Another question about wood movement t

[Randy C]

If you have a panel built out of 2 by 6 by 22 “ long red oak boards that  you assemble side by side in order to have a panel that is 8ft long when finished, do you still have to worry about wood movement if you completely seal every exterior surface of the wood panel with something like poly. Would the wood still expand across the grain or would the sealing with poly stop wood movement and expansion?

Thanks

[fredhargis]

Yes, it will still move. Think of all the table tops that are finished all over and they still plan for movememnt when doing things like breadboard ends and fastening the top to the frame.

[jteneyck]

To add to what Fred said, finish protects the wood from liquid water but does not stop the transfer of water vapor i.e. moisture.  So as the seasonally humidity changes, so will the moisture content of the wood, meaning it will expand and contract in response.  

You can control the overall length of your panel, and maintain exactly 8 ft, if you install the boards separately with a gap between them.  If you've ever heard of "nickel gap", that's what it's about.  1/16 - 3/32" gap between 6" wide boards should do it.    

John

[Ridgeway]

To add to what Fred said, finish protects the wood from liquid water but does not stop the transfer of water vapor i.e. moisture.  So as the seasonally humidity changes, so will the moisture content of the wood, meaning it will expand and contract in response.  

You can control the overall length of your panel, and maintain exactly 8 ft, if you install the boards separately with a gap between them.  If you've ever heard of "nickel gap", that's what it's about.  1/16 - 3/32" gap between 6" wide boards should do it.    

John

Won't that look like you are eating dinner on top of a railroad track though?  OTOH, if you glue up those 16 or so pieces, it is really gonna want to warp, in addition to growing a couple of inches every summer.

Not being snarky, but I'm thinking there is a reason people orient long boards lengthwise when making a table top.

[jteneyck]

Won't that look like you are eating dinner on top of a railroad track though?  OTOH, if you glue up those 16 or so pieces, it is really gonna want to warp, in addition to growing a couple of inches every summer.

Not being snarky, but I'm thinking there is a reason people orient long boards lengthwise when making a table top.

You didn't say you were building a table.  

I didn't say to glue the boards together.  Gap or no gap would make no difference if you glued the boards together.  

It doesn't matter which way you orient the boards when making a table - as long as you make provision for wood movement.  There are time tested ways to do that.  Get a good book on furniture design/construction.  

John

[CStan]

Finish won't stop movement and you've picked one of the worst species you could in terms of movement.