Cupped table top, what to do

[Pabs]

Ah Elm is it thank you.

What about wetting or steaming the top and clamping flat, could that improve things?

if achieved (would need to dry clamped which would be for a long time after steam saturation) would this then lead to a high risk of secondary cracks / splits in the existing individual boards? - or could this actually work?

edit I am reading about boat building atm so am throwing words about with abandon - but an honest question it is.. and cask makers (coopers) using old mashmakers wood and the such, from a like of the light golden stuff! and mebe I rephrase a little too, oh the insight of the honey dew liquor!

 

[TimV]

Just a thought. If you're taking it apart and splitting it longitudinally, you could consider re-assembling so that the strips have the grain curvature in alternating directions. That way, although each strip will still curve with humidity/temperature, its neighbour will do so in the opposite direction, so you'll end up with ripples rather than a huge dish. But you may have too many screw holes on the underside to make this feasible.

 

[Sgian Dubh]

One possible cause of the cupping in that table is moisture cycling. If it's a table that's been used in, for example, a kitchen, maybe the top surface was scrubbed clean with water on a fairly regular basis. Each application of water to the top surface and the subsequent drying is a moisture cycle. The wood cells near the top surface of the wood adsorb a little water and swell, then dry and shrink again. The result is the cells near the upper surface gradually distort and collapse putting cross-grain stress on the panel leading to cupping powerful enough to break the connection between the underside of the top and the tables rails, or any other cross-grain reinforcements, e.g., slot screwed bearers.

All the above pure speculation because I have no knowledge of the table's previous purpose. I know it's relatively modern though because of the machine cut dovetails seen in one of the snaps. Machine cut dovetails suggests manufacture some time within the last 120 years or so, and unlikely to be made before about 1900 AD. Slainte.

 

[zak99]

if achieved (would need to dry clamped which would be for a long time after steam saturation) would this then lead to a high risk of secondary cracks / splits in the existing individual boards? - or could this actually work?

edit I am reading about boat building atm so am throwing words about with abandon - but an honest question it is.. and cask makers (coopers) using old mashmakers wood and the such, from a like of the light golden stuff! and mebe I rephrase a little too, oh the insight of the honey dew liquor!

Having worked on wooden boats I’ve done a fair bit of timber steaming. I’ve only ever seen it used to bend wood longitudinally ie across the grain and not so much with the grain as in cupping. Although a steamed twist is common as in planking. Also from my experience it’s usually done on new high moisture timber, eg fresh cut green oak boat frames are kept soaked before steaming and bending. It dries back to where it was before soaking pretty quickly and is incredibly strong. Old wood is of course well dried out, I was just thinking out loud at the start here as theres loads of stuff on t’intenet saying water to fix cupping but maybe that’s for new wood

 

[Yojevol]

I had this problem to deal with 4 years ago. I used the slot cutting and filling on the underside method. See my write-up here. It's in 2 parts.
Brian

 

[Jacob]

I had this problem to deal with 4 years ago. I used the slot cutting and filling on the underside method. See my write-up here. It's in 2 parts.
Brian

I did it with some wide window boards. I'd left them a long time in position without fixing and they curled up. Very wasteful, so I kerfed them with a hand held circular saw. Slots about 75mm apart and 20mm deep in 24mm timber. They screwed down brilliantly and just needed belt sanding on top and a false lipping applied to the front. Seem to be surviving well - I thought a slot or two might brake right through but they haven't.
On a table top perhaps do the same but plant breadboard ends to cover the slots and help keep it all flat.
I wouldn't bother filling the slots if they are out of sight - the top might bend again.

 

[Simon89]

I would leave it as it is.

it’s part of its character. It tells a story. It reminds you of it’s age.

 

[jcassidy]

I would just go for a new top and reuse the existing top as wall art or store it away for future resale.

Especially if I expect people to eat off it. Who knows what lovely chemicals have been spilt on it. You're going to destroy the patina on it anyway sanding it down to flat.

I wouldn't paint the base, a good clean and seal with wax.