Timborana

Timborana

I had purchased a relatively small block of wood labelled Timborana at some point in the past, from where and exactly when are now mysteries. I had never worked with this wood before so it presented new opportunities and, it would prove, new challenges. While I am pleased with the end result, the process of getting to that point was not always easy.2014-09-21 00.54.29

Initial Impressions and Reaction

When I cut the wood to round I noticed immediately that it was very dry and that it splintered very easily. I regret now that I didn’t take interim photos to demonstrate this. As is now my new habit, I marked center on both sides of the blank, while also marking which side would be the “face” of the bowl, the side on which the face plate would be mounted, and thus consequently largely cut away. Once between centers I turned to round. Once the lathe stopped, I could immediately see some of the worst end grain tearout I have ever seen along with gross splintering of the wood along the grain lines. And the pores were enormous, easily visible to the naked eye. But most grievous to me was the odor, or more accurately, the effect of any sort of dust from the wood. Immediately, my nose and throat were on fire and I had the uncontrollable urge to cough! I have worked with dozens of different species of wood at this point in my time as a wood turner and never have I encountered an adverse reaction to any wood, until now.

Certainly I have heard of such reactions and I have even seen them first hand with my Dad who has suffered fairly severe skin irritation in the form of actual fluid-filled blisters from working with an unidentified wood local to where he lives that was being removed to make way for a solar energy installation. Once the reaction occurred, I went upstairs to check the excellent reference source, the Wood Database, which contains rather comprehensive information on hundreds of different wood species, including known allergic reactions and health risks. Timborana wasn’t listed as having any known reactions but it does belong to a genus that has other species that are known to cause allergic reactions. I don’t think I would classify my reaction as “allergic” per se, but it was certainly not a benign reaction. The only way I could continue to work with the wood was through the use of a N95 respirator. Every time I tried to dispense with it, the reaction occurred again.

Is It Timborana?

I had noted that Timborana, at least the piece I had purchased and labeled as such, was quite soft and easily marked using a hand awl and nothing more than hand pressure. I was quite surprised to read in the Wood Database that Timborana has a Janka hardness of slightly greater than hard maple, which I know from experience is barely marked, if at all, by an awl using nothing more than hand pressure. This made me question whether the wood I had purchased was misidentified, which happens more than many wood workers might know, especially with imported exotic woods. The main use of Timborana was noted as being flooring planks, but the wood I was working with would be immediately ruined by most any hard shoe, much less something accidentally dropping on it, so this seemed suspicious, especially when coupled with my reaction to the wood which had never before been reported with Timborana. If I were especially prone to such reactions, I might chalk it up to my sensitivity, but since I have never had a reaction before, even to the wood that so affects my Dad, this seemed unlikely. However, the other listed characteristics of Timborana, especially its high silica content and consequent blunting effect on cutting tools, as well as general appearance and tear out risk, all seemed to fit. I could clearly see that a small amount of sapwood remained attached to my piece and it was noted in the Wood Database that the sapwood was sometimes not clearly demarcated from the heartwood. My only reasonable conclusion was that I was working with the sapwood of the Timborana tree, which might have some similar appearance to the heartwood, but which has the characteristic softness frequently associated with sapwood. Either that is the explanation, or the wood I had was completely misidentified as Timborana. I remain uncertain as to which is the actual explanation, but I will proceed with the assumption that it was Timborana, but sapwood, not heartwood.

Definitions Needed Please

By the way, I have discovered recently that “hardwood” does not necessarily refer to the measured hardness of a wood; it only refers to the wood coming from a broadleaf tree which reproduces via flowering. “Softwood” refers to coniferous and evergreen trees and their wood. Some woods labeled, therefore, “softwood” may in fact be harder than woods labeled, accurately, “hardwood” For example, balsa, one of the softest and lightest woods known, is technically a “hardwood” because of the type of tree from which it is harvested.

Process of Turning

Because the wood was relatively soft and friable, tear out was a given and even with frequently changed carbide bits in my Easy Wood Tools, which were quickly dulled by the noted silica content, I was not able to achieve anywhere near the cut finish I can usually achieve with a harder wood. This necessitated sanding, of course, and more than usual, but because the wood was soft it sanded smooth quite quickly and easily. The pores remained quite visible but there was no discernible rough feel because of them. I actually liked the pores because they lend a unique appearance to the finished piece. Some wood turners will intentionally fill pores to achieve a smoother glossy finish, but I always prefer to let the wood’s actual character come through.

Finishing With Tung Oil

However, because of the high porosity of the wood, I wanted to use an oil finish that would really soak into the very dry wood and help protect it because of it softness, and therefore I experimented for the first time with Tung Oil. Tung Oil is a very old fashioned finish, derived from the nuts of the Tung tree, that isn’t much used by many woodworkers these days because of its extended drying time. It can take weeks to fully cure and many people just don’t have that type of time to invest or they are more accustomed to the rapid drying finishes available today. In addition, Tung Oil soaked rags must be stored in sealed containers, under water, or burnt, because the reaction of the Tung Oil with oxygen as it cures and hardens, is exothermic, heat producing, and that heat can be sufficient to ignite paper or cotton. I routinely store all rags and paper towels with any finish contamination in a sealed and water filled five gallon bucket, exactly for this reason. Also, once opened, the remaining contents of the container must be protected against oxygen contamination since this will cure the remaining oil, rendering it useless for future applications. The Tung Oil should be as fresh as possible for the best results. Despite its potential risks and hassles, which are mimicked by other finishes anyway, Tung Oil is excellent on very porous woods, it is food safe, and it also fills pores effectively without being plastic to the touch. I used a product clearly labelled pure Tung Oil, and this distinction is important since some finishes are labeled with weasel words such as “Tung Oil Finish” which might, in fact, contain either very little actual Tung Oil, or in many cases, none at all. Only products clearly labelled as “pure” are assured to be Tung Oil. Some Tung Oils are polymerized, which means they have been heated prior to bottling to make them set, cure and dry faster, but the product is still Tung Oil. My product was not polymerized to my knowledge. Following the directions, I diluted the oil 1:1 with paint thinner and applied a total of four coats, waiting the indicated 30 minutes in between each coat. The thinner makes the oil flow on more easily as the pure oil is the consistency of maple syrup and it could be challenging to make an even application. The wood really absorbed the oil, especially on the end grain, which darkened rather noticeably compared to the other areas, although Tung Oil is used when initial darkening and darkening over time is NOT desired. While the piece is still oily to the touch, I expected that, and am allowing it to continue to dry over time, which I have plenty of since it doesn’t need to be touchable until Christmas time when it will most likely be given as a gift.

Final Thoughts

Overall, I rate the experience with Timborana as a success even if it did present some new challenges. The Timborana also presented me with the opportunity to try a new finish as well as experience with how immediate and incapacitating a reaction to wood, or its dust, can be. I will be hesitant to use Timborana in the future because of the reaction, but I would certainly encourage others who have access to Timborana to give it a turn and see how they experience it, especially if they obtain a piece that has different characteristics to the one I had, which might either be more definitively Timborana, or contain more heartwood. Either way, I welcome feedback from other users of this unique, if somewhat challenging, wood.