My approach is to crumble the alkanet in surgical alcohol and leave to to steep. Surgical alcohol is color neutral, whereas denatured alcohol will darken wood. Using the red alcohol gives me control of just how red I want to go.

For oil I opt for artist grade pure oil, no driers, applied in the thinnest coats. Linseed dries in contact with air, so a thick coat will take a long time drying, and in some cases it might not dry at all.

The method is here www.linseedoilfinish.com

Since linseed and other soaking oils do not give much protection from the elements the method starts with deep sealing with varnish, and it works.