In dealing with these species there is list of things to consider. First and foremost, reforestation (more to say about this later). Second, high on the list, wood preparation. A prevailing thought, even (shockingly) amongst wood resellers, that if a log yields a nice piece of wood it would be ready to be used to make a piece of furniture or such. Many variables influence the outcome of the final product. A piece of wood as beautiful as it can be is worth nothing until it is processed correctly. For the aforementioned reasons, we immersed ourselves and spent hundreds if not thousands of hours analyzing methodically, wood preparation, and its sustainability. We can now say that perfection will never be achieved but we can settle for great if not greatness and peace of mind.
An excellent example is what we experienced with Honduran rosewood, also known as Dalbergia Stevensonii.: The origin of Honduran rosewood is Mexico, Belize, Guatemala, El Salvador, and much less available in actual Honduras.
Wait a minute, Honduran means Honduras, right? Not precisely.
The upper area of Central America was formerly known as British Honduras which was composed of the five countries just named. One of the problems facing this area of the world is poverty. Like most other areas where this type of tree is plentiful, there are more lucrative businesses than lumber. For the landowners to realize a maximum profit from their properties, they have found themselves thinking of their trees as an object in the way of money.
The more cleared land they have, the better the opportunity for grazing for their valuable cattle or even creating desirable real estate for housing. So much of the best woods have succumbed to these circumstances. It is a widely accepted fact in that region that touching a Dalbergia tree for logging is illegal (which it is) so they turn to the next “best” thing… Cutting their trees down and to rid themselves of the “issue”, they burn the resulting “debris”. If you were to put a number on it, you would see that over 90% of the trees have vanished from their habitat in this manner. This has been the result of adding grazing land for cattle and new housing. Also, there is illegal logging where some people roll the dice, and through an illegal activity they can export containers of this material falsely identified as “cardboard” or “recycled electronics”. It has been an eye-opening experience.
So, the question arises, is there a sustainable way for man and forest to coexist?
The answer is yes; in a responsibly licensed harvest.
A lot of us have heard about Dalbergia trees being put into CITES Index I or Index II. The aforementioned problems are the reason why CITES has continually been creating these guidelines. In creating a responsible harvest license there is quite a lot involved. First, the forest is studied. Then a plan is created for eligible trees that can be harvested. All the trees in the lot are measured and accounted for. A certain diameter is allowed for harvesting depending on foliage coverage and the sex of the tree. A larger percentage of trees that bear seed is automatically prohibited from being cut down. These seeding trees are protected for more plentiful seed for natural reforestation to happen. A formula is created to figure out how many trees need to be replanted. If the forest is too dense, another lot is found that can take the new trees.
A forestry management engineer is in charge and recommends what is necessary to replace trees. Older trees are preferable for harvest for a few reasons. Growth of younger trees after harvesting will take about 2 to 3 years to make up foliage lost by the harvested trees. That is the natural occurrence from remaining trees beside the foliage of the new trees that were planted. All aspects of the resulting forest are actively monitored. These forests are not abandoned. Replanted trees are actively cared for so that survival is optimized. When neighbours see this activity, it discourages people from stealing trees from those lots. Another factor is forest tree thinning. Having a proper forest tree density is less likely to be a problem with fires. Fires in these parts of the world are a huge problem.
The bottom line is that if a consumer is buying wood that has the proper documentation, we are making sure that we are not being a part of a global problem. We can have clear consciences that we are doing something to address the deforestation so rampant in many parts of the world. Having said all of the above once in a while we have wood that has been in the United States since before.
Now that we have all of the above out of the way, we get to the next important inquiry. The number one wood preparation question is how well was the wood dried? There are many ways of drying wood. There is a ton of information online. The old school way of drying wood is air drying. There is a rule of thumb that for every inch of wood thickness it is 1 year of air drying. That is subjective because certain species may never get fully dried to the required moisture content. Equilibrium moisture content (EMC) in the location where the wood is being dried will likely be higher than where the end product will be used. One big drawback of air drying is the amount of time it takes before you can build with the wood. With air drying, you may have a 3” thick piece of wood that would have 20% moisture content (MC) in many pockets within the same piece of lumber. The next method uses a combination of air drying and conventional kiln drying (there are many different types of kilns).
