For gallery shows, I use Light Impressions's Westminster buffered mat board. I cut a mat using the add about 3/8" to both sides and top. For the bottom I add an extra 1/2" to that side and then cut the mat. With the dry mount tissue attached to the print I run the print thru the paper trimmer and cut the print to size using the image as the guide mark. I then place the print on the board and put the cut mat on the whole thing and square up the mat. Then I square up the print and then tack a corner down to the back board. Once that happens I place the print and the back board in a pre-heated drymount press. The backboard and the tacked down print are slid in between two (2) pieces of mounting board that are at least as large as the backing board. The press is closed and I count "one thousand one one thousand...for about a minute. The press is opened and I remove the print and board. I generally flex the board and inspect the bond. Sometimes it needs to go back into the press for an additional minute. After the print is mounted and looks like it won't come off, I generally place the bonded material "upside down" to cool. If I have done the job correctly when the print is cooled I then place the mat on the board. I generally use 4 ply mat board and I think that is enough to separate the print surface from the glass if it is to be framed.