Everyone has heard of wood preservers but what are they, why are they so important and how do they work?
Although wood is an amazingly versatile and durable material, it can be susceptible to deterioration especially where mould, algae, fungi and wood-boring insects are likely. The best way to protect and preserve wood, including timbers that have been tanalised or pressure-treated is to use a wood preservative.
A neglected garden shed that has been allowed to rot and decay.
In past years, treatments such as creosote and engine oil were used to preserve exterior timber, however, as a greater understanding of the toxic nature of these products became known many were banned or restricted for commercial use only by strict government legislation. Thankfully, today’s domestic wood preservers are safer for both the user and environment.
Types of Wood Preservative
Most wood preservatives nowadays are manufactured with similar ingredients due to the government-led restrictions, however the formulas and the strength of those ingredients do vary. In layman’s terms:
- Clear preservers help retain the natural appearance of the wood
- Coloured preservatives act as a dual-purpose treatment and stain that change the colour of the timber
- Solvent-based formulas have been around longer and are known for their penetrative properties
- Water-based treatments conform to strict VOC (Volatile Organic Compounds) regulations being imposed by UK, European and worldwide governments, making them safer for the environment
Why Use a Wood Preservative?
In short, wood preservers help extend the useful life of wood by preventing wood rot and decay caused by mould, algae, fungi and wood-boring insects. Interior and exterior wood that has been preserved, treated and maintained can last for many 100s if not 1000s of years, making it a very eco-positive option.
How do Wood Preservers Work?
The key ingredients of wood preservers are biocides and insecticides with the most commonly used being Permethrin. Permethrin is an insecticide in the pyrethroid family. Pyrethroids are synthetic chemicals that act like natural extracts from the chrysanthemum flower. Other common ingredients include Iodo propynyl Butylcarbamate and Tebuconazole. Most modern wood preservers are safe for humans, animals and plants when dry, meaning that they can be used on sheds, fences, wooden trellis, dog kennels, stables, joinery and more.
Are Wood Preservers an All-in-one Solution?
Although wood preservers are great at protecting wood from biological threats, they only offer limited weather protection and direct contact durability. Some wood preservers contain a small amount of wax which means that rainwater will initially bead and run off treated wood. Surfaces treated with just a wood preservative however, will likely need re-coating every couple of years. Ideally, wood that has been treated with a preserver should also be treated with a suitable top coat such as a wood oil, wood paint or wood varnish. These top-coat products seal in the preserver and provide protection against weathering and wear from direct contact.
If overcoating a wood preservative with a water-based paint or varnish, it’s important to select a preserver that does not contain wax.
5 of Our Top Selling Wood Preservers
Although we sell dozens of wood preservers, here are just a few of our best selling products.
Barrettine Premier Wood Preserver
Barrettine Premier Wood Preservative offers microporous protection against wood rot, fungi, decay and mould as a deep penetrating solvent-based formula with wax and resin ingredients that help with water repellency. Due to this we only recommend using a solvent-based oil, varnish, stain or paint as a top coat if you wish, as water-based top coats will not adhere to the wax and resin base. Available in clear and an attractive range of wood tone colours.
Barrettine Wood Preserver for exterior timber – Ideal for garden sheds, fences and more.
Customer Review – Barrettine Premier Wood Preserver
The product is easy to apply, provided you don’t overload the brush and soaks into the wood. The boards on the house had two coats 3 years ago and still look good with little sign of green fungus (shady side). My neighbour has now decided to use it on his property.
Ronseal Total Wood Preservative
A highly penetrative, solvent-based formula, Ronseal Total Wood Preserver is perfect for use on all exterior timbers including garden sheds, fences, joists, doors and window frames.
Ronseal Total Wood Preserver – Available in clear and a range of colours for exterior wood
Customer Review – Ronseal Total Wood Preservative
Used for both my deck and my fence. Good coverage and easily applied using a brush. Natural colour which brings out the grain. Would recommend.
Cuprinol 5 Star Complete Wood Treatment
Available in clear only, Cuprinol 5 Star Complete Wood Treatment is a water-based, low odour and low VOC wood preserver specifically formulated for the treatment of interior timber. Deep penetrating formula ensures long lasting protection against insect attack, re-infestation and fungal decay.
