Ah Sean, the old timber grading and terminology beast awakes from it's slumber once again.
Despite the number of times this has been discussed here, I still can't pretend to understand all the different terms. I think mostly because i have yet to go to 2 consecutive merchants who use the same vocabulary. Some talk in "firsts" firsts and seconds" "fifths" (nothing inbetween?), "sorted" and "unsorted" etc. - it's all dutch to me. Just when I think I've got a handle on it I'll ring another supplier for a competitive quote to hear them babble on about "standard", "contract grade" and "best joinery".
If, God forbid, you have the temerity to request timber that isn't pretending to be holding up the Clifton suspension bridge sometimes they'll let you pick your own and others won't.
Mostly I rely on the seller being decent enough to advise me based on intended usage and let me have a hand in choosing the boards. If they won't generally I'll vote with my feet and go to someone who will, even if it costs me a bit more.
:shock: Blimey, sorry about the rant - must have touched a nerve there :roll:
As to your actual question; for skirting, especially if it's going to be painted, I don't think you need to go mad with the quality just go for cheap. If you buy Ex 25mm (1") PAR timber (i.e. "Planed All Round" sometimes called PAS - "Planed All Square" from 1" sawn) the finished size will almost certainly be about 21 - 22mm. If you buy sawn and thickness youself 25mm will be adequate for you purpose. After all the back will never be seen and only needs enough removed to be flat enough for a referance surface when you plane the face.
as to being straight, again don't get too obsessed. It only needs to be straight enough to go through the shaper for the profile. You are then going to nail it to a wall (which is almost certainly not dead straght) over a floor (..er ditto)
thanks all.
