In a world dominated by sleek metal structures and contemporary designs, there’s something undeniably enchanting about the timeless charm of wood and the qualities of wood preservation. Whether it’s a rustic cabin nestled in the woods or an elegant antique piece handed down through generations, wood holds an irreplaceable place in our hearts and homes. Yet, despite its natural beauty and inherent strength, wood is susceptible to the relentless forces of time, weather, and pests.

Enter wood preservation, an age-old practice that aims to safeguard the beauty and integrity of this precious resource for generations to come. From ancient civilizations using tar and oils to modern scientific advancements, the art of wood preservation has evolved significantly, but its essence remains the same: to enhance wood’s natural resistance and prolong its life.

In this blog, we embark on a journey to unravel the secrets of timber preservation and learn how to preserve our cherished wood possessions effectively.

1. The hazard defined

Wood Preservation is so vital whenever you are working with wood.

There are various factors that can contribute to the deterioration of your wood.

While you are able to use untreated timber for various structures, you are risking the structural integrity of your building. This is because of the fact that there are various factors that contribute to the process of decay of your timber.

This is especially important if you are planning on building any type of structure inside or outside of the house. As a buyer or seller of wood, you need to be aware of these factors in order to prevent them.

We firmly believe in buying SABS Approved CCA Treated Timber for any and all construction projects.

Here are some of the factors that contribute to the deterioration of wood:

• Fungal Decay
• Wood borers
• Termites
• Crustacea
• Weathering

Read more on the deterioration of wood here. 

2. Wood preservation Chemicals

Wood Preservation is one of the most important things to consider when working with any type of wood. As a result of the many applications for wood, there are various treatment methods for wood preservation. These methods all have different chemicals, with different pros and cons.

Therefore, in this post, we will explore the methods so you can make an informed decision when purchasing timber for your application.

3. Borate Compounds in wood preservation

Boric acid, oxides, and salts (borates) are effective wood preservatives and are supplied under numerous brand names throughout the world. – Wikipedia

This wood preservation method is of low toxicity to humans. Therefore, the wood will leach into the ground and water when the surface comes in contact with moisture. As soon as the chemicals in the wood start leaching, the effectiveness of the wood treatment is compromised. This means that the timber will be vulnerable to attack from fungi, insects and more.

The borate compound is more effective when used with soft woods with high moisture content. There are different factors that contribute to the effectiveness of treatment like surrounding temperature, borate concentration, number of treatments applied and, wood species. Therefore, it is suitable for woods like Pine. Hardwood timber preservation is usually treated with other timber treatment methods like CCA.

Pros of using Borate Compound for Wood Preservation:

• Kills wood-destroying insects
• Bacteriocide/fungicide to control “dry rot”
• Anticorrosive in some formulations
• Fire retardant in some wood applications depending on borate loading and type used
• Low Toxicity to humans

Courtesy of American Borate

Cons of using Borate Compound as Wood Preservation Chemical:

• Is not fixated in the wood.
• Vulnerable to leaching
• Effectiveness reduces over time
• More suitable to softwoods like Pine
• Cannot be used in water or in-ground
• Cannot be exposed to moisture

4. CCA (Copper Chrome Arsenic) Treatment for Wood Preservation

CCA Treatment is one of the most popular ways of treating timber due to the effectiveness and low maintenance.

As can be derived from the name, CCA is a mixture of Copper, Chrome and, Arsenic. This chemical compound is then fixated into the wood by a high-pressure system.

CCA wood preservation Process

The process of treating timber starts with putting dry timber into the pressure vessel, the chemicals (CCA – Chromate Copper Arsenate) which have been dissolved in water are then pumped into the dry wood at a high pressure. Thereafter it is left to dryThe wood stays in the high-pressure vessel for a while to ensure that the wood soaks up as much as it needs to. Each chemical has a specific goal:

“The chromium acts as a chemical fixing agent and has little or no preserving properties; it helps the other chemicals to fix in the timber, binding them through chemical complexes to the wood’s cellulose and lignin. The copper acts primarily to protect the wood against decay, fungi, and bacteria, while the arsenic is the main insecticidal component of CCA, providing protection from wood attacking insects including termites and marine borers. It also improves the weather-resistance of treated timber and may assist paint adherence in the long term”

After the treated timber has dried, it is safe to use immediately. The whole CCA treatment process takes 1 – 2 days (excl drying times).

