John K Jordan
12-01-2018, 8:47 AM
If you get the AAW emails you may have already seen this, in the email that came a few days ago. (If not an AAW member, it's worthwhile joining.)
397784
attributed to Alan Miotke, Mount Prospect, IL
This test seems a bit extreme since we seldom store woodturnings in direct sunlight (to avoid any bleaching), but I think it's interesting all the same.
My experience is close to this photo except most of the Jatoba I've turned started out darker than that in the test and hasn't changed much (yet). I've seen Padauk turn very dark like that; I quit using it. Osage Orange is not in the test but what I've used starts out very yellow but turns a much darker orangish brown quickly. And as most know, the red in Box Elder fades very quickly in the light, a little slower in a darker environment.
This test doesn't address if any color change is due to oxidation. I have some old Cocobolo and while the inside is beautiful with color the outside is dark brown all the way around, almost black, and extends a bit into the wood. It's hard to know how much of that is darkening is from light, from air, or from something else completely but based on the photo above I suspect it's not the light. In normal conditions out of the sunlight, the Cocobolo loses the beautiful oranges and reds and slowly turns darker.
I think a better test would compare similar pieces:
- in air with no light,
- in light with no oxygen,
- in air+sunlight,
- and in a normal environment - inside the house on the shelf out of the sun!
Control pieces should be kept in a dark chamber with inert gas.
An even better test would include pieces of the same wood covered with various finishes exposed to the same environments. Maybe if I find myself with nothing to do one day...
For those interested in color change and how to prevent it, this is worth reading. I has a nice list. The article discusses exotics but much applies to domestics.
https://www.wood-database.com/wood-articles/preventing-color-changes-in-exotic-woods/
JKJ
397784
attributed to Alan Miotke, Mount Prospect, IL
This test seems a bit extreme since we seldom store woodturnings in direct sunlight (to avoid any bleaching), but I think it's interesting all the same.
My experience is close to this photo except most of the Jatoba I've turned started out darker than that in the test and hasn't changed much (yet). I've seen Padauk turn very dark like that; I quit using it. Osage Orange is not in the test but what I've used starts out very yellow but turns a much darker orangish brown quickly. And as most know, the red in Box Elder fades very quickly in the light, a little slower in a darker environment.
This test doesn't address if any color change is due to oxidation. I have some old Cocobolo and while the inside is beautiful with color the outside is dark brown all the way around, almost black, and extends a bit into the wood. It's hard to know how much of that is darkening is from light, from air, or from something else completely but based on the photo above I suspect it's not the light. In normal conditions out of the sunlight, the Cocobolo loses the beautiful oranges and reds and slowly turns darker.
I think a better test would compare similar pieces:
- in air with no light,
- in light with no oxygen,
- in air+sunlight,
- and in a normal environment - inside the house on the shelf out of the sun!
Control pieces should be kept in a dark chamber with inert gas.
An even better test would include pieces of the same wood covered with various finishes exposed to the same environments. Maybe if I find myself with nothing to do one day...
For those interested in color change and how to prevent it, this is worth reading. I has a nice list. The article discusses exotics but much applies to domestics.
https://www.wood-database.com/wood-articles/preventing-color-changes-in-exotic-woods/
JKJ