Is this fixable? How?

[Alan Lightstone]

I built a cover to place over the glass rocks on my outdoor fire pit table. It's made out of cypress, with a steam bent vertical piece bent in a circle, covered by a flat cypress circle.

The cover was finished with General Finishes EXTERIOR 450 outdoor varnish, sprayed on. The cover came out looking fantastic.

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The problem is what has happened to it over the past month. The cover has warped impressively. At first I thought it was just the steam bend supports, but it's actually the top that has turned into a pizza. It is sitting outside in the Florida sun and rain. I thought cypress would be a good choice for outside, but the amount of warpage is impressive.

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Is there any way to fix this? If it hadn't been finished, I thought of building a big steam box and steaming it, then fastening flat angle iron underneath it to avoid it rewarping.

[Richard Coers]

How thick is that steam bent ring? If it is glued, or screwed through small holes, it is probably restraining the movement of the lid. One side is restrained, over side it free, wood movement makes a potato chip.

[Jeff Duncan]

I doubt you'll be able to fix it once it's gone. Fastening metal to wood to try and prevent movement usually results in the wood failing. You cannot really stop wood from moving, so by trying to "force" the wood into submission you'll simply end up with other problems.

I don't know of any way to keep something like that intact when it's in full exposure....maybe someone else will have better advice:o

good luck,
JeffD

[Gordon Eyre]

It sure was pretty when you started.

[Doug Richardson]

It was OK, until you screwed that knob on.....lol!

[Alan Lightstone]

Yup. Clearly the knob. LOL.

The steam bent ring is 1/2" thick. Not much fun to bend, either.

Sob...

[Jason Beam]

Did you apply the same amount of finish to both large surfaces? That's a big one - treat both the same.

Is the wood mostly QS? That's another - QS lumber is MUCH MUCH more stable

I doubt the ring is holding back expansion/contraction as it should flex enough along it's diameter to be mostly okay, but it's not a bad thought to keep in mind. Not sure how you'd attach it otherwise and still have it look flush as much as possible. It doesn't ring out as a glaring problem if the above two factors are missing. They're my first suspects.

And yeah - you *might* be able to flip it over and let the underside dry out (if it has no finish) and it *might* flatten to some degree but I doubt it'll ever go back to the nice flat surface you had at the start.

[Lee Schierer]

It is warping because the top can't move. You need to attach the ring in such a way that the top can move. The top will expand and contract across the grain. Can you attach the top only at the edge near the middle of the grain where the end grain meets the edge?

[glenn bradley]

That really was a beautiful cover Alan. If the top is warping due to being restrained, I would attach the top of your replacement build the way one does a table to allow movement. If, however the potato chip effect is the top warping and the ring is just following, this will not help.

I agree that trying to force wood to stay still is an exercise in futility and always ends badly. If cypress is a Florida-compatible outdoor wood, a floating top should cure your ills. We use cedar and redwood for outdoor stuff in SoCal and NOT finishing it is the rule. If you put on some Thompsons or some type of oil, you will just have to do it again in a couple years. If you let the material season naturally, it is maintenance-free till it dies of old age.

There are white oak benches in the botanical gardens at the University where I work that have sat untreated in the elements for a decade and more. They turn that beautiful silvery grey that such things do.

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[Alan Lightstone]

Top and bottom both finished. Equal number of coats.

You know, I never thought of treating it like a table to allow movement. Should have, obviously. Would not have been difficult. The difficult part of the job was the steam bent rings.

It's not QS. The rings are, for typical steam bending reasons. The top is plain sawn.

If I can detach the ring (won't be pretty - glued, and I presume I did it securely), how could I flatten the top? Way too potato chip to joint/plane without it becoming too thin.

I chose cypress as being a very outdoor friendly / tolerant wood. Could have chosen cedar. Thought about it. Not fond of the silvery grey look, which I why I chose the finishing route.