Complete wood treatment for interior wood including floor boards, joists, joinery and more.
Customer Review – Cuprinol 5 Star Complete Wood Treatment
I ordered this product as I needed to apply a thin coating that got absorbed readily on old interior timbers and new Oak beams alike. Little evidence of any staining which was important. Applied via a spray nozzle and also a brush. Low odour and lasted a long time.
Osmo Wood Protector (4006)
A wood protective treatment that is free from biocides and preservatives. Osmo Wood Protector (4006) is ideal for treating wood in high moisture areas, such as wet rooms, kitchens and bathrooms. Especially suitable for woods that are susceptible to blue stain, such as Pine.
Osmo Wood Protector 4006 – A biocide and preservative free wood protector, ideal for interior, high moisture environments.
Customer Review – Osmo Wood Protector (4006)
I can only say that I needed an undercoat to protect the bathroom wood door from steam, moisture and similar. So using the Osmo brand made sense before using Osmo oil.
Sadolin Quick Drying Wood Preserver
A clear water-based wood preserver suitable for new and bare timber, Sadolin Quick Drying Wood Preserver is perfect as a pre-treatment before applying a wood stain, paint or other wood finish. Provides excellent protection for interior and exterior joinery against wood-destroying fungi and blue stain.
Sadolin Quick Drying Wood Preserver – A wax free clear preserver.
Customer Review – Sadolin Quick Drying Wood Preserver
A great product that goes on easily. It’s protecting my log cabin even before I get round to getting the top coat on. Good preparation should result in a long life.
Top Wood Preserving Tip
All wood, new and old, should be treated with a fungicidal wash or multicide wood cleaner before treating with a wood preservers. Why? Wood only needs to get wet or damp once for mould and algae spores to establish themselves in the wood grain. This can happen at any time in the transit or storage of the timber or the finished article including sheds, fences and decking boards. Although wood preservers will help to prevent mould, algae and fungi establishing themselves on the wood, they are not always effective at killing off already established spores within the timber.
For this reason, we always recommend that all wood is initially treated with a fungicidal wash or mould and mildew cleaner to kill off any existing spores in the wood grain before applying a preserver.
Want to Know Even More About Wood Preservers?
For more information about wood preservers and their uses, call our experts on 01303 213808 to help with project advice and product recommendations.
We love to see before, during and after photos of any wood finishing project. If you would like to share your project pictures with us and our followers, you can either send us some photos or share on our Facebook or Instagram pages.
62 comments
Reply to Samantha Taylor:
Thank you Samantha. I really appreciate your advice and will consider the product you recommend.
Regards Mandy.
I live in a warm humid climate. The crawlspace over the years has experienced growth of surface fungi that is discoloring the joists, and it needs some remediation. The proposals that I have received recommend cleaning the joists with a disinfectant product, which will remove the existing mold but won’t prevent future mold growth. Is there a product that can be applied after the disinfectant treatment that will be substantive to the wood and prevent future fungal growth? How long could I expect the efficacy to last, because once the insulation is replaced, it won’t be possible to treat the joists again.
Reply to Tom H:
Hello Tom,
Your best bet is a good quality preserver such as the Premier Wood Preserver (https://www.wood-finishes-direct.com/products/barrettine-premier-wood-preservative) you can apply three liberal coats of this to your joists and it will last a few years as I suspect they will be mostly covered.
Dark damp places are a perfect space for mould and algae to grow and so it is likely to return, however a preserver will certainly help to keep it away for longer and protect the wood for a good period of time.
Hi,
a couple of questions specifically regarding the solvent based ‘Barrettine Premier Wood Preserver’
1…is it ok to mix one of the coloured variants with the clear one in order to get a slightly lighter shade of colour? (I’ve just purchased both from you.)
2…can this be applied to damp wood? (I’ve had a fair bit of rain while constructing my new shed!)
Thanks.
