in the case of boiled linseed oil, the name's a bit of a misnomer. It's usually linseed oil cut with things like varnishes and/or solvents. It's not (AFAIK) actually boiled. I wonder if the term derived from older oil production techniques leaving some water content which, when boiled, was driven off to create a purer oil? Unlikely to be the case with your vegetable oil though.
That's a good suggestion, Leon. The big problem is that manual work here has zero status, and the tools and materials used are always dire. I'm getting blades from Brisa in Finland, and epoxy from Australia, so if I used some poor quality oil and made a mess of my new knives I'd cry like a baby!
Raw linseed oil is just that, straight pressed out of flax seeds and strained. It is edible and good to rub on wood. However, it will 'evaporate' (for want of a better word) to about half it's volume if left in the sun or gently brought to a boil. It's boiling piint is about 300 o C though so not something to be undertaken lightly and it will flash into flame if given half a chance too.
Boiled oil is a drying oil, it was the basis for many of the oil paints used in the past, because of this property. However, if boiled oil is left on a rag and that rag is discarded carelessly then the 'drying', which is really a kind of exothermic reaction may very well set the damn thing on fire.
I use boiled linseedoil and "Balsamterpentin" (sort of a refined version of plain turpentine) in a 50:50-mixture.
Insert the wood in the mixture for a week or longer (depending how patient you are) and then let it air-dry for at least a week. A mixture fatter than this will take ages to dry and the other way round gives not much protection to the wood.
Larger pieces of wood are placed on clingfilm, then doused with the stuff and carefully wrapped