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Originally Posted by David Clemons
. . . from what I've read drying oils do expand, possibly as much as 15-25% as they absorb oxygen . . .
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Try this experiment. Put just enough linseed oil in a palette cup to cover the bottom of the cup, and "pull up" visibly on the sides (that would be about 1/16" "deep"). Leave it in a warm, well-ventilated place (plenty of oxygen). At what point do you note expansion of the volume of oil by as much as 10%? What is the nature of the surface of the dry oil film as soon as the puddle of oil "skins over" ? Is it bloated, like a little bubble because of the volume of oxygen being absorbed, or does it resemble a raisin, shrinking in the sun from the loss of its liquid components through evaporation?
When linseed oil is heated to approx 475F in a vacuum in making stand oil, there is a
slight noticeable increase in volume, as the purpose is to partially polymerize the oil, which requires the addition of oxygen, but that's not a dry film state.