Moderators: Random Orbital Bob, nev, CHJ, Noel, Charley

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By transatlantic
#1266184
What causes these streaks? I know it looks like torn grain, but when I look very closely, it doesn't actually look torn. It's as smooth as the material surrounding it. It just appears to look lighter? It also doesn't seem to sand out. I spent a good 5 minutes with 120 and it looks pretty much the same after.

- It doesn't go all the way around. It fades away on about 30% of it
- The grain doesn't appear to change direction at that point
- it's the same cut from the base to the tip of the bowl (I didn't stop/start half way through)

So is it torn grain? or something else?
Attachments
20190203_171648.jpg
By Qweel
#1266208
Oooo that'd be Brexit...Ahh the impacts of brexit are everywhere .... ](*,)

Looks like oak, when i've had that i thought it was simply the orientation of the grain, but not sure in you case, doesn't look like the grain should be any different from the rest.

Nice bowl by the way.

Will
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By Bob Chapman
#1266325
These look like medulary rays which look like thin pale lines in end grain oak and wider irregular patterns on side grain. They are a natural feature of the wood and cannot be removed by sanding etc. they are very prominent in oak and are one of the features used to identify oak. Your finish looks excellent - just as it should!
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By Paul Hannaby
#1266331
Yes it is torn / bruised grain. It can go quite deep so takes an awful lot of sanding out. Either reach for the 60 grit or resharpen your gouge and take a couple more light finishing cuts to get a clean surface before sanding again.
By phil.p
#1266333
Bob Chapman wrote:These look like medulary rays which look like thin pale lines in end grain oak and wider irregular patterns on side grain. They are a natural feature of the wood and cannot be removed by sanding etc. they are very prominent in oak and are one of the features used to identify oak. Your finish looks excellent - just as it should!


It's not the rays he's asking about, it's the pale ring that the two red arrows point to.
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By Trevanion
#1266337
Paul Hannaby wrote:Yes it is torn / bruised grain. It can go quite deep so takes an awful lot of sanding out. Either reach for the 60 grit or resharpen your gouge and take a couple more light finishing cuts to get a clean surface before sanding again.


Dead on the money! I get this all the time because I'm a terrible turner. They do sand out after quite a while.
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By CHJ
#1266346
Looks like pulled grain (torn grain) to me, before re-cutting with very sharp tool, try moistening the Oak with water to swell the grain to encourage side support and provide lubrication.

If possible (depends on your gouge grind profile) make sure you are using the gouge cutting edge in a slicing action* rather than a straight shear (chopping) presentation in relation to grain and direction of rotation.
As Paul says it may be several millimetres deep.

* think in terms of carving meat as oposed to just trying to slice it by chopping with a knife.
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By Dalboy
#1266376
+1 for Paul Hannaby and CHJ's post above about torn grain.

Both remedies are very valid as well as water as CHJ's post try thinned cellulose sander sealer to support the fibres either of the three suggestions will work.
By learning to turn it out rather than sanding it will give you a better understanding of tool control
By Chris152
#1267055
That's nothing, transatlantic! I turned this bit of beech this morning.
_MG_8212.jpg

There was a little tearout, but it seems to be bruising - no texture, just a change in tone. Some part s of the same tree are fine to turn, others do this (tho this is the worst I've done so far). I don't really understand it. The shame is that I just left it as I was turning a few just to settle in to a new location for my lathe, and it turned out the inside was (I think) beautiful.
_MG_8209.jpg

The bruising coincides with areas that were really tricky to turn - uneven cutting, juddering - but I carried on with finer cuts and thought all was ok. I guess that caused the bruising, if it is indeed bruising?
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By CHJ
#1267161
Torn/pulled grain or compressed/bruised grain is something that catches everyone out from time to time and reminds you to re-evaluate turning methods, it's nearly always the innocent looking piece of wood that bites back.

Just occasionally though you will come across a piece that has odd shadows that won't turn out, frustrating when you've spent the last 10 mins chasing them before realisation dawns, can often be seen to be going full thickness through a bowl wall, whether they are the result of growing traumas or bending stresses during growth I've no idea but they can be very frustrating when they present the appearance of being the result of poor turning technique in the finished item.
By Chris152
#1267272
CHJ wrote:Torn/pulled grain or compressed/bruised grain is something that catches everyone out from time to time and reminds you to re-evaluate turning methods


Yep, and I did that this morning! I re-watched this video by Lyle Jamieson
https://www.youtube.com/watch?v=qnym1IyOPgE
and tried turning another from the same board, this time with the gouge slicing more (handle lower, and using more toward the wing than the tip) and sheer scraping rather than scraping in a more horizontal position and got what I consider a good result.
_MG_8214.jpg

Many thanks, Chas.