For packing a painting Rolled in Tube for shipping the most important things you need is - archival tissue paper and a sturdy cardboard tube. Note that any material that comes into contact with the surface of the work should be acid free or archival quality.
Make sure the paint needs to be utterly and totally dry, not just touch dry on the surface. Wrap the painting in archival tissue paper. Also always remember to write your name or shop name with date (when the painting was created) behind the canvas before start rolling.
Lay the canvas down flat on the acid-free paper with the painted side down. all layers are absolutely flat with no wrinkles.
Roll the paper and the canvas up together, that you're rolling up the canvas with the painted surface on the outside, and it should covered with the paper.
Make sure you roll it loosely. You can use some colorful thread to tie up the roll to give a nice look to your packing.
If you want you can add COA and a thank you letter with a note to your buyers that - The painting can then be re-stretched onto new stretcher bars in an art or framing shop near your home.
Now Slide the rolled-up canvas into the cardboard tube and enclose it with fitted plastic lids. All set to ship the painting.
I have a little photo tour for you throughout the process of packing. Take a look here -