Editor’s note: This column was produced before Gene Wengert died in 2025. It is printed here in memoriam.

Q. We take squares and turn them into round pieces. These pieces must follow the grain To achieve the highest strength, and must be perfectly straight after turning — and stay straight in use. We do get a few rejects. Any ideas?

A. You ask several questions. Here are some thoughts. Note that straight rounds are required, for example, for drum sticks to croquet handles, to baseball bats and pool cues. 

Straight grain. There is no question that straight grain provides a stronger piece of wood when the round item impacts another object. I remember 75 years ago when I was “playing” baseball that we were always told to keep the bat trademark facing upward,to avoid breaking the bat. The trademark was in the flattest grain part, so we were hitting edge grain. Of course, eight-year-old kids did not break bats, maybe hockey sticks.

When you see a bat or similar product break, the break does not go across the bat, but along the length. This, called,splitting or cleavage strength, is the weakest strength. 

Analogy: Have you been driving along the coastal shore, especially in South Carolina, Georgia, and Florida, and seen the baskets made of thin strips of wood? How do they get these thin pieces? 

Answer:  They pound the wood with a wooden mallet until the rings separate. So, it is not unusual to see a striking tool separate along the rings and not across the grain.

The big challenge is to detect the weakest links between the annual rings and also, during manufacturing, avoid initiating a splitting failure from the pressure of the tools that are rounding the square billet. A slowly turned billet will indeed be an advantage. 
But, how to find weak cleave strength before or after manufacturing is still a challenge. 

Juvenile core wood. The wood formed the first (approximately) 20 growth rings in a log — whether a bottom, middle, or top log from the tree — has wood that is different than the wood formed later. This early formed wood, called juvenile core wood, once formed, shrinks lengthwise with moisture loss and overall is weaker than wood formed later. 

There are also more growth stresses in the tree in this juvenile region. This difference is more or less permanent. The change from juvenile wood is gradual over the 20 years. 

Overall, this juvenile wood is weaker than mature wood. Juvenile wood and perhaps wood just a little more than 20 years, should be avoided in tools and impact handles. From a practical point of view, looking at the end grain helps estimated if the wood billet is from juvenile wood.

Warpage from machine. When the knives on a lathe or similar machine turn the billet in a round, forces are created that can bend then work in progress. 

Further, heat can be generated by the knives, permanently weakening the wood. Slow cutting with sharp tools is essential. On a lathe, a backup roller is essential to avoid bending the work piece while cutting.

Warpage from growth stress. There is stress in the living tree, which will be in the billet and cause immediate problems in the billet and workpiece. Basically, a warped billet will not produce flat final products and workpieces. 

There is no cure for growth stresses, although a complicated and lengthy process in acoustic instruments does come close.  The heat used likely reduces the overall strength. 

Warp from moisture change. To,avoid,moisture-caused stress, the billet must be very uniform in final moisture. The final moisture should be 8.5% MC with a standard deviation under 0.3. During several weeks of non-use, the products should be stored at 40% to 45% RH. Moisture change after sale is hard to control. From a practical viewpoint, any warp that occurs more than a day after manufacturing is moisture related.

Q. We have some inland Western red cedar. After putting on an oil-based stain, after about a week, we notice greenish, grayish streaking stains that are objectionable. Any ideas?

A. It is more common to have this color change due to bacteria in the living tree. Did you notice a funny odor from the pieces prior to finishing? Did you notice any shake (ring separation, wind shake)? Small zones of ring separation can be seen with careful examination of some photos. This is a 100% indication of bacteria in the tree.

The overall bacteria problem is called wet-wood, or bacterial wet-wood. Small pockets of extremely high MC are in the freshly sawn lumber. In fact, some logs have such a high MC initially that they do not float in water. They are called sinkers. Adding to the moisture issue is that much of the lumber is quartersawn, which requires 15% longer drying time. When this wet wood is finally finished, it traps some water and the blue, green or gray fungi can grow in the wet areas. It stops when the MC is lowered.

There is no cure for the bacterial activity. Instead, we need to make sure that the water pockets are dried under 20% MC. In undried wood, the wet pockets are mostly random, but the pockets do come mainly from lumber from the butt log. The pockets also appear as slightly translucent areas in undried wood.

It’s possible for the kiln operator to notice pockets when stacking freshly sawn wood. The operator would monitor the wet pockets to ensure they were under 18% MC before drying stops.

To scan a lot of prices of lumber at the end of drying, use a pin-less moisture meter. If a wet pocket is found (high moisture over 20%, while an inch away, we find 12% MC), you can use a pin meter to get the core MC. The cure for wet pockets is longer drying.

The wet pockets, if not eliminated in drying, will eventually dry in the finished product and shrink. The delayed shrinkage can be a major appearance issue.