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I'm just beginning bowl turning and can't seem to avoid these deep blemishes in the exterior and interior of the bowl. Are these pockets naturally occurring in the wood or am I causing them through poor technique?

I have only used a Ellsworth Signature Bowl Gouge so far.

blemishes in bowl

  • This happened to me years ago when I attempted turning a log from my backyard. I never got in to turning, but my guess is that a sharper tool is needed. – Zak Feb 15 '16 at 0:58
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    This is what's called tearout and it's commonly seen when planing wood as well. There are a few ways to minimise or remove the problem using a plane but two of the main ones apply here as well — lighter cuts and ensuring your cutting edge is very sharp. Most good guides to turning I'm sure will address this issue as it's inherent to working all wood, so hit the books and see if there's other turning-specific advice given (which may include switching tools to take off the final 1mm or so). [contd] – Graphus Feb 15 '16 at 11:16
  • [contd] Assuming you get this and you're unable to get rid of all of it by turning or by sanding (for example you're down to your final dimensions already, or your walls are already thin and you don't want to risk the piece becoming too weak by thinning them any further) you can fill the defects left behind, just as is frequently done on flat boards. Commercial grain filler is the usual material for this, although there are numerous shop-made mixtures also used by some woodworkers, e.g a mix of fine sanding dust and varnish. – Graphus Feb 15 '16 at 11:22
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It's called Tearout.

That is tearing the fibers. Most of the time when you see that the fibers of the wood are tearing out instead of being cut/sheared by the gouges.

There are three thing that can cause this. One is the wood itself. Some species are a little more prone to this than others. Also wood that is starting to spalt or rot is more likely to do this as well.

It can be reduced quite a bit by technique. The more aggressive the cuts you make with the gouges the more likely it is going to tear vs. cut the fibers. So as you get closer to the finished shape you want (especially if you see this happening, the finer and gentler the cuts you want to make.

Also KEEP the Gouges SHARP. Sharper gouges are more likely to cut the fibers instead of pulling them out and causing this problem. It took me a while to figure these things out. (I also don't like how it looks most of the time and it takes FOREVER to sand them out once you make the mistake.

So, to reduce/eliminate this, when you see your piece is prone to this, make sure your gouges are sharp and if it continues, then take less aggressive cuts. I've done this to save bowls. I sharpen the gouge and then take very light cuts, it can 'erase' those big holes, at least to the point it doesn't take long to sand them out the rest of the way.

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    You've addressed how to deal with them They are called "tearout". – WhatRoughBeast Feb 15 '16 at 4:27
  • @WhatRoughBeast yep. Didn't have time to reread the question and my answer. I'll add that in. – bowlturner Feb 15 '16 at 14:04

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