As Margana of Inkophile mentioned numbers of pens inked could be reflective of season, I usually honor the seasonal change with ink choices. The first color that comes to mind for autumn color is Iroshizuku Fuyu-gaki, the Winter Persimmon. The warming feeling of the color not only because of its shade, but also derives from its intensity. For the several Iroshizuku ink I have tried, Fuyu-gaki is by far the most saturated one, but less shading as well.
Fuyu-gaki, when I first glanced at it, appeared orange, but now as I look more closely it is essentially an orange red, close to some shades of vermillion. Too bad I no longer have Caran d’Ache Saffron for a side-by-side comparison with Fuyu-gaki, since the two seem to share similar ratio of orange and red, but leaning toward red.
I have done the swatches a bit differently in this post. Instead of using a Q-tip, I did the swatches with a round watercolor brush. I repeated the stroke couple times at the beginning of the squiggly line to represent how the ink is in more concentrated form, and finish the rest of the line in one passing. Let me know how you like this new method!
Which ink do you turn to when the seasons change?