[Mark Bolton]

Ill bet the grain is running right up the dip in the chip. Once the ring is off you may be able to either flatten it with battens on the back or rip it in half right in the valley of the dip and glue it back together and flatten. It's definitely an issue of constraining the movement with the ring. Same thing would happen if you picture framed a solid wood panel.

[Sam Murdoch]

Maybe once you have removed the ring add a few banana board braces that will then be hidden by the ring. Don't know how much clearance you have under but the more thick the banana boards the more effective. They might each have a different shape to overcome the warp. Maybe crossing in the middle is useful but I think 2 set parallel will be better as will allow for the full thickness. These too will need to be secured in such a way to allow the top to move independently from them.

[John TenEyck]

I'm pretty sure you will be further ahead to chalk this one up to learning, and make a new one allowing for the top to move. The first one sure was beautiful, and I'm sure the second one will be just as nice.

"Know when to hold 'em, know when to fold em'."

John

[Mel Fulks]

Hard to make something flat hold up outside with a furniture quality finish . I would leave it twisted,add wood to bottom edge to get it flat, glue cotton duck ( or any kind of cloth) to all surfaces ,paint with acrylic exterior floor paint. Use bright color. An old technique that is quite durable. Its fine to lap pieces where needed. It will be a different thing ,but pretty.

[Mel Fulks]

I think if you did succeed in flattening ,it would just dip again. There is a rule prohibiting double dipping chips !

[Tai Fu]

I would have used some kind of a wood protector for outside patios, rather than furniture quality finish. They are never meant to stay good looking outside for more than a few days, especially considering what the sun does to finishes.

[Peter Aeschliman]

Here's another hypothesis- the lid looks like it sits "sealed" to the table top. Could the problem be that the outside is exposed to moving air, and the underside is not? Perhaps the air trapped between the lid and the table top is more humid, or maybe the humidity is more constant. The direction of the cupping indicates that the outside surface is dryer than the underside (the outer surface shrunk, thus pulling the edges up).

My dad has a nice thick bamboo cutting board. He used to wash it after use, and leave it on his granite countertop to dry. Problem was there wasn't free air movement on the underside, so the top dried faster than the bottom. Over a few months, the thing was really badly cupped, in the same direction that your lid is cupped. I milled my dad's cutting board flat again, and from now own, he lets it air dry on a cookie drying rack. It has stayed flat for years.

So perhaps it would help to put some feet on your next version to allow free air movement underneath? Just a thought.

[Howard Acheson]

You are a victim of wood movement and restricting the ability of the item to move.

I am assuming that the top is made from solid wood. If so, the wood top is going to expand and contract across the direction of the grain with changes in the wood moisture content. The outside rim is going to try to stop the movement across the grain. This causes warping and possible damage to the wood and glue joints.

Second, putting the top on when there is still residual heat from an extinguished fire will cause unequal moisture content on the outside of the top and the inside surface of the top. Again, this will cause warpage. This second situation is going to be more problematic that the first situation. The first can be remedied by rebuilding the circular top using exterior plywood. But this solution may not be effective with the second situation.

[Mark Bolton]

Hard to make something flat hold up outside with a furniture quality finish . I would leave it twisted,add wood to bottom edge to get it flat, glue cotton duck ( or any kind of cloth) to all surfaces ,paint with acrylic exterior floor paint. Use bright color. An old technique that is quite durable. Its fine to lap pieces where needed. It will be a different thing ,but pretty.

now that I got.. Chuckling

[Mark Bolton]

I would have used some kind of a wood protector for outside patios, rather than furniture quality finish. They are never meant to stay good looking outside for more than a few days, especially considering what the sun does to finishes.

He used a good exterior finish.. It has nothing to with the finish.. It was in the manufacture (which he now understands).. The finish is irrelevant. No amount of finish would have saved this piece.

