What is ‘Leaching’ and how do I remove it?

Are you wondering what the brown stains on your concrete around your newly installed outdoor furniture are? Are you worried that you may not be able to remove them? 

Don’t panic! Timber leaching is a completely natural process and is almost guaranteed to occur when you first purchase a natural timber product and expose it to the elements. Leaching occurs when moisture enters the timber cells via the cut slat ends, causing tannins and extractants to be released from the timber. This causes a brownish, rusty looking stain to bleed onto nearby surfaces (such as render, concrete or pavers). Merbau Hardwood is especially susceptible to bleeding because of its high tannin content.

To limit leaching stains, we suggest that you water blast or high pressure hose your wood product thoroughly (2-3 times) before it is installed in its final position. Do this on a grass or soil area, to ensure the tannins are not released onto the concrete/pavers. If you wish, there are protective coatings available that can be used to seal off the timber and further limit leaching.

To remove leaching stains that have already occurred, we suggest you immediately scrub the area with water using a stiff bristle scrubbing brush, then scrub the area again with undiluted vinegar or bleach. Allow the substance to soak into the surface for 20 minutes, and then wash off with clean water.

As the timber weathers, the leaching is likely to reduce. But as we said before, don’t worry because it is a completely natural occurrence!

We hope that answers your question and trust you are able to remove your unwanted leaching marks! 

If you need more information, you can read more HERE.