After trialling the use of the adhesive as a sealing agent for the two layers, I thought that perhaps, with enough heat, I could bind together the seams without any glue, in a cleaner manner. This worked brilliantly when I used the iron around the edges of a sample. The trick is not overheating, because then the PVC melts. I then attempted to join two sections together, as I would be doing in the seams. This worked well also!