Even top-of-the-line tools need to be cleaned and sharpened regularly to perform their best. Sharp pruning tools make cleaner cuts, allowing plants to heal faster, and sharp digging tools save you valuable time and energy when working in the garden, not to mention a backache or two. Midwinter, when the growing season has slowed and outdoor activities move inside, is the perfect time to devote to prepping your tools for the spring season ahead.
The first step with end-of-the-season tool maintenance is a good cleaning. Throughout the gardening season, it's important to clean sap and dirt off your tools to prevent the spread of soil-borne diseases and weeds, but your annual cleaning should be even more thorough. Sap and dirt left on tools during winter storage will attract and hold moisture, encouraging the spread of rust.
Start by disassembling any tools that have moving parts, such as pruners, shears, and loppers. Remove the accumulated rust and dirt from all metal surfaces with a wire brush. If necessary, gently sand away stubborn rust on pruners and loppers with fine steel wool; use medium-grit sandpaper on larger tools. For a very heavy coat of rust on shovels, spades, or hoes, use an electric drill with a wire brush attachment. Whether using a hand-held brush or one on a drill, always wear safety glasses to guard against errant rust particles. Remove stubborn sap with a solvent such as turpentine or Break Free CLP, a synthetic oil containing solvent.
Once your tools are thoroughly clean, you can tackle their blades' cutting edges. When sharpening, try to maintain the original factory bevel or angle. If the blade is beveled on only one side, as with bypass pruners, then sharpen only that side. File the flat side of the blade only to remove burrs (rough ridges of metal) caused by the sharpening process.
Use either a whetstone or a mill bastard file as a sharpening device, depending on the tool you're sharpening. Be sure you know which style of blades you are working with, and sharpen accordingly.
For pruners, you can use a whetstone (also called a honing stone), which produces a very sharp cutting edge. Start by applying a few drops of oil or water to the whetstone, depending on the type of stone you're using. The liquid carries away metal filings and lubricates the surfaces, making it possible to achieve that very sharp edge. With the beveled side of the blade against the stone, rub the sharp edge of the blade toward the stone in a curved motion, as if you were trying to shave off a thin slice from the stone. If the blade has any nicks, use an 8-inch-long fine-grit mill bastard file to remove them; a medium-grit file may be needed to remove large or numerous nicks.
To sharpen larger garden tools such as shears, loppers, shovels, spades, and hoes, use fine- and medium-grit single-cut mill bastard files instead of a whetstone. When working with a file, stabilize the blades you're sharpening in a vise or against a solid surface to avoid injury and ensure an even and correctly angled stroke of the file. Always push the file across the blade in a motion away from your body and moving diagonally. The direction of the diagonal depends on what type of file you're using; the objective is to have the cutting teeth on the file biting into the metal on the tool. Most mill files are made for right-handed people, and the serrations are angled so they will grip the steel only when pushed in a left-to-right, forward motion. Do not use oil when sharpening with a file; metal filings will accumulate and clog the file's serrations.
Bypass pruners or loppers work like scissors, except that the blades are slightly curved to hold a stem or branch in place. Sharpen only the beveled side of the cutting blade. Do not sharpen the flat side of the cutting blade, or any part of the opposing blade because you will create a space between the blades that will prevent their clean, scissorlike cutting action.
Anvil pruners and loppers have a cutting blade that comes down on an anvil, cutting a stem as if it were laid on a chopping block. The cutting edge is beveled on both sides, like some knife blades. Sharpen both sides of the cutting blade from the base of the blade to the tip. Take care not to remove too much metal; you want to retain the original shape of the blade so it will meet the anvil completely.
Hedge shears, like bypass pruners, also work like scissors; the cutting blade is beveled on the inside edge. Lock long and somewhat unwieldy blades like these into a vise to ensure a smooth, even stroke of the file. Sharpen the cutting blade with a medium-grit mill bastard file, running it from the bottom of the blade to the tip. Put a fine finish on the blade by switching to a fine mill file. File the outside of the cutting blade and the opposing blade lightly to remove any nicks or burrs.
Shovels, spades, and hoes hold up best with blunt cutting edges, since they are used for digging. Go at them with a medium-grit mill bastard file. It will not remove too much metal or put too fine an edge on them, but can work out the nicks and chips and make a straight bevel. Brace the tool against a solid surface (or fasten it into a vise if you have one) and push the file forward along the tool's cutting edge, in one diagonal direction--from left to right, or vice versa, depending on the type of file you're using--so the file is gripping the steel. For all three tools, smooth sharp edges and remove burrs with a fine-grit file or small whetstone.
Once your tools are clean and sharp, they're just about ready for storage. A few more steps at this stage can ensure that your tools will retain their sheen through the winter months.
Clean wood handles with a stiff-bristled brush, and smooth down nicks and splinters with medium-grit sandpaper. Coat wooden handles with boiled linseed oil to help preserve them and prevent splintering and breaking. Sand off the factory varnish and wipe on boiled linseed oil with a cloth; apply several light coats, letting the oil soak in after each application. Wipe off any excess with a dry cloth.
If the plastic handles on your tools are tearing or wearing thin, you can remove the coating with a craft knife and replace it with a liquid or spray plastic coating. It's sold at hardware stores under the name Plastidip. Dip or spray the handles and clamp a metal portion of the tool lightly into a vise and let dry.
Once the handles are in good shape, reassemble your tools. Oil the pivot bolts and adjust them so the blades are tight enough to provide a strong, clean cut. Lubricate all metal blades and the heads of shovels, hoes, and rakes with a light machine oil or a synthetic oil such as Break Free CLP.
Clean, sharp, and properly coated, your tools are now ready for storage. Store them in a dry place away from heat and moisture. Hanging tools is an effective way to keep moisture at bay. Small tools such as pruners will do fine either hung or stored in canvas gardening bags. When spring comes around, you will have a host of tools ready to serve you.
* Clean all dirt, sap, and rust off your tools before sharpening them.
* Stabilize tools for sharpening by bracing them against a solid surface or clamping them in a vise.
* Sharpen only the beveled side of a blade.
* File the flat side of a blade only to remove burrs.
* Always file in strokes away from your body.
* Don't drag a mill bastard file backward over a
blade on the return stroke.
An electric bench grinder is the most efficient way to recover the cutting edges on shovels, spades, hoes, and lawn mower blades. A grinder has a tool-rest platform that enables you to position the tool to achieve a more exacting edge. However, grinders create intense heat, which can compromise the temper of steel, making it brittle. You can also take off too much steel--and fast--with a rapidly spinning grinder wheel. If you do use one, periodically immerse the tool you're sharpening in cold water to cool it down, and take off small amounts of metal at a time. A small grinding wheel attached to an electric hand drill can do the same job as a bench grinder. With either tool, always wear gloves and safety glasses.
1. The first step to reconditioning your pruners is disassembly. Remove the pivot bolt with a wrench and take out the spring--with a screwdriver, if necessary.
2. Clean all sap and dirt out of your pruners with a wire brush and a rag, and then buff
the blades with fine steel wool.
3. Unlike oil or water whetstones, a diamond whetstone does not need to be lubricated. Sharpen pruner blades by swiping them over the whetstone in a curved motion, trying to maintain their original bevel.
4. Coat clean, sharp blades with light machine oil to proetect them against rust.
Image courtesy of NGA member "springcolor".
Article published on June 23, 2008.