The Downsides Of Treating Fences With Creosote, And The Alternatives You Can Use

5 February 2015

Eugene Vargas

For decades, creosote was the preservative of choice for treating and preserving your fences and fence posts, and was used by homeowners and tradesmen alike. Generally, the pungent substance sold as 'creosote' on the open market was actually a blend of two different creosotes: wood-tar creosote, the substance used in preserving smoked meats, and the more potent coal-tar creosote. This traditional blend is, unfortunately, no longer available commercially, and for good reason. Many wood preservatives advertising themselves as 'creosote substitutes' have filled the gap in the market left behind, along with more modern, environmentally friendly alternatives.

What's wrong with creosote?

After some nasty experiments on lab rats, coal-tar creosote was found to be a powerful carcinogen, causing malignant tumours in a matter of weeks. Naturally, the substance was banned from being sold to the general public in pretty short order (it is still available industrially, but only for industrial and farming purposes).

Creosote substitutes

You can often spot these bearing similar names to the original product and their general purpose is similar: to provide a substitute as close to creosote as legally possible. They can contain a variety of substances depending on brand and formulation, but most are petroleum derivative bases with synthetic additives. They are designed to not only preserve wood, but also to provide a similar attractive stain. Some brands are even designed to smell like the real thing, for better or worse.

Most users consider this an adequate replacement, albeit with a little less longevity. The main problem with this stuff is application -- many users apply it to untreated wood with a brush, roller or spray gun, and expect it to preserve a fence indefinitely. In reality, traditional creosote was generally reapplied in this way to fence wood that had already been soaked in creosote prior to sale, often for lengthy periods. Modern, prefabricated fences are often dipped in other preservatives rather than soaked these days, so naturally the results won't be up to scratch unless you choose to soak new fence panels yourself.

Natural oil-based sealants

If you wish to abandon the creosote road entirely, a range of wood sealants based on linseed or tung oil are also available. These, properly applied, will protect your fence wood against fungal damage and rot, and have the added effect of making your fence functionally waterproof, reducing moss and lichen buildup and protecting against warping and cracking. They are also available with a variety of stains to give you the shade of wood you desire, as well as transparent blends if you wish to retain the original colour of your wood.

There are two main downsides to this approach -- the first is you will have to reapply the oil much more frequently than creosote, as often as every year if you have bad luck with the weather. The other is that most blends retain none of the insecticidal properties creosote has. This is obviously much better for the environment as a whole, but it does leave your fence open to attack from borrowing insects like wasps, termites and ants.

Synthetic sealants

These sealants are usually silicone or polyurethane based, and can be inexpensive to purchase. However, opinion on how good they actually are varies wildly, and many users have complained of unpleasant wood colour and greying resulting from their use. Seeking out the opinion of someone who has personal experience with these sealants is recommended.

Home brews 

Many DIY enthusiasts have come up with their own solutions for the creosote problem, creating their own preservatives from various materials. Suggestions range from credible to crackpot, but here are a couple of options that are known to work well:

• Used motor oil, thinned with kerosene or diesel, is often used by farmers to preserve boundary fences, and is generally well-regarded for its longevity as a wood treatment, as well as it's anti-rot, fungicidal and insecticidal properties. Only choose this option if you don't mind your fences coming out a dull shade of grey-black, and don't plan on touching them for a couple of months unless you enjoy being coated in sticky black filth. Plus, It's arguably as bad for your health and the surrounding environment as creosote is, and may be just as illegal in your province.
• Acetone and polyester resin is a less extreme solution, and while you'll probably have to add other chemicals to protect against rot and fungus, it does penetrate wood deeply and quickly, without leaving an unpleasant colour. It will, however, leave your wooden fences feeling distinctly 'plastic-y'.

For tips on how to maintain your fence, contact a fencing contractor like Cut Price Fencing.

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