by George Buehler

With our trees put to bed for the winter, January is a good time to do some of the menial things that haven't been taken care of during the growing season. One of the things that should be done is maintaining our tools. Tools can be relatively expensive and should be kept in top condition. If a tool is not sharp, rather than cut the branch cleanly, it can crush the limb cells, potentially leading to damage to the limb or diseases.

We will divide this article into two parts – care and sharpening.

CARE

One of the keys to keeping your tools in top notch working order is the normal care you give them both in use and in storage. It’s quite easy to finish a tool task and throw it back into your tool box. If you give your tools a little TLC after a session of use, they can last a lifetime. Probably the most important factor in tool upkeep is cleaning. As you cut branches or roots, the tool edge is coated with the sap/resin from the tree. If this is allowed to remain on the tool, it hardens over time or picks up dust and grime, making a sticky mess. In addition, the sap can get into the hinge, making the tool hard to open or close. Actually, if the sap does get into the hinge and is allowed to ‘set up’, the hinge can be frozen so that the tool doesn’t work properly.

When the tool was used during the growing season, it should have been cleaned at the end of the day. There are several ways to keep a tool clean. After the tool use was completed for the day, the tool could be dipped into a solution of Lysol/water (approximately a 50/50 mix), swirled around, opened and closed while the cutting edge and the pivot joint is under the solution, and then carefully wiped with a cloth or paper towel. Special attention should be given to the cutting edge of the tool. Also make sure to remove all the liquid from the hinge or it may rust shut.

Some hobbyists use turpentine or mineral spirits (both hydrocarbons) at the end of the day to remove the sap. Unless you are working on a very resinous tree, like a pine, this is probably unnecessary. Even working on a resinous tree, if you use the liquid cleaner routinely during the trimming process, most, if not all of the sap can be removed from the tool. If you do use a hydrocarbon cleaner, the tool should be cleaned with a good cleaning solution after the hydrocarbon is used.

After the tool is clean, it should be thoroughly dried to remove all traces of water; and it should be wiped with an oily rag to deposit a light coating of oil over the entire tool. Once again, the cutting part of the tool should receive special attention to ensure that there is a light film of oil on it. Sewing machine oil, which is a general purpose oil, should be used. Heavier grades oil, such as motor oil, is not generally used, since it is harder to uniformly distribute, and it leaves a thicker layer of oil on the tool. I know several hobbyists who use WD40 or similar penetrating oil to spray on their tools. Since I have not tried this, I only offer it as an option.

Normally, a lot of bonsai tools are used throughout the growing season. There are some, such at the root cutter, that are used in the spring and not used until the next transplanting session. There are some that are used once a month or so, others every week. I handle the storage of these tools differently.

For those tools used only in the spring, after it is cleaned, dried, oiled and wiped down, I add an additional drop of machine oil to the pivot. I then wrap the tool in a thin cotton cloth and store it on a shelf with my bonsai pots. Over the years, the cotton cloth has become covered with oil, which also protects the tool from rust during its storage.

For a tool used monthly, they are cleaned and oiled, then either wrapped with a paper towel or simply stored in a tool pouch. The tools used routinely are cleaned and usually oiled after use. Because these tools are used so often, I don’t always oil them after every use – but they are cleaned after each use. I do try to make it a point to oil the pivot at least weekly. The tools that I use routinely – concave and wire cutter, trimming shears and knob cutter, are stored in a tool roll. These tool rolls come in a number of designs and are made of polyethylene, leather, or cotton. One of mine is a polyethylene material with individual compartments to slip the tools in. The less used tools, are stored in a different tool roll. If I will be attending a workshop, I pack the tools I think I need in the polyethylene tool roll for easy transporting.

Some thought should be given to how the tools are transported to workshops. There are a number of options to consider. Some hobbyists use a normal fixed sided tool box, others use a soft tool bag, and some use a 5-gallon bucket equipped with a holding mechanism on the outside, while others simply use the tool roll. There are advantages and disadvantages to each. The fixed sided tool box is, of course, not expandable; therefore, it is important to find the right size. Dimensions of about 12” by 5” by 6” will hold a lot of tools. The 5 gallon bucket, although I haven’t used it, seems to be rather awkward. Transporting the tools in the storage tool roll works well as long as the tool roll has a ‘flap’ to keep the tools from sliding out. The soft sided tool bag is what I use since it is “slightly” expandable, it is light weight, and holds a lot of tools. Mine was purchased at a big box store and cost about $15. It has side pouches both on the inside and outside, making it convenient to hold last minute supplies, keys, etc. Probably the most important thing in tool storage or transportation is to ensure that the tools don’t hit each other, especially the blades or tips of the blades. If the blades hit, they can knick or even break. Depending on the tool quality or supplier, some are supplied with a plastic cover which goes over the blades. If this is the case, always put the cover back on the tool to help prevent damage.

Bonsai tools are often used out-of-doors and subjected to large amounts of moisture, and often perspiration. Under these conditions, they are prone to rusting. The stainless tools will not rust unless they are exposed to a moist acid environment, which is a definite positive for their purchase. The tools that are plated also have a good corrosion resistance.

There will be times, no matter how careful you are, when a tool will start to rust. Because bonsai tools are used often, rusting normally is slight. When there is rust, the tool often can be cleaned of the rust by simply rubbing with a tooth brush or other stiff bristled brush dipped in a dish detergent, dried thoroughly, and then wiped down with an oily rag.

