Unusual Pink Ivory color change examined 

Updated 8/10/2007

Pink Ivory (Berchemia zeyheri) comes from a relatively small South-East African tree.  This heavy and beautiful wood was considered extremely rare at one time, and still commands a high price.  The loss of color in dark-dry storage is a serious problem.  I have listed and described a number of cases of color changes below. 

In living trees, the cells in the outer rings of the tree that conduct water upward (sapwood), are nearly white in color.  As the sapwood ages, the wood changes from sapwood to heartwood.  At this time, the wood usually undergoes a rapid change in color (In some tree species, the heartwood stays white). 

In Pink Ivory the color change is much more gradual than in most species.  In Pink Ivory, the white eventually changes to light pink, then pink, reddish, and a finally a full deep red color. 

It is a well known fact that in nearly every colored wood, exposure to light will cause the colored heartwood to loose color; however Pink Ivory also loses color away from light (and under low moisture conditions) in ways that are not typical. 

I noticed some eBay sellers labeling the discolored wood as sapwood.  As a professional Wood Scientist, I felt this error needed to be addressed.  The specimens shown are from my personal collection.  I have many pieces of Pink Ivory in my collection, with some pieces having been in my collection for over 30 years, and only show minor changes, while some that I have had less than 3 years are practically brown and nearly colorless when sanded. 

In the lower left image below, there is shown a piece of Pink Ivory with internal damage to the living tree (bottom left photograph) which has allowed air and microorganisms to have access to this recessed area.  The change in color was present before light was able to penetrate this region.  This would suggest either oxidation or a microorganism at work.  The small worm holes in the 2nd piece again show where entry of an organism caused color change (the top of the 2nd piece is lightly sanded). 

The left sample of the group of three is an end view, and shows color change that follows the growth rings in this specimen.  In this set of three, note the great variation of color change from piece to piece (all surfaces sanded in this group).

Both pieces in the group of two were the same color when received as a single lot, have been stored 3 years, and show great difference when partially sanded.

The rippled board was a beautiful watermelon red when finished in multiple coats of gloss polyurethane on one surface less than two years ago.  (This photo is as close to the actual current color as I can manage).  The unfinished side has changed color like the finished side.

Conclusion:  Light is not responsible for the color changes in these pieces, and neither is oxygen, as the outsides of some are deep red while the center color varies.  The color change has followed the growth rings in some cases.

Chemistry of this wood does vary when near the growth ring boundary between sapwood and heartwood, as evidenced by the gradual color change mentioned above.  The reasonable conclusion is that chemical changes within the wood have created the significant color change.  Microorganisims have accelerated these changes since they alter the chemistry of the wood.

Recommendation:  Do not store this wood for long periods of time before you make your project from it.  The surface has been the most consistent color retaining part of the wood in my storage, with color changes often not appearing until the wood was sanded.  If possible, use the wood soon after purchase.  Use wood from near the center of the tree, which tends to have a darker color (but always avoid the pith).  Do not store the wood in strong light, especially sunlight. 

If this information was interesting or helpful to you, please take a second to give me credit.  Thank You!  Scotty Drye