Wood stains: the complete guide

Have you bought an impregnating agent for wood but don't know if it is the right one for your purpose? Is it better a water-based or a solvent-based one? Are you wondering what VOCs are? Don't worry, you will find the answers to your doubts in this article.

In recent years people often talk about woodstains, but they are sometimes confused with paints or varnishes. In this article, we will explain what a woodstain is, what its uses and characteristics are and how to identify the safest products.

After discovering how easy it is to use this type of product, you will no longer be able to do without woodstains to protect and colour your wood!

A wood stain is a product that serves to protect and/or colour wood and that penetrates into the porosity of the treated object, without forming a surface film. Precisely for this reason, it allows the wood to breathe more, permitting a correct exchange of humidity with the environment.
The best woodstains also do not alter the surface of the material and are able to let the grain show through, giving a pleasant natural effect.

There are wood stains with specific characteristics, which meet different needs. If you want, for example, to colour the wood and protect it from the weather, you should choose a coloured, water-repellent product.

Woodstains differ between those suitable for interiors and those designed specifically for exteriors. They can provide basic protection for the material or they can have specific biocide functions.

Indoor woodstains are usually used to treat the load-bearing structures of a building, roofs, furniture, floors and, more generally, all wood that is not directly exposed to atmospheric agents. 
On the other hand, it is better to use a wood stain for exteriors when you have wooden objects or structures that are constantly exposed to light radiation and atmospheric agents and can therefore more easily undergo physical, chemical or biological degradation. Where is wood usually used for exteriors? Thinking mundanely of your house or that of your neighbours, wood can be used for shutters, pergolas and gazebos, garden furniture, fences or flooring. All these objects can be protected with a suitable impregnating agent.

There are environmental situations in which wood is under greater stress or the risk of attack by fungi, bacteria or xylophagous insects is higher. If, for example, you live in a very humid environment, the risk of fungal attack will increase and you should use a woodstain with biocide characteristics against fungi.

In the case of special uses of wood, such as nautical jetties or poolside decking, the most suitable woodstain will be one that is resistant to chlorine vapour and salt solutions. An example is Lignum Hydromil.

Wood is sensitive to UV radiation, which leads to an ageing of the material that can be more or less rapid, depending on the type of protection you provide. If you take a piece of wood and expose it to the outside, you will notice that it will first yellow and then tend to turn grey. This is the classic ageing process that we can slow down through the use of woodstains, especially coloured ones.  Coloured wood stains also have the purpose of protecting the wood from light radiation: the darker the colour (e.g. walnut or dark walnut), the greater the protection from the sun's rays. In addition to this, there are products that also contain specific additives to filter UV rays.

With woodstains, you can give free rein to your imagination as there are many different colours on the market, ranging from white to yellow, brown to red, and even green and violet. 
Precisely because of the characteristics of this type of product, it is generally possible to overlap several colours to achieve special effects, much loved by architects or DIY enthusiasts who create, for example, Shabby-style objects.

With regard to finishes, there are impregnating agents that maintain the naturalness of the wood, so that when you touch the material you do not feel the treatment. If you want to accentuate the feeling of softness to the touch, you can use products that give a waxed effect to the wood, such as Lignum Hydromil, or that make the material's appearance 'warmer'. In the latter case, woodstains based on linseed oil (or other drying oils) are the most suitable. An example is Lignum Nature.

Until a few decades ago, there were few impregnating agents on the shelves of hardware stores and paint shops, and most of them were solvent-based. Over the years, technologies have evolved and sensitivity to human health and the environment has increased, thus the emergence of water-based woodstains. Products of this type sometimes present two problems: greying around knots and raising of the fibre, which requires sanding the surface after treatment.

So is it better to use a solvent-based or water-based woodstain? Water-based products on average have a lower content of Volatile Organic Compounds (VOCs) than solvent-based ones, making them less of an impact on the environment and easier to dispose of.
"What about greying and fibre raising problems?" you may be asking yourself. We at HDG have developed a range of woodstains that solve these problems, so there is no longer any need to sand the surface.

Woodstains are usually easy products to apply, both when dealing with new wood and when doing maintenance on an already treated material.

In the case of new wood, it is advisable to first apply a biocide treatment (fungicide and/or against woodworm), especially if the material will be placed in an area with high humidity. If there are any holes or cracks, these can be closed with wood filler so that the surface is smooth and homogenous.
 After removing loose dirt from the wood, if the surface is dry, the impregnation treatment can be applied.

The product should be applied following the direction of the grain and can be applied by brush, roller, sponge or spray (with a paint gun). On an industrial level, wood can be treated using impregnating machines, as we show you in this video.



In addition to classic flat brushes, the best woodstain can also be applied using a pad, such as Hydrovelvet.

For the maintenance of treated wood, it is usually sufficient to clean the surface with a specific cleaner and then reapply the woodstain. Many people wonder when maintenance should be done, but it all depends on the type of wood and where it is located. Maintenance is usually required when surfaces are dirty and when they begin to show the first signs of discolouration and/or greying.

If you have changed your mind about the colour applied and want to use another one, simply plane or sand the wood to remove the coloured surface layer. Solvents can be used to remove the treatment, but this method involves the use of products with specific hazards. Better arm yourself with sandpaper and patience! Once the colour has been removed, simply wipe off the dust and apply the chosen product.

How can you tell if a woodstain is safe for the environment and for the operator or end user? The answer is quite simple. All information on the degree of hazard of a product must be provided on the packaging label.

If the product contains biocidal active ingredients or additives that cause the woodstain to be labelled as hazardous, the specific hazard pictogram must be indicated on the label together with one or more risk phrases and one or more precautionary statements. The image below provides an example of correct labelling.

If the product does not show any particular symbols, then you have a non-hazardous woodstain on your hands.

Another piece of information that woodstains must mandatorily report on the label is the VOC value (Volatile Organic Compounds). This information is regulated by directive 2004/42/CE and by legislative decree no. 161/2006, which indicate the VOC emission limit values for certain types of paints and varnishes (including woodstains). A correct label should therefore state the subcategory of the product, the relevant VOC limit value expressed in g/l and the maximum VOC content expressed in g/l of the ready-to-use product, as shown in the image below and as we explain in more detail in our article on volatile organic compounds.

We hope with this article we have clarified your ideas on woodstain. If you have any other questions and curiosities, please do not hesitate to write to us! 

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