If the tool has major rusting from being left outdoors or by other abuse, 4 aught steel wool or a fine synthetic steel wool may be used to rub off the rust. A gentle pressure should be used to prevent scarring the metal of the tool. Although I have not had this problem with my bonsai tools, I have had an occasion when another tool was left outside by mistake. When I found the tool, it had a good layer of rust on it. I used synthetic steel wool moistened with machine oil to clean it off, thoroughly washed it with mild soap, dried it and then oiled it down and thought nothing more about it. I did find that this tool had to be routinely treated because it had a propensity to again rust even stored in my ‘real’ tool box. The key here is to make sure the tool is dried and oiled before storage.

SHARPENING

If bonsai tools are used properly, the cutting surfaces will last for years without the need for sharpening (grinding an edge). Concave cutters and knob cutters have a fairly complex blade geometry which makes proper sharpening beyond the scope of this article. You can 'touch up' the edge of your tools if you do it on a routine basis. If you wait for the tool to get dull or if it gets a nick in it, this method will not work. If the tool is dulled by abuse such as cutting wire with a concave cutter, it may be better to simply purchase a new tool. Professional sharpening, if you can find a sharpening shop to do it, will be expensive. They may charge more to sharpen the tool than the cost of a new one. If you purchased stainless tools, then by all means look for a local sharpening shop that will work on them. For straight edge blades, like a shear, professional sharpening shops will generally sharpen the tool while you wait.

Another problem with bonsai tools is that they generally are riveted together, making sharpening more difficult. In addition to the complex geometry of some of the tools, the straight blade tools, like shears, are short bladed, making getting a sharpening stone over the entire cutting length almost impossible.

My technique for touching up the edge of my tools starts with a set of diamond pocket stones. They are similar to a fingernail file but are made of plastic, and one side is coated with diamond grit. They come in coarse, medium, fine, and extra fine grades. They are manufactured to sharpen the edge of woodworking tools, and as such, they can remove a lot of metal quickly – especially the coarse one. If the tools are touched up routinely, the fine and extra fine stones are sufficient.

Since the straight blades are the easiest to touch up, you should start with one of these first. Open the shear to its fullest extent – remembering that even though the tool may be dull for cutting a branch, it probably is still sharp enough to cut skin – then using a black magic marker, color the cutting edges of the tool this is the beveled portion of the blade. Using the fine stone, hold the stone firmly to the blade making sure that the stone is flat on the cutting edge angle. Make one or two passes from the pivot end to the tip of the blade, holding the pocket stone firmly (but not with a great amount of pressure) against the blade. Look closely at the edge of the blade. If the stone is held at the correct angle, most, if not all of the magic marker ink should be removed. If only part of the coloration is removed, the stone is not being held at the correct angle and more attention should be given to holding it flat against the blade. Make sure each blade receives the same number of 'strokes'.

Some people believe that they should touch up the back side of their shears – the flat portion of the blade. This is not generally recommended. If too much of the back side is taken off, the contact between the two halves will be reduced and the cutting ability will also be reduced. For concave cutters, the procedure is much more complicated and care has to be exercised. Describing the method to use is harder than the actual sharpening. Remember that the tool is only being touched up, not really sharpened.

First look at how the blades close. They should just meet, with the amount of closing being controlled by the “stop pin”. This pin, which is in one handle, controls where the tool closes. When the one handle just meets the stop pin, the blades should “just barely” touch. If the blades touch each other before the one handle meets the stop pin, the pin will have to be nudged over so that the moveable handle meets the pin before the blades touch. With a "small" hammer, gently tap the pin toward the opposite side. Tap the pin only once and check the closing. If the blades touch before the handle hits the pin, repeat the tapping until the handle hits the pin just as the blade touches. If the handle hits the pin before the blades close, either the pin has to be tapped the opposite way or the pin needs to be touched up. If the pin needs to be ‘thinned’, it is done by using the course diamond stone and grinding a little off the surface that stops the blade closing. I have only had to do this adjustment once, and that was because the tool was dropped which apparently bent the pin slightly.

Now for the sharpening. Hold the concave cutter with the blade CLOSED. Look at the tool carefully and notice that one of the blade halves just slightly (about one millimeter) overlaps the other. Carefully run an index finger over the mating surfaces and the slight overlap can be felt. The blade that crosses over is called the upper blade, and the one underneath is called the under blade. Remember, this crossing over is very slight.

Once again, mark both of the edges with a magic marker. The technique used is to ensure the diamond stone follows the outside contour of the blades. Open the cutter to its widest opening, with the under blade away from you and the cutting edge facing you. Hold the fine diamond stone so that it will follow the blade opening. Check that the stone meets the blade uniformly, and then stroke the blade with the stone from one side of the blade to the other. Look at the magic marker ink left on the blade. Most if not all of the ink should be removed. Make four or five strokes across the blade.

Now close the cutter and hold the tool so that the upper blade is toward you with the cutting edge away from you. Keep the tool closed. Hold the diamond stone on the upper blade and push it away from you, going from one side of the cutter to the other, making four or five strokes. After I wrote the above, I followed the instructions and noticed that one of my concave cutters had a second bevel on it – a very thin angle where the blades met. This required running the diamond stone over this angle a couple of times.

If you ‘touch up’ your tools routinely, they will make a very clean cut. Shears and concave cutters may need to be touched up once a month, or even once a week depending on the amount of use. Unless you are extremely skilled at sharpening, you should not try to use an electric sharpening machine on your bonsai tools. They can be quickly ruined by taking too much off a blade. However, the manual diamond stones can lengthen the life of those favorite pair of shears you use and produce a very clean cut.