[Alan Lightstone]

I think if you did succeed in flattening ,it would just dip again. There is a rule prohibiting double dipping chips !
LOL.
I used a waterproof, exterior, UV protectant finish, but couldn't help myself making the furniture quality finish. SWMBO was very particular about how it must look.

[Alan Lightstone]

No amount of finish would have saved this piece.
Perhaps 1000lbs of finish on the top, but the cost seemed excessive at the time.

[Alan Lightstone]

You are a victim of wood movement and restricting the ability of the item to move.

I am assuming that the top is made from solid wood. If so, the wood top is going to expand and contract across the direction of the grain with changes in the wood moisture content. The outside rim is going to try to stop the movement across the grain. This causes warping and possible damage to the wood and glue joints.

Second, putting the top on when there is still residual heat from an extinguished fire will cause unequal moisture content on the outside of the top and the inside surface of the top. Again, this will cause warpage. This second situation is going to be more problematic that the first situation. The first can be remedied by rebuilding the circular top using exterior plywood. But this solution may not be effective with the second situation.

Interesting. We haven't put the top on with the residual heat from an extinguished fire yet (It's a million degrees outside here, no need to light a fire pit). But I could see that could be a big problem when we start using it again. No way I'm going to go through the steam bending again to redo the ring. That I could fix with a wide belt sander. The top, however beautiful it once was, is now a potato chip. Is it possible to build a steam box, steam it, and bend it back flat? I'm assuming I would have to remove the finish first, but I would think, at least in theory it should work. I would then attach it only at a central point to the rings in a breadboard fashion, which should allow for seasonal movement.

[Tai Fu]

No if you steam it flat, it will potato chip again sometime in the future. Even with a good exterior finish the wood is still going to potato chip if you leave it in the condition you describe... the baking heat will dry the wood out and the other side will be wet, hence the potato chipping.

[Michael Wildt]

Sorry to see your hard work get messed up. +1 on all the good comments on how to save it. One thing that I see in the 2nd picture is that the finish appears to have gotten damaged by water. Looks like its bobbling, if so then water got in there and contributed to the warping. I bet the sprayed on finish was too thin to protect it.

[Mark Bolton]

No if you steam it flat, it will potato chip again sometime in the future. Even with a good exterior finish the wood is still going to potato chip if you leave it in the condition you describe... the baking heat will dry the wood out and the other side will be wet, hence the potato chipping.

Just for clarity the heat/cool, dry/wet, sides are not what the problem is. The steam bent ring constrained the expansion of the solid disk in the center. Even if this lid were in doors with equal air flow, heat, and light, on all sides it would have curled the instant the MC of the disk increased. It would have done it stored in the back of a closet leaning against the wall. With a rise in humidity the disk expanded. The steam bent ring tried its best to hold back that expansion. Likewise if the MC had dropped, it would have split the disk up the center because the ring is glued to the disk.

The cupping has nothing to do with heat/moisture or lack there of on one face vs. the other. Its an effect of the rings constraint alone.

[Prashun Patel]

Exterior grade woods like cypress are less prone to decay than interior grade woods. But all woods are subject to movement.

I also believe unequal airflow is a culprit here. If you nmake a new disc, id just put elevating feet on it instead of the ring.

[Jamie Buxton]

So as others have said, it is going to be pretty challenging to make that particular design work. A fix would be to go to a new design. Here's one. It is kinda like a hatch cover, but it is hexagonal. (An alternative design would be octagonal.) Water drips through the holes in the cover, so it doesn't get persistent puddles. (That's why the decks outside a house are built with gaps between the boards.) Air can circulate through the holes, which helps keep the top and the bottom of the cover at similar moisture levels.
It is all solid lumber. All the sticks in the hatch cover go from edge to edge of the cover. The joinery is just simple lap joints.

[Richard Wolf]

What a shame Alan, it was beautiful. Not an answer for your problem but, after a life time of trying to build things out of wood for outdoor use, I've given up. Wood and weather do not mix. I would make one out of metal and get it powder coated. It might add a new dimension to your hobby.

