On Jun 24, 10:40*pm, "Leon" wrote:
"Tanus" wrote in ...

Walnut will lighten? Does that work the same way as cherry darkens? Make
sure it gets sun exposure and leave it there to lighten up.

Yes



I have a walnut bowl that seems a bit dark and if all I have to do is put
it by a southern exposed window, I'd like to see how light it gets.

I don't think it will lighten quite as quickly as the cherry darkens in
light exposure.

Here is a link to a Japanese book (“Wood and Cellulosic Chemistry” by
David N.-S. Hon, Nobuo Shiraishi)
http://tinyurl.com/knpd6f

According to the book, there are many causes of discoloration:
chemical, biological and physical. Results for light-induced
discoloration is shown in Table 7 for 100 species of wood (but Google
shows only part of the table) Positive numbers show woods that
darken and negative numbers show woods that lighten.

According to the Table 7, American walnut should lighten, but window
glass will block UV from sunlight, so it may take much longer than if
left in full sunlight outdoors.