We would not do this subject justice without writing volumes about it. That being said, most kiln operators do not dry wood immediately after harvesting. They usually wait 6 months to 1 year (some people prefer even longer). The advantage of kiln drying is that you can bring the MC (moisture content) down to a low level. If this kiln-dried piece of lumber is made into furniture and it is brought to Arizona, for example, where it is extremely dry, the piece of furniture is going to experience less physical change than if the wood had been air-dried. Wood moves with changes in moisture content. The problem with air drying and convention kiln drying is that you are still going to see damage to the wood. You may experience case hardening. This happens because as wood is being dried, the moisture that is present on the surface is the first to go. That means that the core of the lumber is still wet. You will notice this when working a piece of wood on a table saw. Case hardened wood binds your blade. The wood warps from internal tension. Other drying defects include external cracks call checks, internal cracks called honeycomb, cell collapse, and various other types of warp such as twist and crook. All of these defects together are called drying degrade. The amount of degrading from conventional kilns varies with equipment and operators.
We continued researching other kiln drying processes and started looking into the high-frequency vacuum kilns (RF/V). Particularly, we started looking at high-frequency kilns from overseas, VacuTherm, and PCS VacDry kilns. After much research, we were overwhelmed by the PCS VacDry kilns. They are expensive but there is a reason why. So what is the big deal about vacuum kiln drying? It is very complicated but once you understand it, it makes perfect and logical sense. We will do as best and brief explanation as we can. The main objective of drying wood is very obvious: Water removal. The big question is how to remove the water from without the wood being damaged during the process. Water is the main culprit of wood degradation when kiln drying. Two types of water are encapsulated in a freshly cut piece of wood. Free water and bound water. Free water is water that goes up and down the tree through microscopic channels resembling straws. This type of water is the easiest to remove from the wood, but it still has to be done with care. Bound water is water that is contained in all of the cells that compose the tree. It is chemically bound to the cellular structure of all the tree cells.
To break these bonds, you need a lot of energy. Almost like a balloon that doesn’t give up what is inside of it until it pops. That is when the problem happens. In PCS VacDry kilns you are not heating wood but you are providing energy to break bonds. With bonds broken, liquid water can become water vapor and the vapor can be moved out of and away from the wood. Cellular collapse can occur if the vapor is moved out to fast but the VacDry kilns have precise heating control. This precise control becomes precise drying control and collapse is prevented. Most conventional kilns dry wood between 120-190 degrees Fahrenheit. Even at those temperatures, it is amazing to think that you are not boiling water (water boils at 212 degrees). Conventional kilns can’t vaporize water deep within the wood. They dry with a humidity gradient. Warm air with a humidity level low enough to pick up water molecules from the wood surface is blown over the wood for days, weeks, or months. Just as with vacuum kilns, the free water will be gone and more energy (heat) is required. It’s a roll of the dice. Keeping the required temperature at the required humidity at the required airspeed as MC changes is a full-time job for operators running multiple kilns.
A vacuum kiln has a huge advantage because it can boil (vaporize) water at low temperate. How is that? When you have a load of wood inside of an airtight chamber, you can now lower the ambient pressure inside of the chamber. Realize that atmospheric pressure holds water molecules together as a liquid until the liquid water is heated to 212’F. Here’s why. Water molecules are always in motion and are bouncing away from each other. As the temperature increases, the amount of movement increases. Some molecules in the liquid are bounced away with enough force that the become water vapor. The combined force of these molecules that are being bounced away is called vapor pressure. When vapor pressure equals ambient pressure, water boils. Therefore, when you lower the ambient pressure you can vaporize water at a lower temperature. The other extremely important thing is that the vacuum also efficiently removes the vapor from the wood. When the water was converted from liquid to gas, it picked up heat that is now carried away. The result is that the temperature of the wood will be at the boiling point of water as long as free water is boiling away. Increasing the heating water temperature doesn’t increase the wood temperature, it adds energy to increase vapor pressure to increase vaporization. The water boiling point is set by ambient pressure. That means we can have heating water at 120’ degrees yet the wood is only at 89’F (at 35 torr). Someone may be thinking, “get to the point….” Well, this is the point: We are drying wood at cooler temperatures to obtain minimal degrade and for the best color. The end-user now has high-quality materials to work with. As a result, there is less chance that a customer complains that the wood in his hard work “moved”.