As previously stated, there were two distinctly different adhesives which led to two different methods of removing the board. Fortunately for those that were matted, the mat boards were cut larger than the backing board and taped together on the back. Because there was not adhesive between the sample and the mat, I was able to simply remove the tape on the back and thus remove the mat. I found a surprise in one of these worth photographing.
Because the spray mount adhesive was not water soluble, I had to remove the backing board dry. I did this using a shaped bone folder. I removed the board slowly, in layers. Luckily these boards split easily. I continued removing layers until I was as close as I could comfortably get to the paper. Some areas lifted clean away from the paper without fuss. For the areas where the board was well and truly stuck, I used the bone folder to gently scrape and the surface and thin the board down to the last layer before the paper, and left it. Forced removal would skin the paper. The following picture shows this process about halfway through, and the tool used.
I did have some minor issues on the first couple samples with skinning the paper. After I began to get the hang of it, I realized this was because I was trying to take off too much backing board at once. I also found that when I was down to the last few layers, the thinner I could get the board, the easier it came away from the paper.
In the next parts I will discuss my wet board removal method, and how I treated the missing pieces on damaged samples.