The wood bowl turning trouble zone is a dirty little secret seems to mention. It is a very real wood surface issue that occurs on almost every turned bowl and must be addressed.
Both the outside and the inside of a wood bowl turning have two locations each where tear can occur, even if all other bowl gouge techniques and skills are being performed flawlessly.
This is the area I’m calling the wood bowl turning trouble zone, or perhaps more appropriately – a wood bowl turning dirty little secret.
I must admit, it took me a long time to realize this turning trouble zone even exists and why it happens. Part of the reason was I needed to hone my bowl gouge skills, so any lack of tool control wasn’t the more significant contributing issue.
Once I was able to consistently make clean, bevel riding, grain-supported cuts, there was still a particular area where marks remained.
Let me be clear, you must understand and be able to execute a bevel riding or bevel supported cut, almost with your eyes closed first. If you need to fine-tune your bevel riding skills, stop now and read this article, Bowl Gouge Bevel Riding.
Without riding the bevel of the bowl gouge, cuts on the bowl will most likely leave noticeable tool marks. Learning how to remove tool marks is a whole different topic.
With The Grain
Another skill that must be addressed is the ability to understand the grain direction.
Many people want to call this “cutting with the grain” which makes little sense as the wood grain is sideways and spinning. I go into this in more detail in my Bowl Gouge Supported Cut article, please read it now if you have any doubts.
In a nutshell, the layer of wood fibers that are being turned needs to have longer grain fibers underneath each layer of wood fiber to support the pressure of the bowl gouge as it progresses and makes each cut.
When the cutting process is performed in the wrong direction the fibers being cut do not have supporting longer wood fibers underneath, so they break off and tear when the bowl gouge passes.
Wood Bowl Turning Rotation
A side-grain oriented wood bowl turning is a rotating bundle of linear fibers that spin end over end, from end-grain to side-grain to end-grain and so on.
It’s always that dreaded end-grain that gives us wood bowl turners fits. The side-grain is a piece of cake and cuts beautifully with little effort.
The end-grain is where all the trouble resides.
As the bundle of wood fibers rotates, the end-grain is presented to the bowl gouge. How the bowl gouge is angled and directed are two factors that determine how the end-grain will look.
End-grain tear out is a huge issue that can affect any turner at any time. If you struggle with tear out, you may find a remedy by reading 14 Ways To Avoid Grain Tear Out.
Some tree species are more prone to tear out than others, but all wood end-grain will tear out with improper bowl gouge skills.
Wood Bowl Turning Trouble Zone Location
So this is where the dilemma kicked in and how I discovered this wood bowl turning trouble zone area.
As I was sanding a bowl on the lathe, I realized there were tear out marks on the inside of the bowl that needed to be sanded. At first, this wasn’t a big deal because in my early days of turning pretty much everything required sanding after turning. Lots of sanding.
But things are different now. I went through my mental checklist, and I had sharpened the bowl gouge before the last passes, I rode the bevel, and I was making grain-supported cuts.
We need to go back to that visual of the bundle of wood fibers, or straws that is the bowl blank and take a closer look.
End-Grain Close Up
If we look closely at the fiber structure of a turned bowl and begin to think what’s happening, we can see the trouble.
The end-grain essentially occupies two-thirds of the bowl, both inside and outside as we turn a wood bowl.
Look closer now. The end-grain is positioned in such a way that a mass of parallel fibers rotates past the bowl gouge from left to right. The orientation of those parallel fibers is different when they first engage the bowl gouge compared to when they leave the cut.
Dirty Little Secret
The dirty little secret about wood bowl turning is that riding the bevel and grain supported cuts are the only things we can really control.
Granted, riding the bevel and cutting with grain support are essential skills to master in the process of learning how to turn a wood bowl, but there is more at play inside the bowl.
As we focus our attention on the cutting point of the bowl gouge, we can not escape cutting against the fiber grain direction.
Yes, you read that correctly.
It is impossible to cut all wood bowl fibers perfectly clean. There is no such thing as a perfect cut on the lathe with a side-grain oriented bowl blank.
That is the dirty little secret and why there can be end-grain marks even when a cutting pass is made by the book on a wood bowl.
Wood Bowl Turning Trouble Zone Explained
Regardless of the rotating direction of the wood bowl blank or the cutting direction of the bowl gouge, there will always be end-grain fibers that are cut “incorrectly” and potentially break off.
If you’ve read any of my other articles you know, I like to qualify my statements and for a good reason.
Every wood is different for their countless characteristics. Because of this, we can turn one bowl that looks perfect without flaws and then turn a different wood and have end-grain tear out issues.
A great example that I’ve turned lately is black cherry and spalted pecan. The cherry turns and looks like beautiful polished marble when done. On the other hand, the spalted pecan presents the trouble zone tear out marks almost every time.
What is happening is the fibers are weaker and tear easier with the pecan. Streaks and marks form precisely in the trouble zone.
As the fibers come around, the first end-grain fibers are coming straight into the cutting edge of the bowl gouge and unsupported by longer underlying fibers. This is where the impact and tearing occurs.
