Here’s a better version of the painting I used for my banner. It was a private commission and is the largest watercolour I have ever painted – 38×28 inches (96x71cm). The biggest problem was in stretching the paper; the only paper I had this size was Arches 90lb in a roll and I knew it would buckle horrendously without stretching. So I wet the paper, taped it to a board and allowed it to dry naturally. But I underestimated the forces involved when the paper shrunk; I knew there was a possibility the paper could rip, but in this case it just pulled away from the gummed tape. I ended up using PVA glue around the edges, together with more tape and staples (from a staple gun). Thankfully it worked!
Click pic for a bigger version