I don't have much experience with Jatoba, but what you're describing is unlikely to have anything to do with "drying out."

Lacking a picture, I'm wondering whether you've got some sapwood in your moldings.

Thanks Jon. That is quite plausible, as it is not throughout the wood, just some sections. The photos I took last night didn't turn out so I tried again this morning. I still can't quite capture the extent to which the streaks differ. The darker ones are noticeably oily while the lighter ones are dry to the extent that the grain even feels rougher.

My photo of the better parts is not in focus so will work on another, but it has a very even colour.

Thanks again,

KarinL

I just realized, with some chagrin, that I exacerbated this problem. I remember that when dry streaks first began to show up on the wood I wanted to see if some oil would help and I put some non-drying oil on one of the dry streaks to see what would happen. I am guessing that that oil has worked its way through the wood in a way that is different from what wood like fir would do; here it has absorbed in streaks.

Adding this to a little on-line reading, I'm concluding this is not sapwood but that the wood does dry unevenly, and I should likely have sealed it when I bought it, front and back. I may be lucky that it has not yet checked or split. But as we have had unfinished fir and poplar mouldings around for decades, and sundry pieces of walnut and other species, it didn't occur to me to be cautious about how I stored this wood.

So now I guess that I have unevenly-dried or overly-dried wood with some oil streaks. Should I even out the oil, and if so, would an oil that hardens be a good idea? Or should I just clear coat as is and count my blessings? I'm thinking either option would even out the appearance, but which would keep the wood the most stable?

KarinL

I'm still confident that you're on the wrong track with ideas that the wood has dried unevenly. A meter would show you that the moisture content is consistent across the board, not varying in stripes. That moisture content will fluctuate slightly with changes in humidity, but the wood is neither over-dried nor unevenly dried.

Jatoba is rather unstable so sealing all surfaces would have some benefit, especially for wide boards. To improve stability, you'd need a film finish like varnish, polyurethane or acrylic (Some "oil" finishes are really just thinned varnish). It's overkill to think you need to do that just to store the stuff. Even without such treatment, the instability is unlikely to be a problem on narrow moldings used indoors.

I think what you're seeing (the uneven coloring) is perfectly normal for this wood, exaggerated by the oil you applied. If you do a Google image search for Jatoba you'll see lots of pictures of stripey wood. It doesn't look nice and even like cherry because it's not cherry.