I’ve started quite a few new projects for the year, hopefully setting them on a path to become excellent bonsai in the future.
Perhaps when I take them further in development I’ll give them their own designated posts but for now check em out.
Ficus Microcapra “Tiger Bark” (2014–)
This tree was actually among one of the original bonsai I started with. It began as small cutting grown material from House of Bonsai in late 2014. I proceeded to repot it and let it grow freely for the year. Unfortunately the nebari on this tree was typical of the ikea two leg bulbous roots so in late 2015 I opted to ground layer the tree and completely rebuild a new root system. This spring I’ll do further nebari work as well as give the first major cutback and preliminary styling.
The tree now:
Hackberry (celtis occidentalis)
The next project is a hackberry I purchased from Bob at Kimura Nursery. It was excellent material with lots of low branches to choose from, a decent nebari, and nice graceful taper. I cut back the main leader and will allow a low branch to run to give additional girth near the base.
On this tree I chose to screw the base to a wooden board. Doing so forces the tree to grow roots laterally and prevents downward growth. This enables the surface roots to thicken more building a better nebari or root spread.
The tree was potted in a wooden grow box I made. No photos of it but nothing special. Onto the next project.
I was fortunate to find a nice sized monterey cypress as regular nursery material. It had a decent sized trunk as well as good nebari or root flare. I went ahead and purchased it and set out to do a full styling from raw material. It was quite a challenging project for me but I’m very happy with the results. I reduced about 50% of the root mass and probably ended up removing about 70% of the foliage to achieve the final design. Unfortunately no pictures prior to repotting to a terra cotta trainer but here it is before styling.
In styling the tree it was important to me to create a convincing design but also to incorporate elements seen in the iconic monterey cypress peppering the California coast. The harsh coastal winds produce twisted contorted growth and flat foliage pads.
I chose to initiate the orientation of all branches upwards before flattening out at the tips to emulate their natural counterparts. Wiring all the branches in the same fashion also helps bring cohesion to the design
As “younger” nursery grown material it had multiple sub trunks. I opted to remove the thicker trunk that would be hard to introduce movement to while keeping leaving those that would lend towards clean graceful lines. Here is the finished tree:
As with any 3-D object, a tree no less, it is hard to portray depth in a photo. The back center trunk appears to be competing with the main left trunk and the foliage feels cluttered and messy. Unfortunately I do not have a good lighting set up so the highlights on the center trunk also give the illusion it’s on the same plane as the front left trunk.
While I can ascertain (that’s what they all say right) it looks better in person there are still several things you can take from a flat photo. It helps bring out lines and focal points you’d otherwise wouldn’t notice. Also excellent trees often look good in person (3-D) and in photo (2-D) due to a clear definition of lines and movement. Good or mediocre trees can look good in the 3-D aspect but fail in the 2-D lacking that same clarity.
To my defense as nursery material there is a lot of strong outward apical growth. To style the tree I end up removing most of that leaving the weaker interior foliage. I could remove another 20% of the foliage and do more fine wiring but it would stress a tree that already has had considerable work done to it. Admittedly my wiring still needs work but it improves with every project I do.
Typically I like to do a rough styling and then after the tree has recovered with lots of strong interior growth I do the fine foliage wiring. I’ll have to keep close watch on the aftercare on this tree to ensure I don’t lose any branches or trunks.
There’ll be more to come but that’s it for now. I also thought I’d take this chance to update you guys on my apprenticeship ventures.
I’m still probing Taiwan and have sent out letters but no bites yet. On the contrary I may have a possible opportunity to apprentice in Japan. No guarantee yet, but it’s something worth exploring to see if I can pursue. I may have to swap my studies in Mandarin to studies in Japanese if it works out.
I apologize for not getting out articles and translations on the Taiwanese bonsai book I showed 2 posts back but it’s been a bit more busy than I had hoped for. I’m still heading strong towards my goal though and I’ll keep you guys updated along the way. Thanks for taking a look and I’ll see you on the next post!
*note, I’ll be editing and improving this article over time so check back or ask me any questions on anything you didn’t get*
I’m a DIYer kind of person. I hate sending things out to get fixed or spending money that I could otherwise save. Concave cutters, the quintessential bonsai tool, seldom need sharpening due to the robust design and wide edge angles but like anything else, repeated use will wear it down.
