Proper Care and Feeding of Increment Borers

‘The tip is the most valuable part – protect it at all costs, even if it means cutting your finger with the blade. Your finger will heal, the tip will cost $200 to replace. (New modified rule set for Sky School goes like, “No bleeding – unless in the defense of the increment borer tip.”)’

Materials and prep

We have:

• Two 5.1mm borers (14”?)
• Sharpening block
• Rectangular file
• Conical file
• 0000 steel wool
• WD-40
• Beeswax

We should maybe purchase:

• D-shaped fish hook sharpener from Sportsman’s Warehouse or other fishing stores will be more durable than these fancy files we have.
• Rubber keeper or hair tie to keep the latch in place
• Flagging for tying to borers so we don’t lose them (we can maybe steal from labs if we don’t have)
• Padded box for conical file (will shatter if we drop it)
• Drying oven (though maybe we can use ovens on site)
• Durable paper towels or rags for cleaning

We should DEFINITELY purchase:

• Paper straws

Using the increment borer

• Decide which tree to core: if you want a signal of climate, choose a tree out on a crag away from other trees. Look for previous holes. Our limit, like the LTRR, will be 3 cores per tree and no more. Oaks are very hard and have stinky sap. Aspen trees with large cankers are likely full of gooey rot in the center, which will shoot out the end of the borer and drain the tree of its swampy ecosystem of microbes. No need to worry unduly about latex in this region, at least up on the mountain.
• Decide where to core the tree: lower down (right above root ball) gives you the best estimate of age, but you have to deal with buttressing and thicker bark. When coring at base, watch out for rocks the tree sucked up into its root ball! Stop at the first sign of resistance to protect the tip! Standardized “breast height” (high school kids love this term) at 1.3m gives you a better signal of recent climate.
• Follow the branches to estimate exact center of tree (the pith) that you’re aiming for. If the first one is slightly off, you can take a second core, using the original hole angle as a guide by placing the original core or a chopstick in the hole – but NEVER the spoon!!
• Assemble the borer: Unscrew and remove the spoon. Hook it into the bark of the tree or hand it to a responsible group member rather than placing it on the ground. CAREFULLY remove the borer from its handle. Lift the latch on the back side of the handle and insert the square end of the borer. Replace the latch (and the security band when we get one). Handle the corer very carefully, holding it at that intersection to avoid the latch suddenly failing.
• Insert the borer to the tree: Press against tree and begin turning handle right. Stop at the first sign of resistance!
• Remove the core: Once it is in as far as it will go (or you are to or past the center of the tree), slide the spoon in. At the end, it will pinch off the wood and break it when you rotate the apparatus. Back the corer out one full turn of the handle (360 degrees). Slide the spoon out. Admire the core, or store it in a paper straw and LABEL IT! Light wood is early wood, from March-May, due to snowpack. May-August is monsoon signal, sometimes with a false ring between early and late midway up the mountain.
• Remove the borer from the tree immediately. Do not get distracted by the core, especially if it is a Douglas Fir, which will swell around the borer and prevent its removal.
• Remember you can core up to 3 times if you missed the pith and actually need it. But no more than 3.

Cleaning and sharpening

• Clean the borer with WD-40 and a rag at the end of the day – every day it is used. You may need to clean it between trees if you get a really sappy one or are worried about spreading diseases (also use alcohol in that case?). Borer itself will rust without cleaning, especially on a rainy day. Have students hold it up to look at all the goop inside it.
• Teflon will wear off in 10-15 uses, but the steel is fine. Just don’t let it rust.
• 0000 steel wool is good to carry, not just because it’s less abrasive, it’s also a good emergency fire starter.
• Spray outside with WD-40 and wipe with a rag.
• Then spray WD40 into borer, wrap 0000 steel wool around tip of the spoon as though it’s a Q-tip, and push it down, spin it. Spoon is about the length of the borer, so it can help get things unstuck. This is much like cleaning a flute or clarinet, if any students are in band.
• If it’s REALLY plugged with wood, you need to take the borer back and drill it out with a small drill bit or a Swiss Army knife awl, but careful! Have a single dedicated person willing to take the risk of destroying the tip bore it down WITHOUT TOUCHING the tip!
• Sharpening the borers should happen if we notice long grooves in our cores or otherwise reduced quality of cores. To take a burr off, add a couple drops honing oil to the sharpening block, hold the borer at a 30 degree angle with sharpening block, make 2-3 strokes, then rotate and repeat. Doing that to the outside curls the metal in, creating burrs on the inside. So next you sharpen the inside: put the conical file inside the borer, but not so it touches all the way around, just on one edge. Rotate the borer to get contact between the file and the metal edge.

Processing the cores

• We need to dry them flat in paper tubes. A hot oven will curl them, but a drying oven (or low temp oven, especially with a fan) might work okay for ~18 hours. Curled cores can be uncurled by holding them above the steam of a boiling pot to relax them, then redrying them.
• Mount and sand them: Glue them to a flat surface or core holder (Elmer’s is great). Sand using a belt sander (400) to polish enough to see individual cells, but sanding block will work ok for us to just count rings.

References: Paul Sheppherd’s interactive online cross dating activities! [[1]]