How to treat wood with borax

Written by francis walsh
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Pressure treated lumber for outdoor construction is what most of us recognise as a piece of treated wood. The procedure infuses a compound into the wood fibres to slow decay and make our decks last longer. You can also treat wood with Borax though, a less commonly known way to cure wood with high water content, inhibit fire, and keep wood rotting insects away. Borax is a water soluble mineral that you can treat a number of products, including for use in the building industries.

Skill level:

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Things you need

  • Freshly cut wood
  • Water (2.5+ gallons)
  • Borax (284gr)
  • Sprayer (pump type)
  • Barrier protection (tarp/cloth)

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  1. 1

    Lay a protective barrier around the wood parts to be treated. The Borax solution can leach out onto the ground and can poison some types of grasses. Prevent Borax overdose to plants and animals by preparing a quality work area with the protection of an edge guard or with towels to catch any run-off of Borax solution.

  2. 2

    Arrange the raw wood so that each side can be treated with the Borax solution. Check that you are able to flip the pieces on edge and over onto the other side to get an even coverage of Borax onto the wood boards. Take the pump sprayer and the Borax to a water supply and mix up a batch of Borax wood treatment.

  3. 3

    Dissolve 284gr of Borax (20 Mule Team variety) into about 177ml of warm water. Agitate the solution until the Borax is dissolved. Pour this mixture into 1 gallon of plain tap water and mix so that it too is blended well. Now pour the treated gallon of water into the hand pump sprayer and tighten the cap of the sprayer. Pump it up to pressurise the inside.

  4. 4

    Spray the solution evenly onto each side of the raw wood boards. A Borax component within the wood means this wood will be effective at repelling pest animals, inhibiting fire and curing faster by being treated with a simple Borax and water solution. Spray one side and then turn on edge and spray the edge, and turn and spray the back, and turn and spray the edge. That covers the entire board. Continue to spray boards until the solution is used. A gallon of solution will treat about fifty 2"X4"X8' studs.

  5. 5

    Cure the wood as you would normally. It can be kiln or air dried until the moisture content reaches. Determine the correct moisture content for your area and dry the wood until it has the recommended amount of water in the fibre. Install the wood as you would any other type of treated wood.

Tips and warnings

  • A more diluted solution will work the same for a shorter period of time. Borax can age wood's appearance. Avoid the ageing by using a diluted solution. Borax can accelerate the curing time for fresh wood to dry. When kiln-drying treated wood, be sure not to over dry by using a standard method of measuring curing time.
  • Borax is a poison at concentrated levels. Pets, children and adults can have adverse reactions to the ingestion of the Borax solution. Call a poison hotline immediately following and ingestion event. A veterinarian should be called if a pet is affected.

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