[IgorPartola]

Do those oils polymerize at that temperature and are those polymers food safe? Also how stable are they since spatulas routinely come into contact with high temperatures?

I honestly do not know because while I have read that specifically boiled linseed oil does cure to be safe it was not clear to me whether it was safe for skin contact or fully food safe and food safe isn’t the same thing as safe for e.g. stirring pasta as it boils or stirring food that is frying in oil.

[bluGill]

Boiled linseed oil is because the additives make it look like boiling - this contradicts the article but I believe the article is wrong. One of the traditional additives was lead, but even the modern lead free versions are not all that safe for food unless the manufacture claims otherwise (most don't)

[Doxin]

You can still get actual "proper" double boiled linseed oil. It's not even especially expensive, just mildly annoying to source. It's a surprisingly durable finish for outdoor furniture etc, just takes an age to cure compared to the chemically boiled linseed oil.