How to oil an old pergola?

[minhletn]

 Hi everyone,

Our 7 years old pergola got mouldy on the parts that exposed to sun and rain so I cleaned it up using https://www.bunnings.com.au/30-seconds-1l-outdoor-cleaner-spray-1l_p4461747 and a brush and got it back to this

Once it dried up, I put a coat of Digger oil anti-mould (https://www.bunnings.com.au/diggers-1l-ready-to-use-anti-mould-formulation-timber-oil-1l_p1670041) but it now has a grey weathered look

Not sure if I did something wrong

I want to have a natural timber colour as other parts, which is why I went with oil

Should I use stain or a different timber oil instead?

the parts that didn’t have mould are dirty and have some water stains, so my plan was to wash them up and oil them as well

Thanks

[JacobZ]

Hi @minhletn,

Thank you for your question about oiling the timber structure of your pergola.

The issue you are experiencing is due to the fact the outer layers of the timber are weathered. Cleaning them is a good first step, but unfortunately, it is not enough to completely remove the weathered look of the timber.

To get the best results with oils you will need to sand back the timber to remove the weathered outer layer of timber. 

I'd suggest due to the large amount of timber, you will need a belt sander or random orbital sander to speed up the process.

You will need to start with a heavy grit, such as 40 grit to remove the weathered outer layer, followed by 80 and then 120 grit to get a nice smooth finish. Once sanded, you will need to brush down and clean the timber to remove any saw dust present before reapplying your oil following the manufacturer's instructions.

Let me know what you think and if you have any further questions, please don't hesitate to ask.

Jacob

[minhletn]

Thanks @JacobZ,

It looked okay (not grey) after clean so I thought I couldn’t get away without sanding. Will try again with a sander

Do you think these parts need to be sanded as well or cleaning would be enough?

Thanks,

[EricL]

Hello @minhletn 

I recommend sanding all of the timber so that everything will be ready for oiling. If you skip one portion of the pergola and its surface happens to have dried off and petrified no amount of oil will permeate its surface and it will just curl back on itself and not get absorbed by the timber. You'll then need to sand its surface to remove the old surface timber. 

If you need further assistance, please let us know.

Eric