My old pair of concave cutters from Lee Valley was standing on it last legs. Wobble in the pin, chips, rolled edge, and more. As my first and only concave cutter it was abused and used to cut things I probably should have cut. I decided to purchase a new pair from Kaneshin. And of course after a few days I somehow managed to chip the edge. I have a fairly high skill with waterstones and was confident I could repair it. In doing so I understood the criteria for concave cutters to cut well but also realized that there are no comprehensive guides online on how to do so.
I decided to make a guide through the restoration of my old pair.
This guide will be organized in 4 sections:
Burrs and Finishing
PART I: Criterion
The first component is seems simple but there is a little more too it. I will elaborate below.
The second criterion is necessary to ensure a clean cut. If the edges do not meet you have a branch with intact wood fibers in the middle.
Lets take a look at my old Lee Valley tool:
From both pictures its evident that the blade is chipped in the center and to lesser degree, on the top. There is another thing worth pointing out. Notice the white hair line immediately below the large chip. That’s light passing through the blades. The edges do indeed meet one another and they are offset (discussed below) BUT they are not touching as evidenced by the light coming through. I’d like to emphasize that the blades are FULLY closed. The light breaking through it not because of that.
For comparison here are my freshly sharpened Kaneshin cutters.
Here is a diagram better explaining this concept. (the text may be hard to read in mobile)
Now I’d like to say that some variance is not that big of a deal. Your concave cutter will still function properly. But we should avoid any significant deviations as gaps between the blades will prevent them from cutting cleanly.
Lastly the tips must be offset:
That black hairline on the top is the edge of the other blade offset over the other. If the tips meet flush even every time you cut a branch they’ll snap together. This can dent, chip, and dull the tool.
At the same time keep overlap as small as possible. You want just enough to prevent the cutting edge from damaging each other. Too large of an overlap and you’ll notice you have trouble cutting branches when the cutters get close to the center.
In short when we sharpen this tool we want to think about these 3 points and ensure we preserve them throughout the restoration process. There are some other important aspects worth consideration that will be discussed in the technique section.
PART II: Tool Selection
From my days working for a knife dealer and being a collector I amassed a decent amount of sharpening tools and water stones. Here is some of what I use:
You do not need expensive fancy tools to sharpen concave cutters. I’ll discuss some of the options and what my preferences are and why.
There are 3 main categories we can think about. Waterstones, diamond abrasives, and sandpaper. To start off I’d advise against using sandpaper. It’s the cheapest but also wears down fast. Arguably if you are only sharpening your tools once a year sandpaper can be a viable option. If you are insistent on using sandpaper there are some things to know.
Use the black silicon carbide sandpaper you find at auto stores. The brown aluminum oxide or red ruby sandpapers will not do a good job at removing metal.
Second, use a hard backing behind the sandpaper not a soft one. This might seem counter intuitive at first but hear me out. Because of the convex outer bevel it may seem logical to use a softer material with some “give”. Maybe a leather belt or piece of rubber. Do not do this. While that “give” allows the sandpaper to wrap around the curved outer face it also wraps around the edge. This can cause blunting or rounding of the tip. The sharper and crisper the edge the better it will cut.
This leaves us with waterstones and diamond abrasives. Waterstones are great tools but they have a drawback–dishing. As you wear the stone abrasive media becomes loose and dishing occurs. This is especially pronounced as you have such a small contact area for a concave cutter compared to say a kitchen knife. With a kitchen knife you abrade nearly the whole surface of the stone continuously so it stays relatively flat. With the concave cutter you are only abrading a small region at a time. The medium you sharpen on is reflected on your edge, so if the stone is dished your edge will not be straight! This creates variance on traverse axis or unequal width along the edge of the blade.
This brings me to my recommendation: diamond benchstones. Actual to be more generic any fixed abrasive media benchstone. In essence something that will not dish. Diamond abrasives are great since they cut well and would be my main recommendation especially if you are sharpening stainless tools. (The “stainless” quality in stainless steel comes from chromium, which also makes the steel more abrasion and wear resistant=harder to sharpen)
This is what I’m using. A double sided coarse/fine DMT dia-sharp 6 inch stone. I bought mine many years ago when it was a bit cheaper but they run about $50 now.