Read up regarding other questions regarding CCA Treatment for Wood Preservation:

• CCA Treatment Dangers
• Do they still sell CCA?
• How to dispose of CCA 
• Which Treatment Class to use for my application

Pros of using CCA Treatment for Wood Preservation:

• Has a minimum 15-year guarantee when buying at @SabiePoles
• Requires no maintenance
• Suitable for various uses above and in the ground.
• Different treatment classes, depending on the application of your timber
• Does not leach into the ground
• Safe for use in and outside of the house
• Suitable for both hardwoods like eucalyptus and softwoods like pine
• Fixated in the wood
• Affordable in South Africa

Cons of using CCA Treatment for Wood Preservation:

• Slight effect on strength and dimension wood properties
• Slight effect on wood corrosiveness
• Courtesy of SAWPA

5. Alternative to CCA

There are so many alternatives to CCA Treatment but all of them come with their own pros and cons. We have extracted a brief table from The Univesity of Wollongong to showcase the main properties of the other wood preservation chemicals and methods:

There are several alternative chemicals being promoted as alternatives to CCA, as listed in the table below. None of the available alternatives is a complete substitute on its own for all the uses of CCA and, although they do not involve arsenic or chrome, they still pose environmental and health risks. – The Univesity of Wollongong

6. Oilborne Preservation

According to SAWPA,  the only oil-borne preservative which has been used in South Africa, is creosote and mixtures of creosote and coal tar solutions, with or without a waxy oil additive. Oil-borne preservatives are applied in hot and cold open baths or in vacuum-pressure impregnation plants, always at elevated temperatures to lessen viscosity and increase uptake.

In one of our previous posts, we discussed the pros and cons of CCA vs. Creosote. You can head on over and check out the benefits of and disadvantages of using Creosote. 

7. LOSP (Light Organic Solvent Preservation)

LOSP  is a waterproof timber treatment.  This treatment is applied by vacuum pressure impregnation. Additionally, you can include wax to make the timber water-resistant.

“Depending on their type and formulation, they may be suitable for interior or for the exterior, above-ground hazards such as in housing and other buildings. Effective preservative treatment of wood can only be achieved by impregnation in a vacuum pressure plant.” – SAWPA

8. Antisapstains

Antisapstains are temporary treatments to temporarily protect wood against mold and fungi. Usually applied by painting or spraying the wood with the preservative chemical/treatment.

9. Penetration and Retention

The rate of penetration and retention differs greatly depending on which treatment option you choose to make use of.

The penetration refers to the depth at which the chemicals enter the wood. The depth of penetration is dependent on the cut and species of the wood being treated. Additionally, the deeper the treatment penetrates, the more effective and long-lasting the preservative treatment will be.

Retention, usually expressed as kilograms of preservative per cubic meter of wood (pounds per cubic foot), is the amount of preservative retained in the wood after completion of the treatments and is one measure of the degree of protection provided.

Asking the right Questions when purchasing from a Treated Timber Supplier

Whether you are buying from a wholesaler to resell in your hardware store, or a contractor buying treated timber for construction purposes right through to be an individual just buying a few treated poles for your backyard. There are two things you need to ensure before you purchase your wood:

1. Is the timber SABS approved?
2. Does the timber adhere to NRCS standards?

If the answers to these questions are “No”, we strongly advise that you search for a different supplier.

In conclusion, while there are many factors contributing to the deterioration of wood, there are many preventative measures for the preservation of wood. We explored many different preservative chemicals, their pros, and cons, and left you with a final warning regarding the standards and regulations of treatments. We hope that this post has given you the answers you were looking for!