I've posted in the past about large and oversize mounts and how they can be dealt with, links to previous posts below:
Oversize framing and Spliced mounts and Long mount
The blue mount in these photos is on a movie poster I framed recently, the mount has been made by joining two sheets of mountboard together, to give a mount larger than the standard size of 32" x 44" that this colour is available in. The top photo shows the join is unnoticeable when viewed face on, only really from the side or above can the join be seen, and even then only from a few inches away. I have another of these types of oversize mounts to do next week.
