In keeping with a Healthy House ethos I’ve tried to avoid the use of potentially hazardous or environmentally harmful products in the barn. When it came to wood preservative borax was the option that stood out.
What is borax?
Borax is the name given to several mineral compounds of the chemical element boron, namely sodium borate, disodium tetraborate and sodium tetraborate. Boron is a metalloid and so belongs the same family of chemical elements as silicon and arsenic. It has a diverse range of properties and is used in products ranging from detergents, through to cosmetics and as a food additive (E285 – it is a preservative and gives a firm rubbery texture to food!).
Of relevance us and this blog, in building applications, it is fire retardant, it is anti-fungal and an insecticide – ideal for treating previously untreated timbers in renovation projects.
It should be applied at a dilution of around 1 part borax to 10 parts water. It is best applied to a moist surface and will travel through the grain of the wood – several coats are recommended. If possible timber should be dipped in a weaker solution (around 1:20) and allowed to soak. Upon drying crystals of borax may form on the surface of the wood and can simply be wiped away.
It is worth noting, that while not acutely toxic, it can be detrimental to health. A significant dose is required to cause severe symptoms, but exposure can cause respiratory and / or skin irritation and ingestion may cause nausea, vomiting and abdominal pain. Handle with care and keep away from children. The EU has recently reclassified borax as a Substance of Very High Concern and as such it is no longer available as a general cleaning product. Despite this borax is still widely available – check Amazon or eBay as a start. I’ve personally used borax with my usual degree of care and despite it coming into contact with my skin, suffered no adverse consequences.
The green living tips website has an informative article and loads of comments discussing the many uses of borax.
I must admit to a slightly belt and braces approach to wood preservation on the barns external hardwood lintels as I’ve also treated them with a branded wood preservative – I just didn’t want to take any risks.