Micro tear out?

[Mike Novak]

I have found that to get a good oil finish, I need to sand finer than 400. Problem I’m having is I’m getting micro tear out that I can’t see until I get to 800 or 1200. Then I need to go back to coarser grits. With a film finish it would disappear, but oil is less forgiving.

Any way to make this fine tear out more visible at 220 or 320?

Here is an example on the rim of this box lid.

 

[Randy Anderson]

Are you doing any sort of wipe down with mineral spirits or water in between grits? I always do a spirits wipe usually after 180 and again after 240 sometimes. Can show things that are not visible on dry wood. A water spritz also raises grain and can can help a lot in between grits to get a more consistent finish on fibers that have been pressed down by previous grits.

That said, there are times when after best efforts the application of oil will show something not visible before. It happens....

 

[Brian Gustin]

What Randy said, But your tear-out, looks to me to be tool marks , which I suspect with some practice and resharpening, could be eliminated before sanding - I used to get them endlessly, but then I discovered a freshly sharpened gouge with a "perfect" cut , eliminates that entirely, so now I know what to strive for, it saves a TON of sanding (Which , by the way, will show up those marks on a spinning piece under a raking light if you sand on the lathe, once you start getting into the higher 220+ grits)

 

[Randy Anderson]

Also, I'm a big fan of neg rake scrapers for dealing with very light/faint tool marks, refining a curve or dealing with compression marks. Not sure how you went about turning that lip but if you worked outside in with a gouge and then tilted the nose up very slightly when you got to the corner where the top goes up I would imagine the heel of your gouge making a nice compression ring right about where that place is.

 

[Ron Solfest]

As @Randy Anderson said, I suspect it’s not tear out but ‘bruising’, or compression from the heel of the gouge. I usually discover it after oiling a maple bowl and have gotten better at ‘floating’ the bevel and/or sanding in a suspect area more than appears necessary

 

[Lyle Jamieson]

No Matter what the cause, I think the answer is sharp tools. What is sandpaper but billions of sharp particles that cut cleanly. If you are using dull sandpaper(and it gets dull very quickly) you don't get the scratches out from previous grit. And many times it is hard to see until you put a finish on. Then you have to go back and start with fresh sharp sandpaper again, at the coarseness needed to get the scratches.

 

[robo hippy]

That looks to be an end grain turning. My finish cuts on the end grain boxes I make are always done with negative rake scrapers. I am getting to the point where 400 grit roughs up the surface. I agree that that mark would most likely be a tool mark rather than tear out. Natural spectrum lighting helps me the most, along with prescription glasses. I still have never done a wipe down with anything, other than maybe a dry rag.

robo hippy

 

[Mike Novak]

@Randy Anderson , that describes exactly how I made that rim, so maybe it is tool marks.

Thanks to everyone. Lots of good info. I have been trying to achieve the “perfect cut”. I’m still early in my turning journey, so I don’t always achieve it. I’m getting better. Too often I go back to touch up a cut and end up making things worse. I’ll get there.

That spot is end grain. In this case I thought I had a perfect cut. Started sand at 320 and didn’t see the problem until 400. I need to get better at seeing the problems before I start sanding. I will try moving the light around more and wiping it down.

It’s possible I might be trying to get too much out of a piece of sandpaper.

I’ll give a scraper a try on the next end grain piece.

Thanks again!

 

[Richard Coers]

Starting at 320 grit is a big mistake. I've been turning for 38 years, so it's not a matter of time before you should learn to turn well enough to do that.

 

[Randy Anderson]

I don't care how smooth and neat my surface looks after turning, I start at 120 or 180 to be sure. May not spend a lot of time with them before moving on but always a necessary step for me.