[John Piwaron]

Not only what the others have said. Restrained movement, unequal airflow, equal finishing on each side.

I'd give your design another shot. Using the advise given here. Allow for the disk to move. some sort of dovetail key arrangement, Z clips - something.

I'd also reconsider the choice of wood. It's not just about cypress being an outdoors wood, it's also about tangential and radial shrinkage. I'd be looking for a wood that shrinks pretty much the same in both directions. Mesquite is one of those. It tends to not warp. It's good outside. I have a piece made of mesquite outdoors right now.

Then there's the finish. In one of the pictures it appears that the finish may already be peeling or chipping. I really don't know a thing about that General Finishes product except that it's a waterborne product. So I'll say this: any film finish used outdoors is going to have to be flexible to have any chance of lasting. I've used a lot of finishes that made the claim to be "spar varnishes", UV protected, blah, blah, blah. All failed. And failed quickly at that. 'Cause basically they were polyurethane at heart. Poly's great in the right place. Outdoors isn't one of them. Polyurethane is hard and hard means brittle. It's going to crack. I've begun using a clear varnish made by Epifanes. It's something from the boat building world. I've got it on the trim and casing surrounding one window on my house. I've also got it on a pair of cedar benches outside. It looks good and it's holding up pretty well. Will it last forever and ever? Probably not, but if I have to so some minor touch-up now and then I won't be too unhappy. Even latex paint doesn't last forever. This Epifanes stuff isn't a polyurethane. It's a tung oil with phenolic resin. Applying it is like brushing honey. It's pretty thick. And it's flexible when dry.

I'd also give thought to using CPES. That's an epoxy sealer. It's pretty thin, meaning it's designed to penetrate the wood fibers to seal against moisture. It also acts as a primer to promote adhesion of the varnish. I get CPES from www.jamestowndistributors.com Disclaimer: I'm not in the employ of either Epifanes or Jamestown Distributors. But I *am* a satisfied customer.

Another choice for a finish might be to use West System epoxy. They have a special clear hardener when someone chooses to use their epoxy as a finish. That stuff may do a good job of completely sealing water out. The caveat is that you must use some kind of UV protectant over it. Like Epifanes.

[Andrew Hughes]

I agree with Mr. Wolf on this one make a new one out of metal and add a wooden knob on top.

[Alan Lightstone]

Not only what the others have said. Restrained movement, unequal airflow, equal finishing on each side.

I'd give your design another shot. Using the advise given here. Allow for the disk to move. some sort of dovetail key arrangement, Z clips - something.

I'd also reconsider the choice of wood. It's not just about cypress being an outdoors wood, it's also about tangential and radial shrinkage. I'd be looking for a wood that shrinks pretty much the same in both directions. Mesquite is one of those. It tends to not warp. It's good outside. I have a piece made of mesquite outdoors right now.

Then there's the finish. In one of the pictures it appears that the finish may already be peeling or chipping. I really don't know a thing about that General Finishes product except that it's a waterborne product. So I'll say this: any film finish used outdoors is going to have to be flexible to have any chance of lasting. I've used a lot of finishes that made the claim to be "spar varnishes", UV protected, blah, blah, blah. All failed. And failed quickly at that. 'Cause basically they were polyurethane at heart. Poly's great in the right place. Outdoors isn't one of them. Polyurethane is hard and hard means brittle. It's going to crack. I've begun using a clear varnish made by Epifanes. It's something from the boat building world. I've got it on the trim and casing surrounding one window on my house. I've also got it on a pair of cedar benches outside. It looks good and it's holding up pretty well. Will it last forever and ever? Probably not, but if I have to so some minor touch-up now and then I won't be too unhappy. Even latex paint doesn't last forever. This Epifanes stuff isn't a polyurethane. It's a tung oil with phenolic resin. Applying it is like brushing honey. It's pretty thick. And it's flexible when dry.

