How to oil a timber fence to stop mould?

FionaJS

Hello, 

I had treated sawn pine timber fences put up 6 months ago. They started getting mouldy within a few months. I have high pressure hosed them but they are still dark in many places?? Is this normal?

I would like to paint with timber oil but not sure which one to choose?

I would like a clear oil, one that will resist mould, doesn’t require me to apply a cleaning solution first and needs only one coat. Do my fences look ok to put oil on? 
Thank you so much, any help would be greatly appreciated. 

EricL

Hello @FionaJS 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about oiling your timber fence.

When you have fresh timber paling installed it usually takes 6 to 12 weeks to weather it. During this time any tannins, oils or surface treatment usually gets washed away by the weather. At this point in time after the 12 weeks the fence should be oil, stained or painted. Failing to do this the fence will now proceed to the next stage which is surface aging. The unprotected surface of the paling will start to deteriorate into that silver grey patina, and mould will start to anchor onto the surface of the paling. But this is just on the surface, internally the pine is protected with a chemical treatment.

Pressure washing will sometimes help but if the surface of the timber has started to turn dark this is a sign that there is a layer of dead timber cells on top. In order to get rid of this it will be necessary to use Cabot's 1L Deck Clean - 1L in combination with a scrub brush. I'm aware that you are not keen on applying a cleaning solution, but this is the only way to remove those dark sections of your fence paling. If you oil it now those dark sections will not be covered by the oil and will remain dark. Even if you were to use a dark oil you will have sections of your fence with dark patches in them. 

Since your paling fence is properly weathered, I propose taking that extra step of cleaning to revive the paling fence back to a brighter finish. I suggest looking at the Cabot's 4L Aquadeck Natural Exterior Decking Oil, and the Intergrain 4L Clear Nature's Timber Oil. I recommend testing the oil on a small section of your fence so that you can see what the finish will be like. If you are happy with how it turns out, you can then commit the entire fence.

If you need further assistance, please let us know.

Eric