Most streaming studies rely on increment core samples, and especially for wood anatomical analysis, we rely on very high-quality increment cores. Increment cores taken by a cordless drill are subjected to lower mechanical load and are therefore less damaged. Begin by assembling the increment corer and selecting the coring position on the stem of a tree, depending on the research question.
After selecting the coring position, place the corer at a right angle relative to the direction of growth of the stem and place a pusher at the rear end of the corer to stabilize it while drilling. Achieve a stable position and lean against the pusher to apply pressure to the cutting edge. Turn the corer handle with both hands until the threaded part of the drill fully turns into the stem.
Once done, release the pressure and remove the pusher. Next, start turning the corer handle with both hands until the corer has reached or drilled through the pith. Check this by holding the extractor on the handle aside from the stem.
Take the extractor with the open side on top and insert it fully into the corer. Turn the corer backward with one full turn to break the core from the stem, and pull the extractor out of the corer. Remove the core from the extractor and store it in a paper straw before removing the corer from the stem and storing it in the handle.
To the cordless drill equipped with a torque booster, add the special adapter for the increment corer developed at WSL. Once the coring position is decided, place the corer at a right angle relative to the direction of growth of the stem. Achieve a stable position, hold the cordless drill tight, and apply pressure on the cutting edge.
Start the cordless drill, turning slowly until the threaded part of the drill is fully cored into the stem. Then, increase the speed until the corer reaches or drills through the pith. Once done, remove the cordless drill from the corer, place the handle on it, and use the extractor to remove the core as explained.
Store the increment core in a paper straw. Remove the handle and place the cordless drill on the corer before removing the corer from the stem. To use the WSL sharpening support, take the newly designed holder and place it on the ground.
Place the cordless drill, including the increment corer, at the designated support points, and close the mounting bracket to fix the cordless drill. Start the cordless drill by fixing the Teflon block on the starter button and let it run. Take the conical grinding stone and grind the inner side of the cutting edge with it.
Next, take the rectangular grindstone and grind the outer side of the cutting edge to de-burr it. Remove the Teflon block from the starter button to stop the drill. Open the mounting bracket to release the cordless drill, and take the device out of the holder.
To check the sharpness of the cutting edge, remove the increment corer from the adapter of the cordless drill. Place a sheet of paper on the wooden board of the sharpening support, and place the cutting edge of the corer on the paper while holding the corer vertically. Turn the corer while holding it vertically without applying pressure to the corer.
Lift the corer to check for a round piece of paper inside the cutting edge. If the round piece is present, the corer is sharp. If not, repeat the sharpening procedure.
If the outside of a core is not smooth, repeat the entire procedure. Place a long glass slide next to the microtome. Add some water in the middle of the slide along its entire length.
Then, place the core in the sample holder of a core microtome. Lift the sample holder until the core almost touches the blade's edge, and pull the blade over the core to cut off the top. Place the knife at the beginning of the core again.
Lift the sample about 10 micrometers and repeat the cutting procedure to obtain a plain surface of at least two-millimeter width. Next, brush a cornstarch solution on the cut surface, and remove the surplus solution from the top of the core using a piece of cloth. Place one side of a water-soluble tape to the start of the core with an overlap of one centimeter and the beginning of the core facing the microtome blade.
Attach the tape to the surface of the core by stroking the tape on the surface using a finger. Then, lift the sample in the microtome 15 to 20 micrometers using an overlapping piece of the tape, and place the microtome blade at the edge of the core. Once done, cut the section while holding the end of the tape.
Take a thin section stuck on the tape and place it on the line of water on the glass slide prepared earlier with the cut facing down. After approximately 10 seconds, start removing the tape from the section using tweezers while taking care that the section remains on the glass slide. During coring using the cordless drill, none of the cores were deformed due to the pressure exerted on the cutting edge during the first phase of drilling.
The cores with no smooth surface and scratches and cracks indicated the need to sharpen the cutting edge. The protocol saved time in the lab and improved the quality of the micro sections. Even if using a cordless drill, you want sharpen the corer regularly to ensure the sampling of high-quality cores.
Reducing the mechanical stress while coring reduces the risk of causing micro cracks in the cores. For this, lab work for preparing micro sections is reduced to a minimum. The ability to prepare micro sections of entire increment cores allows a simplified time series analysis for wood anatomical analysis.
