Specifically I am wondering about polyurethane (Rustoleum Ultimate) over boiled linseed oil, but in general polyurethane or other top coats with similar chemistry over any drying oil.
Question is: Can I apply polyurethane over an oil before the oil completely cures or do I have to wait?
I looked up linseed oil on Wikipedia and it led me to drying oils. These oils polymerize by reacting with ambient O2. I also attempted to research the curing process of polyurethane but discovered there are many different types with many different uses, so it was difficult to find info. I think they cure by reacting with ambient moisture.
My knowledge of chemistry is too limited to be able to understand if polyurethane would allow O2 to pass through to react with the undercoating of oil as it cures.
The other random bit of info that I found is that Rustoleum Ultimate polyurethane primarily consists of:
Neither of which I understand. I reached the conclusion that they are moisture cured from this article although it concerned types of polyurethane used on metal. Not sure if it's the same as wood.
So, can I apply polyurethane before the BLO cures? Will it continue curing underneath? Or do I have to wait? If I do have to wait, what will happen if I don't? Is it different for an oil-based polyurethane (it looks like the Rustoleum one is water-based)?