PART III: Technique
You can hold the concave cutters and position the stone however you want. The 2 things you always want to keep in mind is consistency and geometry.
On the first part. Consistency means repeatability. Every stroke you do on the stone needs to be the same abrading the intended region. By many years of practice I can do this by feel but there are other ways aid less experienced hands. One method is the sharpie trick. Simply color the bevel of the concave cutter with a sharpie and begin working. After a few strokes on the stone pick up the tool and look at the bevel. The areas where the sharpie is gone are the regions you abraded. Doing this can give you a sense of what you are doing and improve your precision. There are lots of videos and guides on this so you can look up the rest yourself.
Geometry is a big key component. Good blade geometry means it will cut well. Poor geometry means a lot of rough cuts and resistance through branches. Generally speaking you want as an acute of a edge angle as you can get without compromising the integrity of the tool. Too thin and you get chips or cracks. Too thick, it’ll be tough but it won’t cut for a damn. Any half reputable manufacturer of your concave cutters probably already know ideal geometry their blades should be ground at and is likely produced within a range of it.
This means you should try to maintain the current blade geometry of your concave cutter.
You match the angles the bevel faces are ground at
– Inner face is flat so this is easier
– Outer face is curved, harder
Abrade the outer and inner bevel faces the same amount
Use the sharpie trick
– Sometimes I rush through things only to finish and see I ruined an edge
– Using a sharpie and working slow will make sizable difference
– Although you may be holding the blade flat to the stone if you put a lot of pressure on the tip, more metal will be removed from the tip
– Lack of even pressure is what causes varience of the blade width along the edge or “high” and “low” spots
– Try to consciously think about holding it steady and applying force across the length of the edge
Now finally to the sharpening itself:
I’ve said before it doesn’t matter how you hold the cutters. You just want to ensure you can keep it steady and brace it against the benchstone. Here’s how I do it:
Step 1: Working the outer curve
**As mentioned before you want to keep the overlap at the tip. It’s better to start with the undercutting blade first instead of the over cutting one. In the former at most you risk increasing the size of the overlap which can be remedied by working down the over cutting blade. In the latter you could actually could remove the overlap. You could restore it by working down the opposite blade more but is the more difficult approach**
I like to start on the outside and pull back
As you pull back you want roll the bevel forward. Think sweeping motion.
Continue to pull back until you reach the tip
Once you reach the tip, STOP. Do not keep sweeping back. If you continue you’ll start changing the direction of the edge. This can give problems later with poor matching and gaps between the 2 blades when closed.
After you hit the tip start sweeping forward doing the same motion in reverse
Here is how I hold the tool when sharpen it.
Keep on repeating this motion until you get a burr. I’ll elaborate on this in part 4. Start working on the inside face now:
The inside bevel is flat so you can just do a back and forth motion. It’s imperative you keep it flush against the stone and match the angle. Mistakes here such as increasing the angle of the bevel face against the stone can make the edge more obtuse and greatly impact the cutting performance of your tool. I made that mistake while sharpening my Kaneshin cutters which is why I recommend going slow and checking your work. Keep on working until you’ve created a burr again. Switch to the opposite side to remove it. At this point I’d do alternating strokes between outside and inside bevel to ensure a crisp edge with no remaining burr.
After you’ve succesfully sharpened the edge or removed any chips switch to the overcutting blade. If you want to maintain the very slight overlap between the blades you’ll want to work both blades the same. Whether by number of strokes or simply by feel try not to sharpen one blade significantly more than the other.
Here is the Lee Valley cutter after finishing both blades.
Relatively clean union with little light escaping:
Part IV: Burrs and Finishing
If you did the stonework right the edge should be clean with no remaining burrs. I’ve given burrs it’s own part because it imperative that you make sure the edge is clean with no burrs.
If you cut a branch with a remaining burr your edge will roll over wasting your work. If a burr is present you can feel it. Run your finger off one side of the blade. Do so on the other. If one side is smooth and the other significantly more rough there is a burr. You can use a leather strop or even a piece of wood or plastic to remove it. Just sink the edge in something and pull across a few times.