I'd also give thought to using CPES. That's an epoxy sealer. It's pretty thin, meaning it's designed to penetrate the wood fibers to seal against moisture. It also acts as a primer to promote adhesion of the varnish. I get CPES from www.jamestowndistributors.com (http://www.jamestowndistributors.com) Disclaimer: I'm not in the employ of either Epifanes or Jamestown Distributors. But I *am* a satisfied customer.

Another choice for a finish might be to use West System epoxy. They have a special clear hardener when someone chooses to use their epoxy as a finish. That stuff may do a good job of completely sealing water out. The caveat is that you must use some kind of UV protectant over it. Like Epifanes.

Interesting thoughts, all.

John, I actually have both CPES and Epifanes at home right now. I could try that approach.

No local sources for Mesquite here. Even the cypress took work to find. I could easily find oak, and a variety of other hardwoods. I have some excess cherry and sapele just sitting around. Some more exotic woods too, but planning to use them for other projects.

The picture is just showing some water stains from the hard water down here and the sprinkler system. I can assure everyone that the finish appears intact. I can 't find any areas that have seemed to have water intrusion. Certainly no bubbling.

I think this is entirely wood movement with over vigorous restraint of that by the ring.

[Jim Matthews]

What if there was a second ring, with an ID the size of the current OD?

Make the second ring as the first, only leave it free of any top or fixture to the frame around the fire pit.
When you're ready to cover things, center the ring and drop in the existing top.

[Rich Engelhardt]

A disk shape, regardless of the material it's made of, needs some sort of inner ribs to stabilize and strengthen it.

Go to Google and select Images - then search for - underside of manhole cover

That's how you'll need to make it. I'm not sure of it's possible to salvage the one you have or not.

[John Piwaron]

Interesting thoughts, all.

John, I actually have both CPES and Epifanes at home right now. I could try that approach.

No local sources for Mesquite here. Even the cypress took work to find. I could easily find oak, and a variety of other hardwoods. I have some excess cherry and sapele just sitting around. Some more exotic woods too, but planning to use them for other projects.

The picture is just showing some water stains from the hard water down here and the sprinkler system. I can assure everyone that the finish appears intact. I can 't find any areas that have seemed to have water intrusion. Certainly no bubbling.

I think this is entirely wood movement with over vigorous restraint of that by the ring.

It's possible to mail order mesquite. I did that to get the boards I used. Mine came from Texas Kiln Products long ago. There's another place - http://www.mesquitedesign.com/lumber.htm

The only issue I have with ordering lumber is the cost of shipping.

[Curt Harms]

So as others have said, it is going to be pretty challenging to make that particular design work. A fix would be to go to a new design. Here's one. It is kinda like a hatch cover, but it is hexagonal. (An alternative design would be octagonal.) Water drips through the holes in the cover, so it doesn't get persistent puddles. (That's why the decks outside a house are built with gaps between the boards.) Air can circulate through the holes, which helps keep the top and the bottom of the cover at similar moisture levels.
It is all solid lumber. All the sticks in the hatch cover go from edge to edge of the cover. The joinery is just simple lap joints.

I was thinking of the hexagonal or octagonal as well. Make the vertical edge mitered segments but don't butt 'em tight, leave a little gap between each one so they can come & go as the top moves. Cut a rabbet in each end of each segment so they overlap but are not fastened to one another, that way no daylight shows through? Maybe cut shallow arches into the bottom of each segment so there's some air flow to the underside of the top?

[Alan Lightstone]

What if there was a second ring, with an ID the size of the current OD?

Make the second ring as the first, only leave it free of any top or fixture to the frame around the fire pit.
When you're ready to cover things, center the ring and drop in the existing top.
Having trouble wrapping my head around this one, but the thought of a top not attached to a ring (keep the parts separate) is interesting, and should work.

