Reducing warp?

[Spotswood]

Almost everywhere you read that in order to reduce warping after thickness planning you should plane both sides equally. Well, that hasn't worked out so well for me. (And yes, I always sticker and clamp the boards overnight.)

Since wood tends to shrink more on the sap side, wouldn't it be better to just plane that side of a board?

[China]

Did you check the moisture content of your timber, timder that is not well seasoned will move all over place

[IanW]

Rich - all rules have exceptions. In general, it's a good idea to take equal amounts off both sides, & as long as the MC has the same gradient from each side, you should be ok. But there are situations where you might want to remove more off one side or the other - a bad blemish, for example. Whether or not things move, depends on quite a few factors, not the least being how even the MC is, & how symmetrical the growth rings are & if quartered or flatsawn. So it's not solely a quaetion of uneven or excessive MC. The presence of sapwood, particularly if it's reactive sapwood (i.e. from a bend or crook) is always a potential bother. Most sapwood spells trouble of one sort or another (borers, colour difference, uneven taking-up of stains & finishes) but any reaction wood puts the board under tension on that side. So it definitely needs to come right off, & even then, the older wood is likely to be lively.

And some woods just fall into the 'mongrel' class - you can do everything right, & they still go all over the place. The best thing to do with that sort of stuff is avoid it, as it will never behave. A good example is Celtis - ok for making handles, (maybe - there are better woods) but not recommended for furniture!

Cheers,

[Manuka Jock]

Rich , what do you mean by 'warp' ?
Cuped , out of wind , bowed , twisting ??

[Rattrap]

I like to use Blackheart Sassafras but it defenately sits in the mongrel class. Even kiln dried it'll move & move & just when u think its finally stabilized it'll move again. Most often this is seen when i first machine up a from rough sawn, the next day it'll have a bit of a twist or cup - not heaps but enough to get under my skin. So now i machine down to within a couple of mm then leave the board for a few days then machine to final thickness. I usually don't get enough movement to be a problem from there.

[Claw Hama]

Yep, a bit like a good wine, needs to breath a little once open. As RT said take it almost down to the size you want then let it stand over night or longer if you have time, let it do what it wants then just dress it lightly. Even a hundred year old timber will still move if and when it wants.