Well that it! Hope it helped. If you did everything right your old concave cutter will be good as new! Maybe. I know there’s a lot of information in this article. Feel free to comment or message me questions. Sharpening concave cutters are fairly complex and was a learning process for me. I didn’t even do that good of job on my new Kaneshin cutters but I’m confident I can do an excellent job on any cutters in the future.
One piece of advise I’d give is use the right tool for the job. I’ve consistently cut branches much bigger than the cutters and have done root pruning with chunks of lava getting crushed between the blades. These led to issues like chips and misaligned tips. If you use the tools properly they’ll function for a long time. But if you ever get to the point you need to repair it, you have a resource now 😁.
In late 2016 I purchased a large variegated elm at a steal of a price. Within the thick canopy hid a region of significant inverse taper. Perhaps problematic but I immediately recognized the potential as a layer candidate. As a weaker ulmus parvifolia cultivar you don’t too many of em that has grown this big especially with such dramatic taper.
(missing progression pictures added)
Here’s a closer shot:
The large mid trunk bulge was likely produced through many years of pruning at the same node site. You can actually see a few old pruning scars on the trunk. At the time of acquisition it was mid summer in Southern California. Our growing season extends all the way to September giving me more than enough time to begin an air layer.
A common reason why airlayers fail is due to remaining cambium on the girdle. The brown exterior is the cambium while the immediate layers of wood underneath it is the xylem. When creating a girdle you forcibly prevent sugars in the cambium from returning to the roots. At the same time the wood underneath can still supply water and nutrients to the tree. Sugars and hormones build up at the cut site which over time generate new roots. If you mistakenly leave a strip of cambium the tree will actually heal or “bridge over” preventing the formation of roots. Airlayers always should be started after the leaves flush out and harden and take anywhere from 3 weeks to a year depending on species, age of wood, as well as the size of layer.
I neglected to take full progression shots but my layer medium is chopped spagnum and fine pumice. Chopping the spagnum in very small bits is important. It makes it a lot easier to remove the old spagnum in future repottings.
Here is the tree in fall. Another desirable feature of the hibari elm is the fall color. I’ve consistently seen the weaker variegated varieties producing nice fall color while their hearty landscape counter parts turn green to brown. It’s possibly the smaller amount of chlorophyll present in the leaves allow fall colors to emerge better.
The winter image. At this point I have not cut anything back. The more branches and growth I leave on the tree the faster it will grow new roots at the girdle site.
The layer was severed around May if I recall right. It took around 6 months to complete this layer. Another important note is that unless you live in a mild climate like me with no freezes do not layer if it won’t be finished before winter. Freezes will kill the new fleshy roots forcing you start over in the spring.
The tree was transplanted into a pond basket and had several primary branches cut back. It grew very well and was exceeding healthy in the spring.
Unfortunately this summer I was unable to personally care for my trees when I moved near Chicago for work. From a watering issue, disease, or pest the tree dropped all of its leaves mid summer. Fortunately it rebounded back but I did lose some low primary branches.
I repotted the tree recently and was happy to find a lot of roots. I did some minor cleaning but did minimal pruning.
I screwed the tree to a piece of plywood prior to repotting. This encourages the tree to focus on lateral root growth producing a better nebari. Ideally I would want to clean the roots completely and put them flush against the board but given its weak state I do not want to risk the tree dying. As an older piece of material with high potential to be an excellent tree in the future health is the main concern.
Decent mat of roots. Black regions are actually some dead roots which correspond to the branches that died.
Some of the main trunk has died back but there is plenty enough green for new buds to rebuild lower branches from.
Repotted and rigged to my water system. Underneath the wooden board I used almost entirely 3/8ths lava. On the sides and top I used my standard bonsai mix with a little bark added. My soil is one part lava, one part pumice, and one part diatomaceous earth. I’d like to cut back but the tree is not strong enough. I will allow it to grow relatively unrestricted to rebuild strength before significant work.
Assuming a strong growing season next year I’ll really work the roots and begin building the nebari. There are actually many usable surface roots that in time will build the base of the tree.
On a different note I still have the lower half and will be using it to grow cuttings. Later this year I’ll he selling cuttings from the hibari elm and possibly other nice hard to find varieties. Be on the lookout.