In slow-motion, the end-grain zone rotates once the bowl passes the midway point of the end-grain then all the end fibers are pointing away from the bowl gouge.
With the fibers pointing away, they get cut cleanly and have no troubles. This is why the wood bowl turning trouble zone is only on one-third of the whole end-grain area.
Wood Bowl Turning Trouble Zone Test
Here’s a great way to determine if the marks are from this notorious trouble zone or from poor bowl gouge control in general.
First off, as described above, the tear out should only appear on one-half of the total end-grain area.
Now, the real test. Find the tear out area and then rotate the bowl 180 degrees. Is there another, almost identical marked up area on the opposite side?
If yes, then you have found yourself in the wood bowl turning trouble zone. Cue the Twilight Zone theme music now.
Also, look around the rim and check the bowl exterior. Do you see similar marks on the end-grain and opposite areas?
Wood Bowl Trouble Zone Locations
Because the end-grain areas are located at each end, they occupy one-quarter of the bowl diameter each. The wood bowl turning trouble zones are only in about a third of each of these areas.
Therefore the trouble zones are each about an eighth of the total diameter, twice on the inside and outside.
If your lathe is rotating forward (over the top and down) and you are positioned with the headstock to your left side, the wood bowl outside trouble zone areas is located on the trailing side of the end-grain.
The inside wood bowl trouble zone marks will be located on the leading edge of the end-grain areas.
Trouble Zone Solutions
If you’re only finding issues in the wood bowl turning trouble zone and nowhere else, here is the good and the bad news.
Let’s start with the bad.
The trouble zone end-grain tear out and marks still need to be addressed.
The great news is that you’re rocking your bowl gouge bevel riding and supported grain cutting skills.
When you get to the last pass or two on both the outside and inside of the wood bowl stop and sharpen your bowl gouge.
Also, consider using a smaller half-inch finishing gouge, if you’re not already.
Sharpen the gouge slowly and carefully, like a surgeon going to operate.
Slow and Thin
Slow down your cutting pass and give the bowl gouge time to make the cut.
Remember we are dealing with the tips of fine tightly packed wood fibers and they break easily.
Deep cutting passes have a tendency to rip and tear out the fibers we’re trying to preserve. Make slow very thin, light passes to achieve a smoother surface.
Bowl Gouges Can Be A Heel
The sharp bowl gouge is the best tool to produce a clean, crisp final bowl surface.
However, if the inside angle of the bowl is tight or too much pressure is applied, the bowl gouge heel can burnish the wood surface and leave marks.
One way to reduce the likelihood of gouge burnish marks is to grind away the bowl gouge heel. At the grinder, after applying a sharp bevel edge, move the gouge forward so only the heel contacts the wheel. Roll the gouge back and forth until the heel is smooth and rounded back.
Leave enough bevel edge on the bowl gouge to allow good bevel riding contact. You may be surprised how narrow the bevel can be and still work perfectly.
Scrape The Way
If all else is not working or you have a tightly curved location, try using a round nose scraper.
This can be a regular scraper or a negative rack scraper. I would recommend a burnishing tool to apply a cutting burr to the scraper edge.
With a burr applied, the round nose scraper can make cleaner cuts versus scraping passes on the bowl surface.
Again, make super light, thin passes and work slow. Only the tips of the damaged fibers need to be turned away smoothly to reveal an overall clean surface.
Sand Those Spots
Sanding is another way to remove these marks, but it can be stubborn at times. End-grain does not sand well in general.
Do not try to sand away the trouble areas with the lathe rotating. The trouble zone areas will only persist.
Instead, focus your sanding only on the trouble zone areas with the lathe off. I use the side of a three-inch sanding pad and position it with the grain of the wood.
If you sand with the pad fully engaged, swirl marks will form. Just sand with the right edge of the sanding pad.
Also, sanding against the grain lines (completely different from turning with the grain or supported grain cuts) will result in scratches perpendicular to the wood grain.
Work the edge of the sanding pad along the wood grain lines in the trouble zone until the marks disappear.
If the marks persist, step down a grit of sandpaper. If 120 grit isn’t removing the turning trouble zone marks, try 80 grit.
Once the mark is removed, work back up the higher grits of sandpaper working with the grain in the same manner.
Work Bowl Turning Trouble Zone Conclusion
The work bowl trouble zone is a very real dirty little secret that can affect even the most seasoned veteran wood bowl turner. Knowing what it is and how it works is the key to addressing any problem.
Hopefully, this article helps you see where the issue lies and how to address it, if and when it appears.
Perhaps this is what makes wood bowl turning so fun. Even after mastering the bevel riding and supported grain cuts there can still be issues that seem perplexing.
Figuring out these issues and solving them is almost as satisfying as watching a movie and eating popcorn from a beautiful wood turned bowl you made.
Something tells me, there will never be an end to the things learned and the satisfaction gained while turning wood bowls!
BONUS: Glenn addressed the Trouble Zone issue in a slightly different way, check out what I learned from Glenn Lucas in this article.