Ask SAWS: What is that Wood?

That’s a question I often ask as I get another broken piece of furniture that needs a new part. It’s one thing to look at a new, freshly planed board and attach a name to the wood, but when the it has been stained, varnished, and in service for 50 or more years in sunny windows before one sees it, the challenge is somewhat greater.  I feel strongly about replacing furniture parts with the same species as the original if at all possible, so I’ve learned a few things over the years about what to look for.

My best teacher has been a book by R. Bruce Hoadley entitled “Identifying Wood”. In it he carefully explains how to inspect wood macroscopically (viewing with a 10-power eye loupe) as well as microscopically (using a microscope). Although Hoadley has a PhD in wood technology, he writes so that an amateur wood anatomist like me can understand it.

End grain test

When a broken spindle comes in, one of the first tools I reach for is a sharp knife – usually a utility knife with a new or almost new blade in it. I make a slicing cut across the end grain to expose cleanly cut end grain. I then examine it with my 10 X eye loupe.

The simple tools needed to view end grain - two types of eye loupe and a (sharp) utility knife

Almost every species has distinctive characteristics in its end grain and one needs to learn what to look for. It’s also important to have a reference to know what to look for. Hoadley has helpfully included high quality macro photos of most common North American woods, as well as the more commonly used exotics.

Many more pictures are available on an excellent website called “Insidewood” (https://insidewood.lib.ncsu.edu). I’ve also found it helpful to make known, labeled samples of as many species as possible. That way if I have a spindle that I suspect is birch, I slice its end grain, then compare it to my known sample of birch. If they match, I know I have a birch spindle to make. If not, I’ll pull out the maple known sample and repeat.

The key difference between birch and maple macroscopically is the ratio between the pore size and the ray width. Birch pores are clearly larger in width than the rays. In maple, the largest of the pores are barely equal in width to the largest rays, many are smaller. Most of the commonly used furniture woods that come my way can be identified this way.

End grain view of Paper Birch (Betula papyrifera) Note the narrow rays compared to the pore diameters.

End grain view of Sugar Maple (Acer saccharum) Note the much wider rays and smaller pores.

Collecting samples

Incidentally, this use of known samples has led me to collecting samples of any wood species I can get hold of – my collection of identified and labeled woods from around the world is approaching 700 different species of woody plants. Some are shrub woods; most are commercial lumber woods. Some are rare, others are very common. This, in turn, led me to join the International Wood Collectors Society (IWCS), of which a few other SAWS members are part of. As we sometimes swap samples, I’ve found this rather helpful in my collecting and identifying.

A year or two ago a fellow SAWS/ IWCS member emailed me that he had found a new wood being sold by Windsor Plywood call Gombé – did I want a sample? Of course I did, and part of the process of adding a sample to my collection includes examining the end grain as well as researching its scientific name. 

Several weeks later one of my regular refinishing clients stopped by with a couple of frame and panel doors that had shattered hinge side stiles – could I fix them? Normally this would be no problem, but these were an uncommon grain pattern stained an unusual purplish hue.

I looked carefully at the end grain – nothing recognizable there, but it seemed vaguely familiar. Eventually I thought of the Gombé sample, compared them and found a perfect match! Now all I needed to do was run over to Windsor, buy a board of the right cut and then replace the two shattered stiles. Assuming the refinisher got the staining shade correct, the doors should now be as good as new. Those doors are the only pieces made of Gombé (Didelotia letouzeyi) that I’ve ever run across in 38 years of woodworking and I was able to fix them thanks to a very timely gift of a sample!

My sample cabinets. Left hand drawers contain all the hardwoods. Top drawer on the right has all my softwoods, other drawers contain mystery woods, extra samples to trade, etc.

Other test options

There are times when an end grain examination isn’t enough to tell me what wood it is. That’s when I start slicing thin shavings off both radial (across the growth rings) and tangential (parallel to the growth rings) surfaces, putting them on a slide and peering at them through my microscope.

The International Association of Wood Anatomists has put together a list of 221 microscopic features to look for in a hardwood sample. Using the “Insidewood” website, I can enter some of these features and the site will check its database and hopefully come up with some possibilities. My success rate with this is not as high as I would like – I have a considerable selection of “mystery” woods that refuse to give up their identity.

Part of the problem is that many of these are taken from pallets and crates or foreign made furniture and those woods may not be in the database. “Insidewood” has 7,458 Modern Hardwood descriptions and 50,076 Modern Hardwood images (and counting). However, the best estimates I’ve read is that there are about 66,000 different woody species in the world. As well, my interpretation of a feature may not match that of the website.

Should you have a wood that is stumping you as to what it is, you are welcome to get a piece to me to look at. I don’t guarantee success, but I’ll have fun trying. And if your species isn’t in my collection yet, I may be asking for a 6” x 3” x ½” piece for me to label and catalog.

A glued up sample of a shrub wood - Korean Barberry (Berberis koreana)