I’ve got an oak beam to fit as a mantel above my new woodburner. This has been adzed to have a waney edge finish, but the wood on this edge is unfinished. I’m going to sand it smooth, but will then need to apply a finish.

Oil, varnish, or any other better suggestions?

Clear or coloured finish?

I would use osmo

Probably the woodwax finish. I would avoid varnish, at least when the wax/oil dries out it’s easy to refresh it.

At the moment it is natural, but I am contemplating a darker colour.

Tung oil can give a good finish to oak.

I would leave it natural. It’ll get bloomin’ hot above a stove and I’m not sure what would happen to the oil.

Danish oil – as many coats as you need to get it to the darkness you prefer.

I am with globalti, I would leave it natural and watch it age

That’s what I did with mine 😉

Danish oil will protect it. Varnish would crack under the heat.

2 or 3 coats of oil would give it a deeper golden colour.

At the moment it is natural, but I am contemplating a darker colour.

Then leave it natural for the moment. It won’t come to any harm, and you will be able to darken it with Rustins mid oak woodstain should you decide to hurry the darkening process along.

Definitely DON’T varnish it. It’ll look cack.

Oil, if anything. I can understand the desire to have something on there, against candles and glass rings.

I’ve had success with Fiddes and Osmo products. Don’t skimp. A little bottle of Fiddes is about £12 from Amazon. We use Oak Lightening to keep a natural colour.

We’ve achieved a pretty good, natural finish with Aglaia Hard Resin Oil. It really brings out the natural colours in the oak without, as suburbanreuben rightly puts it, making it look “cack”!

Chap I work with out an oak beam in as a mantelpiece when he rebuilt his cottage, used a chainsaw to get the rough shape, an adze to get it more or less smooth, then lots of beeswax over the years.
Personally I’m not in favour of staining oak when used in such a situation, I’d much rather let the wood age naturally and darken over the years as a natural process.

I’d agree with the wax.
I bought an old beam in November, asked the seller (who specializes in them) what varnish, he said never varnish them, just clean them up with a wire brush / water/ jet wash, once dry, use wax.

Careful with wax on an open-grained timber such as Oak. If you use a clear wax, it’ll sometimes sit in the grain and pores and look…..well, look like the pores are full of wax.
Use a wax of a similar colour, perhaps slightly darker.
Using wax around a fireplace doesn’t seem ideal to me as it’ll soften with the heat though I suppose it’s not a big issue on a lintel.

Danish oil is my finish of choice. Very easy to apply, keeps the wood looking gorgeous and natural. Wax can always be applied over the top of oil too once hardened off.

Lots of options – thanks. Im erring towards leaving it natural for starters.