The part of the job I'm trying to avoid is the steam bending of the ring. That really was difficult and wasn't particularly fun. Just making a nice top, as you all know, is fairly basic work.

[Alan Lightstone]

I was thinking of the hexagonal or octagonal as well. Make the vertical edge mitered segments but don't butt 'em tight, leave a little gap between each one so they can come & go as the top moves. Cut a rabbet in each end of each segment so they overlap but are not fastened to one another, that way no daylight shows through? Maybe cut shallow arches into the bottom of each segment so there's some air flow to the underside of the top?
Other multi-sided geometric shapes for the support ("ring") is intriguing. While it won't necessary provide the look that the LOML was looking for, it will potentially still be very good looking, as well as serve the function of protecting the fire glass from being hit by golf balls and spraying all over (the table is on a golf course, with lots of questionably talented golfers.)

Now if I made, say, a hexagon or octagon support ring, there should be minimal lengthwise movement on each segment, but most of the movement will be width-wise, correct? Will it be consistent (the whole top raise up and down) if it stays unattached to the top, or only attached on one point on each side)?

Alternatively, if I use Curt's suggestion above, is it enough that the individual segments aren't attached to each other?

[Alan Lightstone]

A disk shape, regardless of the material it's made of, needs some sort of inner ribs to stabilize and strengthen it.

Go to Google and select Images - then search for - underside of manhole cover

That's how you'll need to make it. I'm not sure of it's possible to salvage the one you have or not.
OK, the strangest and neatest Google search I'll make today. My biggest question, Rich, is how did you know what the underside of manhole covers look like????

Unfortunately, because of the fire glass underneath the center of the top, I can't have anything supporting the top circle except on the outside. It has to be a minimum of 24" in diameter, and 1.25" high at a minimum. I'll try to take a picture of the fireglass underneath later, but it keeps raining down here.

[David C. Roseman]

As a reformed former sailboat owner, I've spent years lovingly fussing with exterior wooden trim in a harsh (marine) environment. I can appreciate all the advice given here about wood, water and sun being a tough combination. :eek: But if you're set on having a wooden cover with a clear finish, and willing to spring for the materials, it can certainly be done. There are many companionway hatch covers made with marine-grade teak plywood, trimmed with 4/4 solid teak sides rabbeted to the top. I'd definitely not try to go round, but rather hexagonal or octagonal, as you're now considering. Use one of the exterior marine wood finishes marketed for sailing applications. It will be beautiful, but be prepared to repair or recoat the finish every year. You may eventually decide that a semi-gloss exterior enamel in the color of your choice looks pretty good, after all. :)

David

[Tom Hammond]

Remove the ring and flip the top and leave it for a while. It'll come back, or mostly. Then find an alternative solution to reattaching the ring that allows the top to expand and contract along the length of the grain. Have made similar mistakes in the past... usually not a disaster if you get on it soon.

[Peter Aeschliman]

The cupping has nothing to do with heat/moisture or lack there of on one face vs. the other. Its an effect of the rings constraint alone.

Yes, the ring hurt the situation, but the severity of the result has to do with both unequal exposure and how the top was fastened down. This is why we sticker green lumber to let it dry- all sides need equal exposure so that moisture can be absorbed and expelled at the same rate on all surfaces. Otherwise, you end up with unusable lumber (cupped, crooked, bowed, twisted).

Take a hypothetical situation- if he hadn't attached the top to a ring, and simply let it sit flat on the granite table surface pictured, left it out in the rain and then the heat, it would still have warped like mad. This is because of unequal exposure- the top would take in tons of moisture and then expel it very quickly when the sun came out, while the underside of the top would not be exposed to such wild moisture swings.

As I said in my last post, this is the same phenomenon that caused my dad's cutting board to cup like 2" across its width. After flattening it, he used the cutting board exactly the same way as before, except he lets it air dry on a cookie drying rack, which lets air flow on all sides. It's still as flat as the day I fixed it for him.

