Turning marks ... I think

Signed-In Members Don't See This Ad
N

Natator

Member
Joined
Nov 19, 2018
Messages
3
Location
Brisbane
Greetings all :)

Periodically I get marks on my pens that I think are turning marks, but I'm not sure. The attached photo shows a typical example. They aren't actually as obvious as they look in the photo, I had to mess around a little with the light to "enhance" them.

The reason I'm not absolutely certain if they're turning marks is that they are at an angle. I turn fast (now) and shave the wood gently, but can't see how that motion causes marks at that angle. However, I can't think what else they could be. Doesn't happen often but is really annoying when it does. Some woods, like with the olive here, seem more susceptible than others I think. Also, these can't be seen at all until I start to apply the CA, or something like an alcohol clean before that evaporates. Sanding doesn't seem to help either, and they can't actually be felt.

Thoughts and any advice? I'm a bit lost on this one.

Thanks :)
 

Attachments

  • IMG_3613.jpg
    IMG_3613.jpg
    464.4 KB · Views: 256
Signed-In Members Don't See This Ad
I'm pretty sure what you are experiencing is called Chatoyance. It is where the grain patterns reflect light. One will pay extra for woods (maple, Cherry, Walnut, etc) with this chatoyance. Often referred to as curly maple, curly cherry, etc.
Your sanding and finish are fine!
 
2 Possible Reasons:

1. I used to get that more with olive wood than other woods but it does happen with some other woods. WHY it does that, I don't know, but here is HOW it happens for me (meaning I can repeat and duplicate it):

Finish sanding and apply a few light coats of thin CA. Sand the blank and sand through the CA in spots to the wood, re-cover with CA. The spots that you did NOT sand through will be darker than the lighter bands with fresher CA.

In my case, It occurs when I thoroughly coat the olive wood in CA and let it set for a few hours or overnight, and then when sanding down and sanding through the CA.

There was one more aspect that I learned that was related for me. Your pattern is circular. Are you holding the sandpaper with your fingers and kinda squeezing it? That would indicate why you have striations where you grip with your fingers. For me, I was using a mandrel and had minute' "out of roundness" [OOR] to it (OOR, not the technically correct term, but you get the meaning) The high spots on my blank were sanded through to the wood and after re-applying CA, it would show up as a light spot.

2. That also looks like "splotches" that I get on pine when I make shelves or other things with soft pine. Since that is not pine, - what grit sandpaper are you using to sand the blank? Wet sanding with course SP and not letting it dry completely can exasperate the issue by raising the nap which can cause splotching - light spots and dark spots on light wood.


Edit in: I re-finish a number of my pens that I have given to family and friends. After taking them apart, I turn (with very light touches) ALL of the CA off and re-finish. If I leave a spot or two of CA, it will show up as darker than the new, and since I KNOW that, I make sure ALL of the CA is off. I don't like using acetone to remove the old CA as it doesn't do as well or consistent - as turning the old CA off before adding a new finish.
 
Last edited:
Dieseldoc said:
From what I'm seeing it looks like sand paper burn marks. Using old paper that is clogged will make marks look like burning. Look at left side of blank and you can see paper marks and burning.
Click to expand...

Not clogged paper. I'm a bit OCD about the little bits of sandpaper, always use a new square (or half of a square) on every blank.

Thanks, also, to everyone else. It's actually a big relief it wasn't my doing as I couldn't for the life of me what it was if it was me. I also admit I was paranoid that if another pen turner saw that they'd think I was hopeless.

Hank, I'll reply to your post below :)
 
Firstly, thanks for the welcome. Long term listener, first time caller ;)

leehljp said:
2 Possible Reasons:

1. I used to get that more with olive wood than other woods but it does happen with some other woods. WHY it does that, I don't know, but here is HOW it happens for me (meaning I can repeat and duplicate it):

Finish sanding and apply a few light coats of thin CA. Sand the blank and sand through the CA in spots to the wood, re-cover with CA. The spots that you did NOT sand through will be darker than the lighter bands with fresher CA.

In my case, It occurs when I thoroughly coat the olive wood in CA and let it set for a few hours or overnight, and then when sanding down and sanding through the CA.

There was one more aspect that I learned that was related for me. Your pattern is circular. Are you holding the sandpaper with your fingers and kinda squeezing it? That would indicate why you have striations where you grip with your fingers. For me, I was using a mandrel and had minute' "out of roundness" [OOR] to it (OOR, not the technically correct term, but you get the meaning) The high spots on my blank were sanded through to the wood and after re-applying CA, it would show up as a light spot.
Click to expand...

That's really great advice about the CA and I'll definitely keep that in mind. Wasn't the case here as no sanding done until all the CA layers were completed.

I was indeed holding the papers with my fingers, but I also don't believe that was what was happening. If the marks were perpendicular then that might cause it but these were at a definite angle, as I've had in a couple of other pens as well. Not sure what rpm I was sanding at, I'd need to check lathe specs, but it would certainly be too faast for that much horizontal movement. I also tend to sand pretty lightly.

leehljp said:
2. That also looks like "splotches" that I get on pine when I make shelves or other things with soft pine. Since that is not pine, - what grit sandpaper are you using to sand the blank? Wet sanding with course SP and not letting it dry completely can exasperate the issue by raising the nap which can cause splotching - light spots and dark spots on light wood.
Click to expand...

Prior to CA I usually go 400, 600, 800, though I often skip the 600. Occasionally I'll start with a 240, but that depends on the wood and how it's ended up after the main turning. Then on goes the CA. This is usually x2 with thin to start. Sometimes I apply this with BLO but usually only on the darker woods as I don't like the yellow tinge it gives the light ones. Then x9 of medium CA. Why exactly 9? The way I fold the kitchen paper I use to apply it makes one strip suitable for 3 little applications. Somewhere along the line I decided x6 wasn't quite enough and 12 was overkill. I then attack it with micromesh, used wet.

There are situalktion where that might vary, but that's my basic approach.

[/QUOTE]

Thanks for going to so much trouble to apply there, it is really appreciated!
 
You must log in or register to reply here.
Back
Top Bottom