Anyone have a warp do this?

[Odie]

I was working on a pre-seasoned bowl the other day, and left it on the lathe overnight. By the next morning, it has warped noticeably. This was disappointing, so I put it aside while I worked on something else. A few days later, I put it back on the lathe, and to my surprise, there was no longer any warp. That's great, but I don't recall this ever happening before.......

In my experience, when a bowl warps, the only way to bring it back to round is to turn it round again........

ko

 

[robo hippy]

If you have a finished bowl, and leave it in the dish water too long, it will warp. Take it out and dry slowly, and it will go back to 'pre-soak' size. Fine woodworking did an experiment about this with a block of wood. One was bolted to a plate on the bottom only. It expanded and went back to size. One was expanded, and bolted top and bottom, and when it dried, it split. The third was bolted on the bottom, but had a plate on top that was not bolted down. It was expanded into the top plate (adding moisture), and as it dried, it shrank to smaller than original size. I found that article pretty interesting.

So with your piece, yes, it could have 'adjusted' and they will do this even when 'totally dry'. When building furniture, you have to account for 'seasonal movement' or your piece will destroy itself...

robo hippy

 

[Raul McCai]

In every instance I've seen, when wood warps it never fully returns to the original shape. It can return but never completely.

 

[hockenbery]

This is unusual. Never had that happen to a dried bowl.
I check the MC of my dried bowls with a meter.

Do you know the MC of the bowl

Is it possible it somehow became off center on the lathe in one instance rather than warped?
Mabe it unscrewed a little when the lathe stoped or was never fully seated.
I have had that happen where something on the lathe threads gave the a tight feel but the chuck was not fully seated started getting a lot of wobble.

If the RH is fluctuating in your shop, two opposing changes in RH could possibly add/subtract moisture and then subtract/add the moisture in reverse.

 

[john lucas]

I turn dry wood mirrors. They often move just a little. I'm guessing it's due to stress relief in the wood. They move seasonably just like box lids. maybe your bowl picked up a lot of moisture somehow and then lost it later. did it rain a lot before you it warped.

 

[Odie]

This is unusual. Never had that happen to a dried bowl.
I check the MC of my dried bowls with a meter.

Do you know the MC of the bowl

Is it possible it somehow became off center on the lathe in one instance rather than warped?
Mabe it unscrewed a little when the lathe stoped or was never fully seated.
I have had that happen where something on the lathe threads gave the a tight feel but the chuck was not fully seated started getting a lot of wobble.

If the RH is fluctuating in your shop, two opposing changes in RH could possibly add/subtract moisture and then subtract/add the moisture in reverse.

I turn dry wood mirrors. They often move just a little. I'm guessing it's due to stress relief in the wood. They move seasonably just like box lids. maybe your bowl picked up a lot of moisture somehow and then lost it later. did it rain a lot before you it warped.

Al and John......I am equally surprised that a warp occurred, and then returned back to round. I don't recall this ever happening before. You raise some possibilities that could account for this unusual occurrence. We had both rain and snow here several times in the past week, so that could have influenced this. The shop is heated, and well insulated, but this time of year, I turn off the heat overnight. It hasn't gotten below freezing in the shop during this time. When I'm in the shop, it's around 65°, and it cools to the upper thirties overnight. Outside at night, it's in the mid twenties.

I doubt that the bowl moved on the face plate, but since it's a screw center face plate, that is always a possibility. It was without a warp when I retired for the night, and I left it on the lathe overnight. The next morning, I turned on the lathe, and it was warped. I took it off the lathe, and set it aside for a few days.....then remounted it and found that it had returned to round. The bowl was finished except for the foot, and is still mounted to the face plate at this time.

Off hand, I can't remember what the MC was.....will have to check my notes, and get back to you tomorrow on that......

ko

 

[Odie]

Off hand, I can't remember what the MC was.....will have to check my notes, and get back to you tomorrow on that......

OK, here's the bowl in question that warped, and returned to round after a couple of days. The size is 12"x4", and was originally 34% MC. Roughed, and after 12 months, it stabilized in weight. I did not use a meter after it stabilized, but I suspect it was around 12-14% after it did.

Not sure if we can pinpoint the reason for the warp, and re-warp from this information, but maybe someone else can make some sense of it.

I did my monthly weights today of those 35+ bowls I have in the seasoning process. Although most of them did continue to lose weight, I did have several that gained 5-10 grams during the past month.....maybe that is of some significance here......dunno.

ko

 

[Bill Boehme]

I have a bunch of figured maple blanks and also observed that the final weight will fluctuate by a few grams well after they have "stabilized". Of course we're talking about a blank that may initially have weighed several hundred grams so a few grams doesn't mean much. It seems like the ones that are softer and with lots of figure are the ones that show the largest fluctuations in weight.

 

[Scott Hayes]

I recenty did a piece of poplar that was not completely dry. I decided to finish it anyway with some linseed oil and paste wax. After a few days on the dining table I noticed a few small cracks appearing on the outside. I stuck it in a paper bag and a few days later the cracks had closed back up. It still warped out of round a little, but the cracks have not opened again. I did not know wood could crack and return.

