Fading timber and the lightfastness of finishes are the elephants in the room. The Victorians had it all worked out, sunlight is damaging so get heavy velvet curtains and keep them drawn! But today we seem to expect to have our cake and eat it, we want huge windows and patio doors so our homes are washed in daylight, while at the same time we want either ultra pale timbers or gorgeously deep and dark highly figured grain.
Here are some tests that I ran,
Working clockwise from top left is Oak, Rippled Sycamore, Black Walnut, and Cherry. The right side of each board has a UV resistant finish, the bottom half was masked off, then they were put in a south facing window for just two months of a normal drizzly British summer!
Conclusions? Oak holds up fairly well to indoor sunlight (Sweet Chestnut is even better), Cherry darkens and acquires a lovely patina in short order (as do most fruitwoods, Swiss Pear for example is a dream), Black Walnut fades to a dull boring brown (English Walnut holds up a bit better, fading but acquiring some nice honey tones along the way), and Sycamore loses it's brightness very quickly (roll these tests on a few more months and Sycamore or Maple can end up a nasty shade of tangerine!).
What about UV resistant finishes? The really effective ones are designed for yacht applications and hold up well even in tropical sunlight, however they're not really appropriate for furniture use because even though they do a great job of blocking UV rays
initially, the active ingredient is actually broken down by sunlight, so after a few years it has almost no effect. That's not a problem for yachts as regular renewal is part of normal maintenance. But for furniture it means the practical options are much more limited. There are some extremely expensive spray only finishes that have been released recently, making big promises of stopping the yellowing of pale timbers, but they're not really practical for the small workshop. Osmo UV is probably the best of the remaining, not particularly good bunch, however it will yellow pale timbers immediately so has limited relevance for Sycamore or Maple, but isn't too bad on Walnut which many people prefer warmed up a bit with an amber tone.
I've posted recently about a fairly new staining product called Transtint that claims to offer improved lightfastness over traditional aniline dyes, you might be interested in reading that.
