Reposting this since photobucket blocked my pics.
We've gotten a lot of compliments on our boxing method when we ship, I thought I'd share it here. Similar to Scratch's method but with a few refinements.
The framed piece is first wrapped face down in microfoam wrap. We fold the ends under in opposing directions to create an extra padding on both corners. Label the top/front for orientation as you're wrapping it.
We measure the piece, add about 3/8" in both directions. Cut three pieces of corrugated cardboard to this size, one piece for the bottom, two for the top with the flutes of the corrugation running in opposite directions. Layering the opposing corrugation increases the durability to protect the face.
Cut two pieces of cardboard the length of the long side of your box and about 5" wide with the corrugation running the length. Crease the pieces and tape them into place. Repeat for the short sides slipping the first tab behind the print, then the front side in between the double layer of cardboard facing. By doing so you create a locked corner that can't collapse on itself. Tape the corners for a bit of extra reinforcement. Again, keep track of the front/top of your framed piece.
If we're using a private currier (someone who knows what they're handling) instead of UPS, this is the stopping point, we refer to it as an inner box. For UPS we continue on...
For the inset of the outer box, cut a piece of cardboard, allowing for 2" on both sides, as well as in front and back of the inner box. So an inner box size10"x20"x2" would require a piece of cardboard 26"x36" for it's outer box.
Mark 6' in on all sides.
Notch out the cardboard
against the corrugation (this is important later).
Using a straight edge, crease the cardboard along your marked lines. Creasing cardboard against the grain is no fun an will beat on your hands. We find using a thin poster tube sliced longways and slipped over a straight edge helps provide a grip.
Fold the tabs inwards and tape the corners.
Measure the inside of the box and cut a piece of cardboard with the flutes running the opposite direction to fit it into the bottom for additional reinforcement.
Repeat the same steps for the lid with a piece of cardboard 1" larger in both directions and the corrugation running the opposite direction as the inset box. Finish two sides measuring in 1/4" more than the inset box. Mark the two remaining sides to fit the bottom half and finish the top. Finish with another piece of cardboard (alternating flute direction, always alternating...) to fit snugly in the lid as you di with the inset box.
If you've alternated your corrugation, when the lid is snugged onto the inset box the folded corners are on both sides of the corner, the flutes running the width of the box providing crush protection and making for a very sturdy corner.
Three layers of 1" bubble wrap in the bottom of the box.
Center in the inner box.
We then use rolls the small 1/4" bubble wrap to fit the channel around the inner box.
Top off with more layers of 1" bubble wrap on top. Don't forget to check your orientation of front/top before you close the box.
Snug the lid on, tape it shut, first strap tape across from front to back, then lengthwise along the seams.
Affix "Fragile" stickers to all sides. We always align the stickers tags to reflect the orientation of the print inside the box, both front and back. As well additional "this side up" stickers help keep your art facing the right direction while in transit (hopefully).
Off to the shipper, insure appropriately.
We've never had a problem with this method. I'm a strong believer in the alternating corrugation to increase the strength of the corners and faces of the box. It's much more difficult for a box to develop a crease or bend with this method. We obviously have a lot of tools on hand that make this easier to do for us, it still takes a solid 30-45 minutes if I'm moving quick on an average sized box. We have a lot of cardboard and bubble wrap to recycle from incoming supplies which is helpful, but we still have to buy larger sheets of cardboard for most boxes.
I much prefer bubble wrap to packing peanuts. It stays where you put it, it isn't a complete mess to deal with, and most peanuts are not environmentally friendly.
Foamcore will crease unpredictably in any direction under stress as well as it punctures easily, I would not recommend it ever as a packing material.
I hope you find this info helpful.