Hi @Andrew1964,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
When sealing exterior veneer doors, two of the most common options are varnish and oil. Both protect against the elements while helping to preserve the natural beauty of the wood, but they do so in different ways. The main decision comes down to whether you prefer a harder, longer-lasting film that requires less frequent attention, or a softer, more natural finish that is easier to maintain but needs reapplication more often. Choosing between a satin or matt finish within either option allows you to keep the timber looking authentic without a glossy shine.
Varnish is the stronger and more durable option, forming a protective layer over the veneer that shields it from moisture, UV damage, and daily wear. The main advantages of varnish are its durability and the longer intervals between maintenance, often lasting several years before requiring attention. On the downside, it takes more effort to apply—usually several coats with sanding between—and once the surface begins to break down, refinishing typically involves sanding back to bare wood before re-coating.
Oil, by contrast, penetrates into the veneer rather than sitting on the surface, leaving a more natural look and feel. The key benefits are ease of application and maintenance, as oil finishes can be refreshed with a simple clean and reapplication rather than full sanding. However, they are less robust than varnishes and will need to be reapplied more regularly, usually every year or two, to keep the wood protected. This makes oil a good choice for those who value appearance and easy upkeep over maximum durability.
In terms of varnish, I would recommend Cabot's Matt Water Based Exterior Clear. For oil, I would recommend Intergrain Clear Universal Timber Oil.
With either option, you should make sure the door is well prepared prior to application. Give the full surface a sand with 120 grit sandpaper, brush it down to remove all sawdust, then sand again with 240 grit sandpaper, then brush again to remove sawdust.
Once sanded, apply your sealer in light coats with a foam roller, back rolling over everything to hide any seams created on application. Allow the sealer to dry for the advised recoat time, give it a light sand with your 240-grit sandpaper, and then apply a second coat, repeating the back rolling process.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
