Unless you are using spray, consider taping off sections on the inside of the base and experiment with different finishes.
Inside can be a bit of a rougher finish so might need some extra work on smoothing to get an idea of how the outside will look, especially if using dye or stain.
I like to dye or stain the wood before finishing to fit in with current decor but care is needed as Alder is a soft hardwood and can have uneven absorption of the colour.
Can still top coat over dye or stain but here are further considerations around oil or water based, plenty on YouTube but it can get confusing.
That's why I now test on the inside before trying a new finish.
To get over the potential uneven absorption of alder, I tried a tinted beeswax the other day and really liked the finish - lovely satin smooth finish. Haven't tried clear but would expect similar outcome.
Have tried tinted varnish but it can hide the grain if too dark. Tinted beeswax did not seem to suffer from this.
I have had good results with dye and poly but note the comment above about uneveness which can still look good (to me) with a deep gloss finish but depends what you like.
I'm determined to give french polish a go at some point but am working my way through the easier options first.
