How Does Wood Preserver Work in Protecting Wood?

Last Updated on January 5, 2023

Wood preservers are essential to keeping exterior wood in good condition by extending its lifespan and improving its looks. Unfortunately, insects, mould, and fungi can all attack timber, making it unsightly and even unstable.

Add in the sun’s UV rays and copious amounts of rainfall, and it’s not hard to see why you need to protect the wood from rot and decay, as well as general weathering and wear. So, how exactly does wood preserver work?

What Does Wood Preserver Do?

Wood preservers are essential to protecting exterior wood from the elements and insects, mould, algae, and fungi. A preserver is a chemical treatment that penetrates the wood surface to protect it from rot and decay by establishing an external layer of protection. This enhances durability, so your exterior wood will last for much longer, and in a much better condition, than non-treated wood.

Wood will easily degrade if not sufficiently protected. A good wood preserver will protect and extend the life of your wooden outdoor objects and enhance their looks in the process. Without a wood preserver, you risk wet rot occurring where the wood will decay with high moisture levels.

Rather than paying out to replace garden decking, furniture, and wooden flower bed borders, applying a fungicidal wood preserver will help to prevent both wet rot and dry rot from occurring.

What Is the Difference Between Wood Treatment and Preserver?

Wood preservatives are absolutely the best choice for “preserving” timber. They should contain active ingredients and be registered with the HSE. You can check the packaging for its HSE number to verify that your product qualifies as a preservative.

While even the best wood preservatives can benefit from being followed up with an additional topcoat of wood varnish, wood oil, or paint, a wood preservative alone will still give you much better levels of protection than treated wood.

Wood treatments, such as wood oil, wax, and wood stain, enhance timber’s surface appearance and protect the elements. They are best used on timber that has already been pressure treated or treated with a wood preservative at home.

This will ensure that your exterior wood is fully protected against fungi and insect attack, as well as sealing in the preserver and providing greater protection against damaging UV rays and weathering.

Different Types of Wood Preservatives

Three main types of wood preservatives are designed for at-home application: water-based, oil-based, and solvent-based wood preservatives. It is also possible to purchase pre-treated timber that has already been infused with chemical agents to protect it against decay.

Water-Based Wood Preservatives

As one of the cheapest and most readily available types of wood preservatives on the market, water-based wood preservatives are a popular form of timber protection. This type of wood preservative typically features copper-based compounds, although silicate-based versions are also available.

A popular choice for garden sheds, fencing and exterior plywood, water-based wood preservatives are more used and more environmentally friendly than solvent-based wood preservatives. They are also non-flammable and do not give off harmful odours.

The main disadvantages of these products are that they contain water. In addition, using water-based preservatives can sometimes lead to the swelling of more porous woods, and they are also less penetrative than other types of wood preservatives.

Oil-Based Wood Preservatives

Oil-based protectors penetrate more deeply into the wood grain, thus making them very easy to apply.

As they are insoluble in water, they provide a highly weather-resistant finish. However, their insolubility in water means they have to be dissolved in organic solvents, often petroleum, resulting in high levels of VOCs (volatile organic compounds).

We recommend checking whether your oil-based preservative will be suitable for enhancing the look of any coloured wood, as well as if it can be painted or varnished after completion.

Solvent-Based Wood Preservatives

A solvent-based timber treatment will tend to be more deeply absorbed for excellent levels of protection. Unfortunately, despite the lack of heavy metals, this type of wood protection gives off high levels of VOCs, making them less safe to apply than other types.

However, you can find some newer versions of solvent-based wood protectors that use organic compounds, making them a better choice for yourself and the environment.

How to Apply Wood Preserver

Before you start applying wood preservers, make sure that you have read all of the safety warnings and verified that you have all of the necessary equipment to hand.

Note that if the exterior woods that you will be treating are near to or part of a bat roost, the government provides a list of suitable wood treatments as well as a helpline. This is because bats are a protected species by law, and only certain wood treatments can be used in their vicinity.

