus prevents the formation of fungi and moss. As it is also microporous, the wood can breathe. The water is therefore properly evacuated and this feature prevents the material from rotting. But that’s not all. When colored, the stain is able to protect the material against UV rays, thanks to the pigments present in the product. This way it doesn’t turn grayish over time. In fluid or gel form, you can use it on both horizontal and vertical surfaces.

How to choose the right stain for wood?

On the market, there are two main varieties of stains. On the one hand, there is glycerophthalic stain which has a strong odor but is only used outdoors. This product has the advantage of being self-cleaning while having a good covering power. However, it takes up to 24 hours for it to dry completely.

The acrylic stain when it has a faster drying time and emits almost no odor. But this product has its limits: it does not manage to resist UV rays for long and is not very durable over time. Ideally, it should be used on already stained surfaces.

Take care of the environment! Be aware that a stain made up of solvents has a higher content of Volatile Organic Compounds (VOC) than a stain in the aqueous phase whose tools are cleaned with water. Water-based stain is permitted for sustainable and environmental constructions. Look at what the label indicates for emissions into indoor air and favor stains with the Ecolabel and NF Environnement logos.

Last point: when choosing the stain, be sure to check its dry extract content which corresponds to the non-volatile materials, active materials, pigments and binders deposited on the surface after application and drying. Thus, if the stain contains less than 30% dry extract, it can last between 2 to 3 years. Between 30 and 40%, the weather barrier is greater, allowing the product to last up to 6 years. Finally, when the dry extract is more than 50%, the shelf life can reach up to 10 years.

How to apply stain

Performed by brush, brush, spray gun or roller, the application is relatively simple. It should only be done on a sound, dry and clean surface. So, when it comes to new wood, a simple dusting is enough. On the other hand, if the support is varnished or painted, it will first have to be stripped and cleaned.

Once this is done, apply the stain to at least two coats. Between the two, respect a break time according to the manufacturer’s recommendations. On wooden structures heavily exposed to bad weather, the application of a third coat should be considered. In addition, on hard woods, it is advisable to apply an undercoat beforehand in order to benefit from better adhesion.

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