How well do segmented bowls stand the test of time......?

[Doug Rasmussen]

With different woods and grain orientations does normal expansion and contraction of the segments with seasonal changes in humidity cause the bowls to have a rough surface over time? It seems there might be movement at the glue lines of segments.

Never having touched or handled a segmented bowl this is something I've wondered about. In our 1920 home with original hardwood floors we see quite a difference in the squeak of the floors between winter and summer due to change in humidity and that's with the same wood and grain orientation.

[Grant Wilkinson]

I'm sure that others will have longer-lived bowls, but mine of 5 years or so all all still smooth and tight. There could well be a lot of luck coming into play here, but so far, so good.

[Doug Hepler]

Doug,

I have made segmented turnings for more than ten years. A year ago I moved some from coastal Florida to Golden CO. I have not noticed any significant issues. I use wood of identical dryness (air-dried or KD, not green or wet). Regarding grain direction and glue joints, the end grain to end grain rings are strong enough to withstand flattening, etc. When the vessel has been assembled, the overlapping segments are long grain to long grain. My segments are usually 3/4" or less thick so expansion/contraction is not a problem. I seldom make segments thicker than 1 1/2". If I want thicker segments I use staves (beveled along the long grain).

Doug

[Doug Rasmussen]

Grant & Doug, thanks for the replies. This is good to know since I've been thinking about segmenting.

What glue do you use?

[Doug Hepler]

Doug,

Usually PVA (Titebond II). I assemble rings on waxed melamine board or on plywood covered with waxed paper. I clamp with steel band clamps (like large hose clamps). Squeezeout is not an issue because the rings have to be flattened and will eventually be turned.

Doug

[Michelle Rich]

legitimate question, and depending on skill and luck, it may or may or may not have issues. Large platters seem to be the worst. Small bowls, seem to be better. The real issue has been "glue creep". The yellow glues are not rigid. When the woods start to expand the glue "creeps" with the wood. When the wood contracts, the glue may not creep all the way back, thus leaving the ridge of glue one feels at the joints. I have returned some bowls to the lathe and resanded , and that has worked 9 times out of 10.

[Doug Rasmussen]

legitimate question, and depending on skill and luck, it may or may or may not have issues. Large platters seem to be the worst. Small bowls, seem to be better. The real issue has been "glue creep". The yellow glues are not rigid. When the woods start to expand the glue "creeps" with the wood. When the wood contracts, the glue may not creep all the way back, thus leaving the ridge of glue one feels at the joints. I have returned some bowls to the lathe and resanded , and that has worked 9 times out of 10.

Yeah, this what I was concerned about. Thanks for confirming my concern.

Elsewhere I read about glue creep. It was regarding PVA type glues for bent lamination glue ups. The author recommended the old water mix powder Weldwood plastic resin glue since it doesn't creep under stress.

BTW: Weldwood plastic resin glue is getting hard to find. Maybe the long cure time and worries about the formaldehyde content?

[Brian Brown]

When I started segmenting, I had a problem with rough edges between segments. I could feel the joints. It was frustrating because I would assemble, turn, and sand the piece, and everything seemed perfect. Very smooth tight joints. Then a few weeks later I would pick up the piece, and the joints would be rough. I blamed it on changes in temperature and humidity. The thing is I live in a very arid climate. There is not a lot of humidity change here. I found the solution by accident, when my turning time became very limited. When I did a glue-up, turned, and sanded all in a short time, the joints were rough. When time became a problem, I would do a glue-up, and it might be a month or more before I got to turning and finishing. I had less problem with rough joints. I figured out that because the glues have water in them, the surrounding wood absorbs the water and swells. When turned immediately, the cut fits the swollen wood, and as it dries and shrinks the wood gets smaller leaving the glue poking out slightly. Different species can swell and shrink different amounts, so there is no consistency. Being forced to wait long periods to complete the project allowed the water to evaporate and the wood to stabilize prior to turning. It is not necessary to wait months, but maybe a week or more, depending on your humidity. As for joint/glue stability over time, I think it depends on the quality of your original joint. Tight tolerances and clean surfaces cause a better glue up. While a lot of skill and care are involved in long term stability, I think good luck is just as important as skill. I don't think I have had any joint failures, but now I have to go look at my segmented stuff and see.

[John Nordyke]

I, too, have segmented vessels more than 10 years old now...I have not had problems with the creep among segments. I have noticed, however, that the inevitable color fade/darkening of different species of wood and finishes over time leads to some objects becoming, frankly, less attractive...either a loss of contrast, or uncomplimentary colors.