1. Make sure your wood is free from all surface coatings. These include bark, varnish, and paint.
2. Whether it’s a garden shed or fencing, each surface must be treated.
3. Two coats, or more, should be applied. Ensure that your timber is completely dry before starting and allow it to dry out fully between each of the coats.
4. Use a large brush, and make sure that you stick to the recommended coverage rate. You will need to flood the timber surface using a large brush rather than applying paint. Penetration of the wood grain is significant to protect your wood against dry rot as well as wood-boring insects.
5. Pay particular attention to the end grain. If possible, submerge the ends of non-treated timber in a bucket of wood preservatives to ensure optimum absorption levels.
6. While pressure-treated wood will be resistant to dry rot and insect attacks, you may still want to treat it to ensure maximum protection against water, especially horizontal surfaces prone to pooling which can easily result in warping, cracking, and mildew growth.
7. Spray treatments can be less time-consuming. However, you must have the correct equipment to ensure a low enough pressure to prevent the treatment from simply misting rather than penetrating. As with a brush application, you’ll want to coat the surface for optimal absorption thoroughly. Two or more coats will still be required.

Can You Paint Over Wood That’s Been Treated?

If you are looking to paint your treated shed a particular colour, first of all, make sure that your timber treatment is compatible with topcoat finishes. Water-based timber treatments are the best to use when planning to paint your shed a specific colour. Otherwise, you could opt for a wood preserving treatment with a wood stain included.

Before you add a coat of paint to your preserved timber, it must be completely dry. Adding an exterior primer can help to provide better adhesion and improve the depth of colour. You can also lightly sand the surface between each coat of paint for the very best results.

If you are looking to paint pressure-treated timber, it’s best to wait and ensure that it has fully dried out. New pressure-treated boards can take several months to dry completely, so don’t be in too much of a rush to get your project painted. A primer is also recommended before you start painting to ensure that you get good adhesion.

Can You Use Wood Preservative Without a Topcoat?

If you don’t want the hassle of painting or varnishing your shed or fence after treatment, look for a wood preserving treatment that contains wax or a stain. Standard wood preservers are designed to be used with a top coat to ensure full weather protection. Therefore, if you aren’t planning on painting a specific colour, look for an all-in-one treatment to save yourself time and hassle.

If you use a standard timber preservative without any wax, you may need to recoat your timber every few years to ensure it remains protected. Using an overcoat will help to seal in the preservative for longer-lasting, better results and enhanced protection from the weather and direct contact.

Standard products protect against insects and fungal invasions, but they only offer limited protection against weathering and general wear. So, while you can use go without a topcoat, it’s much better, in the long run, to make sure that your timber is better protected with an extra layer.

Treating Old Fences or a Decaying Shed

Wood preservatives are designed to be used with new wood to prevent problems from occurring. If you didn’t treat your exterior wood and see the negative effects of not doing so, you could still use a timber preservative to prevent further degradation.

First of all, you will need to strip back the surface to ensure that the timber is free from any paint residue, dirt, or dry rot. Next, you may need to cut out and replace any decaying sections or consider using a wood hardener treatment.

After sanding back the surface, make sure that the wood is completely dry before applying your timber preservative as directed. If you don’t have the time to sand back the entire surface, you could pressure wash the exterior before allowing the surface to dry out fully. Don’t forget to add a topcoat if required to seal in your preserving treatment and ensure extra longevity without having to recoat frequently.

The Solution to Your Wood Problem

Without sufficient protection against harmful elements, as well as insects and fungi, your fencing, decking and garden shed will soon start to deteriorate. How does a wood preserver work? It protects wood from various conditions that can degrade or deteriorate its quality. Using a wood preserver, you are taking care of your wooden furniture and safeguarding your investment. You can trust that you will save plenty of time and prevent unnecessary hassle at a later date trying to repair damages.

Timber preservation treatments have undergone huge improvements in recent years. However, suppose you are worried about destroying the natural beauty of your item or breathing in harmful gases. In that case, today’s water-based treatment provides you with more eco-friendly options that are better for your health and nature in a range of natural-looking finishes.

Have you tried using wood preservers for your wooden belongings? How was your experience? Do you have other tips you’d like to share with others when using wood preservers? Share your thoughts in the comment box below!