Please share where any materials can be purchased?
I use Clear Bags. They are lightweight, archival, clear plastic bags that the art goes in. You can get them in just about any size. I get them from www.clearbags.com. (after that I wrap the whole thing - including a packaging slip and business card - in craft paper, and put it in a usps priority mail box, padded with crumpled newspaper)
Are the 6 1/4" x 6 1/4" bags wide enough to fit a 6x6 gessobord or do you buy a bigger size for a roomier fit?
I sell mostly small pieces and send them in a padded Priority Mail envelope. I start by wrapping the painting in a clear wax paper to protect the painting itself. Then the painting gets sandwiched between two cardboard pieces with spacers between them. I put the spacers in to keep the cardboard pieces from pressing down too hard on the painting. The spacers are also placed to keep the painting from sliding around in the package. I ordered the cardboard pieces from a company on Ebay and paid about $15 for 100 pieces. The size is perfect for the padded envelope, taking up all the room inside. I can send anything up to an 8x10" painting in this setup.
I was grateful for Karen Margulis’ blog and her ideas for posting (shipping) pastel paintings. So far I’ve sent several small pastels from England to America and they’ve all arrived safely. I use glassine paper to protect the pastel surface (for those of us in England, Jacksons Art in London sells this). I had difficulty finding suitable foamboard locally, so decided to cut up some hardboard and make two rigid panels to sandwich the pastel between (with a small overlap all round). These are then firmly taped so that they don’t move. My local post office sells a good supply of lightly padded mailing-bags, and in various sizes, so that (so far) I’ve had no difficulty mailing off a 9x9 inch panel sandwich. Admittedly hardboard panels are a bit heavier than foamboard, but they seem to travel overseas just fine.