 

[Gretch Flo]

I have seen this a number of times, and was discussed on this forum a couple of years ago. The problem is will they open up again once dry, and go thru the annular seasonal humidity cycles??? I questioned that if Super glue was used initially, would it prevent this "natural closing"?
My problem with answering this, is that bowls are stored in plastic tubs or are sold and what ones did this to look at later?????

 

[Bill Boehme]

I recenty did a piece of poplar that was not completely dry. I decided to finish it anyway with some linseed oil and paste wax. After a few days on the dining table I noticed a few small cracks appearing on the outside. I stuck it in a paper bag and a few days later the cracks had closed back up. It still warped out of round a little, but the cracks have not opened again. I did not know wood could crack and return.

That's not uncommon. An old woodturners trick is to mist the wood if cracks start to appear and wrap it in plastic for awhile to rehydrate. The important thing to recognize is that the crack didn't heal just because it closed. It's still there just waiting for the least convenient opportunity to open up again.

 

[Nicholas Licata]

I have had an idea that I've been meaning to try. I want to soak a square blank and then compress it in a hydraulic press and let it dry. Then round the blank and turn a bowl and finally put the bowl back in water and let it relax again. Has anyone ever tried this?

 

[Leo Van Der Loo]

Odie what I have had happen was some partially dry Hickory bowls warp so much that I was sure I would not be able to return them, I had kept the walls at about 8% as that is enough most times.

What I did not know at that time was that Hickory is one of these woods that move more than most, anyway I did not throw them out, but placed them up high on a shelf, and out of eye out of hearth they stayed there for many years, now moving up to our new place here they got placed in with the other smaller bowls, then last year I picked one up and measured it, now it was round enough to be able to return it, so I was kind of doubting myself, in that I did not measure it right “Then”, Icould believe that with one piece, but I turned several, so my thoughts are that over time, (more than 15 years at least) the tension in the wood did make the bowls move to the more round shape they where turned into when turned initially, BUT I’m still not sure.

With your bowl, would the heat from returning it to round, and then sitting in your shop that (Guess here) temp and bowl cooled off overnight, and therefore with the humidity going up the bowl did get oval.

So as you found it oval and set it away, it then got time to dry and get warmer equally, with the outcome of going back to round, maybe far fetched, but I do wonder the affect of these forces that do occur like that, ?????????

Than the other ????, are you sure it did happen

 

[Leo Van Der Loo]

I have seen this a number of times, and was discussed on this forum a couple of years ago. The problem is will they open up again once dry, and go thru the annular seasonal humidity cycles??? I questioned that if Super glue was used initially, would it prevent this "natural closing"??

The trick with that is to soak it in thinned white glue and then let it dry again, the splits do normally never open up again when treated that way.

 

[Dale Miner]

I've had the same occurance. A wild (black) cherry bowl about 16" diameter roughed, dried for at least a year, the outside roughed, and the inside left for the next day. A warm low pressure front moved in and the bowl was 9/16" out of round the next day. The bowl was brought back into the house for a few days. During that time the weather turned cool and dry and the bowl returned back to within 1/16" of being round. The inside was finished turned, bowl sanded, oil applied, and found a new home .

Wood is alive even when the tree it came from no longer is.

 

[Odie]

With your bowl, would the heat from returning it to round, and then sitting in your shop that (Guess here) temp and bowl cooled off overnight, and therefore with the humidity going up the bowl did get oval.

So as you found it oval and set it away, it then got time to dry and get warmer equally, with the outcome of going back to round, maybe far fetched, but I do wonder the affect of these forces that do occur like that, ?????????

Than the other ????, are you sure it did happen

You know, Leo.......I'm just not sure what caused this warp, and return to round. Your guess is reasonable, but who knows?

Yeah, I did question my sanity when I saw the bowl had returned to round!

ko

 

[Bill Boehme]

Odie, I don't know if you are a Trekkie, but maybe there was another kind of "warp" going on ... as in traveling back a few days in time before the bowl warped. Don't scoff. I'm sure that there's a paranormal cable TV channel that would pay big bucks for the story. If you have any Sasquatch pals, that would be icing on the cake.

 

[hockenbery]

I have had an idea that I've been meaning to try. I want to soak a square blank and then compress it in a hydraulic press and let it dry. Then round the blank and turn a bowl and finally put the bowl back in water and let it relax again. Has anyone ever tried this?

On a smaller scale
I have seen a pimpled surface created by compressing the wood into dimples with a round punch.
The surface is sanded smooth then hydrated popping the compressed wood up into a cool pimple covered surface.

 

[Emiliano Achaval]

Thank god somehow I ended up living in Hawaii. I'm into my 31 st year here. I could not live some where where its 30 degrees... I have never seen one bowl warp back to center... Heck, seems that you look at them and they warp, when I rough big Koa bowls, if I stop for lunch they already warped a little, wish they would always bounce back! Aloha

 

[Odie]

I could not live some where where its 30 degrees...

Thirty degrees? Sometimes it's a couple of months between times it gets that hot around here!

ko

 

[Emiliano Achaval]

Thirty degrees? Sometimes it's a couple of months between times it gets that hot around here!

ko

Haha! The good thing is our hobby is done indoors!! I would have central heating in my shop!!