Segments move under CA?

[HopeAndGracePens]

Have a very specific issue. Searched some threads but no luck (please link if answered already). Sometimes with segmented pens, the seams become pronounced to the eye and/or touch with a CA finish. This happens over days/weeks/months, so assume it's humidity expanding/contracting the wood at different rates due to species.
Segmented turners, how do you overcome this?
Is there a finish that is both durable and will prevent this?

 

[jttheclockman]

You will have to explain what we are looking at. I will have to say never happened to me and will never happen. Unless you are using pourous materials and papers and wood may present a problem. Cloth and woods can present a problem but find it hard to believe. Metals and woods will not. Acrylics and woods will not acrylics and metals will not.

 

[HopeAndGracePens]

Thanks, @jttheclockman. The pens in the images are both segmented pens I've made that show this flaw. If you enlarge the image, you'll see a sort of white fuzziness, discoloration or actually see the 'bump' at the seams where one wood type meets another. The one on the right is American cherry and hickory showing the fuzziness. The one on the left, you can actually feel sharp ridges at every seam. Thick CA and clamps were used to join the woods and on the brass tubes. After turning, both received tung oil wiped away after 15 min, then allowed to cure overnight (if not longer). I used thin CA in at least 9 layers for finish, micro-meshed to a nice gloss and then topped off with plastic polish. At the time these were made, neither had a flaw or blemish in the finish. These flaws developed over time and all are wood-on-wood.

Now I'm ready to finish a nice herringbone I'm making for a friend, but am afraid that in a year these problems will appear. I can't be the only one to experience this! Is there some product or technique to prevent it?

 

[Mortalis]

What was the wait time from segment glueup to turning?

 

[mark james]

Yes, I have had these issues also. I do not sell, so no complaints . But for the few that I still have in my possession, after 2-3 years some have a noticeable "bump" in the segmented joints. I notice this with both a CA finish and WOP.

I suspect it has to do with end grain and side grain not being aligned, as well as simply different timbers with different densities. I prefer to have ALL end grain going from the finial to the nib. And all side grain on the sides of the blank.

My preferred finish with segments is WOP. Just a bit of flex.

 

[Sylvanite]

See https://www.penturners.org/threads/does-your-ca-do-this-i-think-not.133393/page-2#post-1778258.

 

[HopeAndGracePens]

What was the wait time from segment glueup to turning?

These were both done years ago, so it's impossible to remember accurately. It would be a minimum of 22 hours, likely more. Possibly days.

 

[KenB259]

It has happened to me one time. The one and only herringbone pen I made. I got a little to aggressive with micro mesh and sanded through the finish in a few places. I was wet sanding and all that end grain sucked up a little water. That in turn caused some swelling and ended up with some pronounced seams. The second pen you show, to my eye, doesn't even look like it has a finish on it. Don't take offense to that, it might just be the photo, but the finishes on both your pens looks very different.


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[jttheclockman]

Well there is no hiding the fact that wood does move and moves differently end to end or side to side. Then throw in the different types of wood used will add to the problems. I will have no answers for you but will suggest stop using CA as the adhesive for wood to woods. Use a wood glue designed for wood. Woods turned down this thin should not move that much. Having said that woods need to be dry when working with. I have never had a problem like this with segmenting of woods. I avoid adding oils and then top coating. I also seal my woods with 3 coats of thin CA and then top coat 4 to 5 coats of med CA which is thicker. I allow for this when I turn it down. Maybe other who have done herringbone pens will weigh in because there you are alternating grains. Maybe do it in all acrylics and eliminate the woods. Good luck.

 

[mark james]

I really believe the "fuzzyness" in the second blank, grey/white edges is endgrain. Different absorbtion of a finish, different expansion/shrinking, different appearance than side grain.

 

[leehljp]

As John said, MOST Wood Moves. Period. There are books on this. The particular cut of wood determines how much it will expand or contract. A few woods do not move much. Mesquite is one of those.

Stabilizing cuts down on some expansion/contraction; drying wet wood down to 5% and less before using in a pen. But different woods expand and contract at different rates exacerbating the problem when used together in segments. High humidity swings affect this too. A humidity controlled environment helps.

The fact that pens are so small, while it is noticeable, it doesn't show up as much as in furniture.

 

[KenB259]

I really believe the "fuzzyness" in the second blank, grey/white edges is endgrain. Different absorbtion of a finish, different expansion/shrinking, different appearance than side grain.

You're probably right, it's vey hard to tell.


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[MillerTurnings]

In the segmenting world, and the furniture type world, this is commonly known as "glue creep". Googling will yield lots of different causes and cures for it, admittedly some appear to be guesses. There are so many factors involved, I don't see one "fit all" cure. I know that some of my segmented bowls will show this after a few years, others do not. It is all part of the "hand crafted" world, and doesn't appear to bother the art crowd.

 

[HopeAndGracePens]

This is quite an education. Knew I'd come to the right place.
Thanks to all for contributing. Your input is invaluable. @Sylvanite , This comment from 5 YEARS AGO on a thread here on IAP contains something I can do or at least strive for to reduce this effect:

"When wood expands and contracts with changes in temperature and humidity, it typically moves more in the direction of the grain than perpendicular to it. Therefore, if your segmentation shows both face-grain and end-grain, then when the woods expand, the end-grain will become proud of the face grain. I've noticed that happening even when using regular non-flexible CA glue for the segmentation. Such movement also tends to fracture the finish at the glue lines.

I've taken to cutting wood segments so that the grain runs longitudinally to the pen axis for all the pieces. That way, they all tend to move most in the same direction. This minimizes the effect (but doesn't eliminate it entirely, as different types of wood still expand and contract at different rates)."

I wonder now, with five years' additional perspective, has experience affirmed your technique?

 

[leehljp]

When I lived in Japan, there was another fellow there in the Shizuoka area that made pens and sold them. He made a few with cross cut blanks and put them in a glassed in counter. Sun came through the windows and into the glassed counter. Large "spaced cracks" in the blanks to the extent of being able to see the tubes - occurred. Most woods will move proportionally more on cross cut than straight grain length.

Wood moves in three ways on a single board and different percentages each way: Length, width, thickness.

The variables:
• Wood type
• Wood cut: cross cut, angle cut, along the length of grain - Or Along: Length along the grain, Width (across the board/side to side), Thickness (inside to outside)
• Humidity swings
• Heat/Cold -Temperature swings

THEN there are veneers. Veneers do not move like the same wood in a board. Veneers are flat sheets of 1/8 inch or less, and usually less that are laminated onto other layers. I mention this because "wood movement" does behave differently in specific situations (laminates) as a opposed to normal situations.

 

[mick]

I've actually noticed on a couple of segmented pens I made years ago(read 10 yrs ) shrinkage of CA glue at a joint line or in one case shrinkage over a patch of crushed turquoise stone. Other than that I've never had it happen.

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[JoeCallahan]

This is not a "cure all" solution, but it's definitely improved the durability and longevity of CA finishes on my segmented pens.

Firstly, before I glue in my brass tube, I flood the inside of the drilled blank with thin CA to be sure that all the inside surfaces are sealed. Then, once the blank is turned and sanded, i use some non-stick cone bushings to apply my finish. The shape of the bushings allows me to coat the ends of my blank that are normally covered by the steel bushings. Having all surfaces, inside and out, sealed with CA drastically reduces the likelihood of wood movement due to humidity. I also make sure to use a flexible CA to further increase my odds of success. GluBoost is my personal preference.

-Joe

Non-stick cone bushings: https://www.exoticblanks.com/bushings-for-ca-glue-finishing-set-of-4-hdpe.html