There seems to be much confusion when it comes to the term Select Hardwood, so I figured a writeup that could be placed in the FAQ section wood be appropriate.
First of all, what does the term Select Hardwood mean? Does it refer to a particular species of wood? Does is imply that the headstock will have wings? The term Select Hardwood simply allows Martin to choose the neck wood based upon what is available at the time. Right now Martin is currently using Spanish Cedar and Mahogany as the two choices for neck wood. Certain models have been switched to Spanish Cedar on a regular basis. Right now the list is small; however, this list will grow as Martin sees fit in order to maintain production.
Other models are continuing to get Mahogany for the neck. Many of these models are also being built with Wings on the headstock. Wings will be explained later.
The main issue is that Mahogany is becoming quite scarce in the quantities and quality that Martin needs to continue using it on a regular basis. Spanish Cedar has proven to be a good replacement and in fact has been in use by Martin since around the year 2000. The 16 series guitars have been getting Spanish Cedar necks since that time.
Wings are another hot topic that many do not understand. Wings are simple to explain and pictures will be provided at the bottom of this post. Neck blocks come in different sizes. Larger blocks allow the neck to be built with out the need for wings. Smaller blocks, however, are simply not wide enough, so Wings are added to the headstock. Wings are the addition of small pieces of wood that makes the neck block wide enough. The wings are only visible from the back, and have no effect on tone. As Mahogany supplies continue to dwindle, the use of wings will become more and more prevalent. Wings are only being added to Mahogany necks at this time. Any guitar that gets a Spanish Cedar neck will not have wings, at least not at this time.
Regarding slotted headstocks, as of January, 2007 Martin will begin building the D-15S and the 000-15S models with a winged Mahogany neck. This type of headstock has been tested and Martin is happy with the results. The glue joints are on the outside of the slotted area and do not pose any stuctural issues. This change only affects the D-15S and the 000-15S at this time. All other slotted headtock models will not have wings, but this of course can change as Martin sees fit.
It should also be noted that Martin considers both Mahogany necks without wings and with wings to be solid Mahogany. Thus, any Custom order in which a Mahogany neck with no wings is desired needs to clearly indicate that fact.
Linda Davis-Wallen, aka CFMWoodbuyer on the forum, has been very gracious in answering questions regarding all of these issues. I asked Linda to provide an explanation to the technical terms regarding necks so we might better understand why wings have become necessary. Below is a direct quote from an e-mail she sent me regarding this.
Understand that most 12/4 (3) thick lumber is less than 3 thick after sawing and drying. Since the rest of the world works in metrics, most 3 lumber is cut at 75mm, which is just shy of a full 3 thickness, before the shrinkage due to moisture loss in the kiln drying process. That is perfectly acceptable for the world market and other industries, but not for a one piece guitar neck. We must actually start with lumber that is rough sawn and kiln dried that is no less than 3.015 thick in order to get a solid piece headstock at the top. So, that is our most limiting factor when purchasing suitable lumber. Then all the material that is quartersawn, has surface checking/splits, has wormholes, or has other defects must also be rejected for our use. As a result, we are only able to use about 5-15% of the material imported by our suppliers. Then there is the individual producing nations politics, and environmental issues (CITES, etc.) to deal with also."
That is also true of the 10/4 (2.5) flatsawn lumber that we need to produce necks with wings on the headstock. If that thickness varies, the wings will not fall in the right place on the headstock and/or we will not have enough thickness at the heel portion of the neck.
Linda has also stated that Martin is currently reserving whatever 12/4 lumber they are able to procure that meets Martins standards for the following models: 45s, GEs, and Authentics. It is important to note, however, that this list could change at any time.
It is also important to know that Martin is already looking at other woods for necks, as even Spanish Cedar is getting difficult to get in the quantities that Martin needs. This will be an interesting challenge for the Martin Guitar company, and only time will tell how they overcome this challenge.
As time goes on, we will try and keep this updated so we can at least know the status of neck woods at any given time. I hope this write up has been helpful.
I would like to thank Linda, aka CFMWoodbuyer for her input on this writeup. As always, she has been more than helpful.
Here are some illustrative pictures.
Mahogany vs. Spanish Cedar - Spanish Cedar on left, Mahogany on right:
Wings vs. No Wings: