Dark rings on lighter woods

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rlkalish

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Jan 14, 2013
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3
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Bay Area, California
Every now and then when I am working with a lighter color wood blank, I get a dark ring on the wood near the bushings. I am not sure if I hit the bushing with my tool or if maybe the blank was not spinning as much as the bushing when I was cutting it. Anyone else seeing this or know what I am doing to cause it? I can't seem to sand it down because it seems to go all the way to the brass tube. I generally like to use Gorilla poly glue and do make sure the brass tube is inside the wood and use a barrel trimmer to cut the end flush...Any ideas would be great.
 
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JimB

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Mar 18, 2008
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West Henrietta, NY, USA.
It may be from the bushings either touching them with your tools or with sandpaper. It can also be on the bushing from the last time you turned or sanded. Try cleaning the bushings and your wood with DNA ( denatured alcohol). Wet a small piece of paper towel with the DNA and use it to clean the wood with the lathe running. Use paper towel, not a cloth.
 

Souths1der

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Jan 13, 2015
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SW Suburbs of Chicago
Could be heat related, some burn in from drilling. I had that happen a few times when I used to drill on my drill press. Doesn't show up until you turn it down because it only scorched the wood close to the drill bit. I drill on the lathe now with slower speed and better control and it hasn't happened.
 

MikeinSC

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Mar 10, 2014
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SC
Are you using a pen mill? If it's not sharp it will burnish the end grain making it darker.

I get this as well on denser woods. It does semem to be a bit of burnishing and also a bit of laid over grain all usually associated with a dulled pen mill.
 

Philip E

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Jul 19, 2015
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Location
Charlestown IN
I hope you all don't mind if I revive an old posting but I seem to have the opposite problem but the same problem. By that I mean I get the dark rings also but on dark woods. I was wondering if others had this problem and what they did to rid themselves of it. The rings never seem to appear until I get close to the finish size and as big as they are it seems unlikely to me that they are bleed over from bushings or burnishing from the pen mill.
 

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Skie_M

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Aug 7, 2015
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Lawton, Ok
Hey, I get rings like this even with sanding, but it's from using old nearly worn-out sandpaper! The heat buildup can cause a change in the wood coloration. This is most evident on woods that are sensitive to such changes, like purpleheart, maple, ect ... Maple turns a darkish brown to black ... purpleheart, unless you heat treat it yourself later, will have a spectacular purple shimmer deep inside the wood at the ends but will otherwise look black, especially in dim light indoors. I prefer to take a small blowtorch and heat treat my entire purpleheart blanks to get this appearance all the way through. It looks nearly black indoors, but when they take it outside it REALLY turns heads.


Almost forgot ... how do you fix it??? :)



If using a pen mill, make sure it's properly sharp, and that you're running it in forward gear. (I know, that sounds kinda stupid, but hey, it can happen! DAMHIKT)



When working on the lathe, make sure you're still rubbing the bevel with your lathe tools as you work, but remember that it really only takes LIGHT pressure to make your cuts. You don't want to burnish your wood with the bevel of your tool. Knocking the speed down a bit can help, but the best help you can do is to make sure your tools are razor sharp and properly maintained, and to polish the backs of your lathe tools so that the bevel creates as little heat from friction as possible.


Use fresh sandpaper for your sanding needs ... and a light touch rather than bearing down will yield best results... older paper will leave scorch marks, or even metallic or off-color wood residue behind in your work. Sandpaper isn't THAT expensive ... use fresh paper with every project unless you don't care about the final appearance. Also keep in mind when inlaying metals and stone in wood, you want CA EVERYWHERE ELSE so that the dust doesn't get into the wood while you work.

Micromesh is somewhat of an exception in this case ... you're only going to use it on acrylic or on a CA based finish, right? So it should NEVER touch anything but plastic... no issues there. You're also wet-sanding with it, so the residues are washed away.
 
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