Reply to Steve:
Good Afternoon Steve,
Yes, there is no reason why you could not mix the colour and the clear to reduce the tone of the coloured option. I would recommend a very thorough mixing once combined to ensure even colour throughout and perhaps a smaller ratio mix and test area to make sure you are getting the desired result.
However I would not recommend application to wet or damp wood, even wood that appears dry may be holding moisture if it has been subjected to lots of rain over a period of weeks and I would have to recommend a period of a few days of dry weather before considering the application of any products. I know it is not always easy in the UK with the unpredictable weather, however it will ensure a longer life for the product and help to avoid trapping moisture in the wood, which can lead to mould and decay.
I hope that helps with your project, if you do have any further questions please do not hesitate to get in touch.
All the best Samantha.
Hello,
I’m building a workshop / shed / log store out of marine ply and tantalised wood. What Would you suggest is the best preservative / treatment for it.
Many thanks
Ian
Reply to Ian:
Good Afternoon Ian,
Thank you for getting in touch, quite a project! I would recommend the Barrettine Premier Universal Preserver (https://www.wood-finishes-direct.com/products/barrettine-premier-universal-preservative) as a good place to start. Its a clear preserver and wax free so you are able to apply most top coat products over the top to achieve your desired colour result.
Then for the top coat which will help prevent UV damage and moisture ingress, I would recommend considering an oiled product, such as Barrettine Decking Oil (https://www.wood-finishes-direct.com/products/barrettine-decking-oil) its very versatile and can be used for a wide range of projects as well as decking. The oil penetrates the wood surface and adds colour and protection, whilst still looking and feeling very natural. there is also a clear option in this range and this will still slow down UV damage, although not as much as a coloured oil will.
Another option to consider is the Osmo Natural Oil Woodstain (https://www.wood-finishes-direct.com/products/osmo-wood-stain-protector) again a penetrating oil, however this one comes in sample sachets or tins to allow you to do a test area. And I would recommend this, the wood type, age and condition, will all impact on the result to be achieved and can sometimes be unpredictable.
And the benefit of using an oil is that they are super easy to maintain over time, as the protection or colour fades you are are able to simply clean the surface and once dry apply a fresh coat to top up. Again a test area is recommended for this to ensure the wood is ready for more oil uptake. You do not want the oil to be over applied as this results in drying on the surface of the wood and can mark easily
For more help and advice please do feel free to get in touch with our friendly team.
Kind Regards Samantha.
Hello – I have a log cabin that has been treated with a single coat of Blackfriar Wood Protector
What would be a good product to use as a top coat? I’ve been recommended Sadolin Classic but like the colour of the cabin so would something like Sadolin Clear Coat be suitable?
Thank you.
Reply to Simon:
Hello Simon,
The Blackfriars looks to be a preserver that contains wax, this is what gives it the moisture repellent element. This means that not all products will adhere well over the top and I think Sadolin is likely to be one of those products.
As a general rule for exterior finishes, if you want to use a paint, varnish or top coats stain, you need to use a wax free preserver. Preservers that do contain wax can be used as stand alone products for fencing for example or if you are applying an oil over the top.
For Log Cabins I do tend to recommend an oiled finish anyhow, oils penetrate the wood and will not peel and flake down the line. Its fair to say they are not as long lasting as some stains or paints, however the benefit comes with ease of maintenance. No stripping required just apply a fresh coat a clean dry surface when the wood needs it, usually annually or bi annually. I recommend the Barrettine Log Cabin Treatment (https://www.wood-finishes-direct.com/products/barrettine-log-cabin-treatment) as a good option to consider.
If you did want to go with a Sadolin Extra Durable Clearcoat (https://www.wood-finishes-direct.com/products/sadolin-extra-durable-clearcoat) its best to try a test area first and see if the product will adhere to the surface of the wood, bearing in mind that if it does there will be no guarantees for longevity, or wait for a period of 6 months for the wax to naturally start to wear and then consider application.
Its also worth bearing in mind that application of a clear product, oil or varnish, offer little UV protection whereas the application of a colour, even a very light one will greatly reduce the silvering from UV damage.
All the Best Samantha.
Reply to Samantha Taylor:
Thank you for the quick and detailed reply.