Panels cupping while finish drying

[Juss1]

I made a several raised panels.  Used a planer sled to flatten them and finished on drum sander and sanded down to 240.  They weren't dead flat but I'd say the worst was no more than 1/32" off when checking on flat surface.  I applied Arm-R-Seal and let them dry outside.  It's a little warm for the season but not hot.  Like high 70's.  When I check on them later in the day they had all cupped.  Some a little some alot.  The worst was now close to 1/8" off.   Could this have been caused by the heat?  The panels were a warm when I picked them up.

[JGrout]

one side finished only?

the major cause of cupping right after improperly dried lumber

[jteneyck]

They are likely to flatten back out again on their own when the MC equilibrates.  Bring them back in and wait a day or two. 

It's best not to move wood from one place to another when building/finishing something. 

John

[Juss1]

Joe both sides were finished. I got the boards from 2 different lumber yards. Some were regular KD and the rest were from a recycled barn that were S2S

John I usually apply finish and let pieces dry in the garage but there were alot many pieces this time and figured it was faster and easier to do it outside.

[JGrout]

Some were regular KD and the rest were from a recycled barn that were S2S

  can you tell the difference? 

I suspect the barnwood was air dried and even old it would not act the same as the KD stock.

[joe1086]

Were any of them sitting exposed to direct sunlight?

[TomFromStLouis]

My guess is that the sun baked the top and if the cupping formed a shallow bowl then I could be right. As suggested give them a day or two indoors with air flow all around and it is likely the problem fixes itself.

[MichaelMouse]

Joe both sides were finished.  I got the boards from 2 different lumber yards.  Some were regular KD and the rest were from a recycled barn that were S2S

  can you tell the difference? 

I suspect the barnwood was air dried and even old it would not act the same as the KD stock.

I suspect that both, if they had been in the shop for a week or two, were at the same equilibrium.  Makes no difference if they were KD or AD originally.    Now they're BOTH air dry.

https://www.fpl.fs.fed.us/documnts/fplgt...3/ch03.pdf

[JGrout]

Well I disagree with your conclusion.

I have treated both differently for good reason, I have experienced similar conditions when mixing AD and KD.

[Juss1]

Yes.  They were in direct sunlight for several hours.  I can't work on them till this weekend so I'll try and let them be and hope it flattens out a bit.

Joe I don't remember exactly which ones were AD and which were KD.