Even if the top was attached with sliding dovetails, it would still have been powerful enough to warp the ring. The top side of the workpiece shrunk more than the underside because the top literally had water sitting on it, while the underside was dry all along. And it was exacerbated by the fact that the underside was fastened rigidly to the ring.

In other words, both phenomenon- the fastening method, and the air exposure- would have caused the problem on a standalone basis. Combined, you get extreme results like we see here.

[Alan Lightstone]

Thanks, Peter. You're explanation makes great sense.

No sense screwing up a little. Might as well have the piece go out in a blaze of mistakes.

[Jim Matthews]

Now don't pout.

You've got this, and we believe in you.
Now go make us proud.

[Steve Kohn]

Why couldn't you make both the ring and the cover hexagonal or octagonal? Then they would move more equally with each other.

[Rich Engelhardt]

My biggest question, Rich, is how did you know what the underside of manhole covers look like????
LOL! Yeah - not what you'd call your everyday type of thing!
35 some years ago, when I worked in a paint store in Lorain Ohio, we called on the city of Sandusky Ohio as a customer. I was tagging along on a sales call one day when we called on either the water or streets department. I asked why manhole covers were round and got a lot more of an answer than I really wanted :D.
It's one of those "small talk" type of things were you ask a question, just more for the sake of conversation. I only remember it because of the irony attached to it.
The guy we were talking to was killed a few months later in a freak accident when a gasoline truck overturned and spilled it's load into the sewers. He was in the process of lifting a manhole cover when the gas blew.

[Mark Bolton]

Yes, the ring hurt the situation, but the severity of the result has to do with both unequal exposure and how the top was fastened down. This is why we sticker green lumber to let it dry- all sides need equal exposure so that moisture can be absorbed and expelled at the same rate on all surfaces. Otherwise, you end up with unusable lumber (cupped, crooked, bowed, twisted).[/QUOTE
I agree fully that moisture on both the top and the bottom of this piece are a problem however I would venture to guess they only seriously came into play after the cupping had begun to wreak its havoc. The cap looked to have been finished nicely with a good product and as he stated had equal coats on all sides. All the damage/degrade you see is likely from large amounts of moisture infiltration after the disk had started tearing the lid apart, separating the wood fibers, breaking the finish, and self destructing. At that point the water began to infiltrate and things got worse.

While the airflow under the lid is likely not equal to the top, the lid is not sitting flat on a granite surface like a cutting board. There is a void under there and likely a very dry void at that because its a fire pit. Its a given that over time the piece may still likely have cupped without some cross grain battens or some other means to resist the cup but the extent to which it happened here is, in my opinion, solely due the constraint of the ring. We have all had issues with cutting boards washed, left wet, and laid on a counter. Different animal but yes the principal applies.

If you punch the width of that disc into the shrinkulator, get the result, and then ask yourself how that movement was to be accommodated? Or try it for the heck of it in your own shop. Cage a wide single board, and leave wide board just as is right next to it. Sun or shade, damp or dry, it will fail. The lid as made is for all intents and purposes a cross-grain situation.

[Mark Bolton]

Yes, the ring hurt the situation,

Some how I guess I clipped part of my post when I posted,..

I agree that the water/moisture is an issue however I would venture to guess the majority of that water damage/moisture infiltration happened after the disk had already begun do destroy the lid. As the disk expanded and destroyed the finish, separated wood fibers, and so on, more and more water got in worsening the situation hence all the checks/cracking. If you imagine that disk expanding even slightly, the ring would be under tremendous tension, far more than any finish would withstand. The instant that happened the moisture issue is exponentially worse but it isnt what caused the problem.

I agree there are several factors here, but as has been mentioned, there are real world instances where things like this are built and survive regularly. The boat hatch is a perfect example. You have a shady, confined, damp, below-deck area, and a sun baked outer face. But trap the grain, and your dead.

At any rate its a good lesson learned.