So, I got to doing some finishing on a couple new pieces today. I figured I'd see how the walnut oil stacked up to linseed. For the test I happened to be working with some red oak, so I'll be commenting on comparisons based on previous experience with that and other "light" colored woods.
Most obvious is the viscosity. Walnut oil is much thinner and lighter than boiled linseed oil. In color the walnut oil is also significantly lighter. I could not tell where the walnut oil had begun to penetrate before rubbing it in with a cloth. Those who've worked with linseed oil will recognize that during initial application linseed oil has a tendency to show a marked difference from where it is initially flooded on compared to other settling points after it has been spread around.
Linseed oil tends to add a yellow hue to woods, which then moves into a darker amber with time. The walnut oil went on with just the slightest coloring of the wood, very gently bringing up the grain (as opposed to the *pop* that can occur with linseed).
The wood soaked up the walnut oil rather quickly. This is probably a combination of the thinness of the oil and the open pore nature of the wood in question. Still, the surface of the wood was not oily to the touch within 2 hours. It will have to wait until tomorrow to see if there are any distinct differences once the oil begins to cure.
For the next step, I'm going to do a side by side on two pieces of oak from the same board. After application and curing, I'm going to expose them to direct sunlight for a week to see if there is any difference to the colorization and surface texture.