Pros and Cons of Creosote and CCA
SAWPA draws no distinction between the wood preserving properties of Creosote and CCA. Both are able to effectively protect wood from attack by fungi and insects. They are however very different in their form.
Creosote is a black oily substance whilst CCA is a water-borne treatment.
A comparison of the important properties of each preservative is given below:
| PROPERTY |
CREOSOTE
|
CCA
|
|
| Efficacy |
Fungi Termites Wood-borers Marine borers |
Good Good Good Good |
Good Good Good Good |
|
Permanence (Preservative losses) |
Bleeding Leaching Evaporation |
Fair Slight Slight |
None None None |
| Penetration |
Good
|
Good
|
|
| Effect on wood properties |
Strength Dimensions Flammability Corrosiveness Paintability Gluability Colour Odour Cleanliness |
None None Slight None Poor Poor Dark Strong Oily |
Slight Slight None ¹ Slight ² Good ³ Good ³ Light Green None Good |
| Toxicity |
High
|
High 4
|
|
| Water Repellency |
Good
|
None 5
|
1. Timber treated with CCA may be damaged by intensive veldfires as a result of its susceptibility to ‘afterglow.'
2. CCA-treated timber should be left for at least seven days after treatment before fixing metal fasteners or fittings.
3. Except where the preservative formulation contains a water-repellent system such as wax or waxy oil which may have a detrimental effect on the paintability and gluability of the treated timber.
4. Once it has completely reacted with the wood constituents, CCA-treated timber is completely safe to use and handle.
5. Water repellency may be introduced with the inclusion of a wax/oil additive.
Article sourced from the SAWPA website: http://www.sawpa.org.za/ with their full knowledge and permission.